Lungs and breathing
Everything in the library studied for it, medical and holistic together. Within each kind, what was shown to help comes first, strongest evidence first. What was tested and not shown to help stays on the list.
Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on
Medication
Lung function and symptoms in asthma
Shown to improve lung function, morning peak flow and symptoms against placebo in mild to moderate asthma, and to cut withdrawals for asthma attacks on budesonide by about 83%.
The numbers and sources
- Effect
- Fluticasone at 100 to 1,000 mcg a day raised FEV1 by 0.1 to 0.43 L and morning peak flow by 23 to 46 L/min, improved symptom scores and cut rescue inhaler use by 1 to 1.4 puffs a day. At 1,000 to 1,500 mcg a day, more people could stop oral prednisolone (Peto OR 14.07) [1]. Budesonide raised FEV1 by 3.7% of predicted and morning peak flow by 29 L/min, and withdrawal for asthma exacerbation was less likely (RR 0.17, 95% CI 0.09 to 0.33) [2].
- Population
- 86 studies with 16,160 participants [1]; 43 studies with 2,801 participants [2].
- Sources
- [1], [2]
- Caveats
- Low doses of fluticasone gave only slightly smaller gains than high doses [1]. Budesonide doses of 500 to 800 mcg a day showed slightly larger effects than lower doses, with no added gain at high doses [2].
Triple inhalers in COPD
Shown to cut moderate or severe COPD exacerbations against dual inhalers, and to lower deaths against two bronchodilators without a steroid, but not against a steroid-bronchodilator pair.
Compared with a long-acting antimuscarinic alone, a long-acting antimuscarinic with a long-acting beta-agonist, or an inhaled steroid with a long-acting beta-agonist [11][12][13]
The numbers and sources
- Effect
- Triple therapy lowered moderate or severe exacerbations against an antimuscarinic alone (rate ratio 0.71), two bronchodilators (0.78) and a steroid-beta-agonist pair (0.77). Pneumonia was higher than with two bronchodilators (RR 1.53) [11]. Over 52 weeks, deaths were lower than with two bronchodilators (RR 0.69, 95% CI 0.53 to 0.90) but not than with a steroid-beta-agonist pair (RR 0.94, 95% CI 0.72 to 1.24) [12]. A 2025 analysis also found fewer deaths than with two bronchodilators (RR 0.76, 95% CI 0.60 to 0.97) [13].
- Population
- 21 trials [11]; 6 trials with 22,669 patients [12]; randomized trials in moderate to severe COPD [13].
- Sources
- [11], [12], [13]
- Caveats
- Most trials enrolled people with advanced COPD and recent exacerbations [11]. The three analyses share many trials.
Asthma attacks
Shown to lower hospital admission and relapse after an asthma attack, with about 8 to 10 people treated to prevent one.
The numbers and sources
- Effect
- Given within an hour of arriving at an emergency department, systemic corticosteroids lowered hospital admission (OR 0.40, 95% CI 0.21 to 0.78), a number needed to treat of 8. Oral corticosteroids in children showed a larger effect (OR 0.24, 95% CI 0.11 to 0.53), and no adult trial used the oral route [1]. After discharge, a short course lowered relapse needing more care in the first week (RR 0.38, 95% CI 0.2 to 0.74) and over 21 days (RR 0.47, 95% CI 0.25 to 0.89), and lowered later hospitalization (RR 0.35, 95% CI 0.13 to 0.95), with about 10 treated to prevent one relapse [2].
- Population
- 863 people with acute asthma in 12 studies [1]; 374 people in 6 trials, 5 of them of oral corticosteroids [2].
- Sources
- [1], [2]
- Caveats
- The reviews date from 2001 and 2007 and cover small trials. Side effects were rarely reported and did not differ from placebo over 7 to 10 days [2].
Quick relief of airway narrowing in asthma
Shown to improve lung function more than a placebo inhaler in people with asthma, starting within about 5 minutes and lasting about 4 hours in responders.
Compared with a placebo inhaler [1]
The numbers and sources
- Effect
- In two 12-week trials, 2 inhalations of albuterol produced greater improvement in FEV1 from before the dose than placebo. In people whose FEV1 rose at least 15% within 30 minutes, the mean time to that rise was 5.4 minutes, peak effect came at 56 minutes, and the effect lasted about 4 hours, up to 6 hours in some [1].
- Population
- 610 people aged 12 and older with mild to moderate asthma in two randomized double-blind trials [1].
- Sources
- [1]
- Caveats
- Label trials. Some participants also used inhaled steroids [1].
Preventing exercise-induced airway narrowing
Shown to protect against the drop in lung function after exercise, with about 18 percentage points less fall in FEV1 than placebo after a single dose.
The numbers and sources
- Effect
- A single dose of a short- or long-acting beta-agonist before exercise reduced the maximum fall in FEV1 against placebo (MD -17.67%, 95% CI -19.51% to -15.84%). Side effects did not differ from placebo [2]. In a label trial, 2 inhalations of albuterol about 30 minutes before exercise prevented exercise-induced bronchospasm more than placebo [1].
- Population
- 53 trials with 1,139 participants, 45 of single doses [2]; 24 adults with asthma [1].
- Sources
- [2], [1]
- Caveats
- The meta-analysis pooled short- and long-acting beta-agonists, and heterogeneity was high in children [2].
Stable COPD
Shown to improve lung function slightly and daily breathlessness in stable COPD compared with placebo, and people preferred it to placebo about 9 times as often.
Compared with placebo [3]
The numbers and sources
- Effect
- Regular short-acting beta-agonists raised FEV1 by 0.14 L (95% CI 0.04 to 0.25) and FVC by 0.30 L, raised morning peak flow by 29 L/min, and improved daily breathlessness (SMD 1.33). Dropping out for treatment failure was about half as likely (RR 0.49, 95% CI 0.33 to 0.73) [3].
- Population
- 13 crossover trials in people with stable COPD [3].
- Sources
- [3]
- Caveats
- Crossover trials of at least a week. The review predates the long-acting bronchodilators now used for COPD [3].
Continuous nebulized doses in a severe attack
Shown to cut hospital admission when beta-agonists were nebulized continuously rather than in separate doses in the emergency department, most in people with severe airway obstruction.
Compared with intermittent nebulized beta-agonist [5]
The numbers and sources
- Effect
- Continuous treatment lowered admission against intermittent treatment (RR 0.68, 95% CI 0.5 to 0.9), and more in severe obstruction (RR 0.64). FEV1 (SMD 0.3) and peak flow (SMD 0.33) improved slightly more by 2 to 3 hours. Pulse rate and blood pressure did not differ [5].
- Population
- 461 patients with acute asthma in 8 trials [5].
- Sources
- [5]
- Caveats
- Small trials. The review covers beta-agonists given in emergency care [5].
Preventing COPD flare-ups with long-term azithromycin
Shown to cut COPD flare-ups with long-term macrolides such as azithromycin, from 61% to 47% of people, 8 treated for one fewer, with hearing loss reported on azithromycin.
Compared with placebo [14]
The numbers and sources
- Effect
- People with one or more exacerbations fell from 61% to 47% (OR 0.57, 95% CI 0.42 to 0.78), a number needed to treat of 8 over 3 to 12 months, and yearly exacerbations fell (rate ratio 0.67). Quality of life improved by less than the clinically important margin (MD -1.94 on the St George's questionnaire). Hospital admissions, lung function, serious adverse events and deaths did not differ. Azithromycin was linked to hearing loss, often reversible [14].
- Population
- 3,932 people in 14 trials, mean age 65 to 72, mostly moderate to severe COPD with frequent flare-ups [14].
- Sources
- [14]
- Caveats
- The benefit applies to macrolides taken at least three times a week. Resistance rose in some studies [14].
Adding a long-acting bronchodilator (combination inhalers) in asthma
Shown to cut asthma exacerbations needing oral steroids from 15% to 11% when a long-acting beta-agonist was added to an inhaled steroid in adults.
Compared with the same dose of inhaled steroid alone [4][5]
The numbers and sources
- Effect
- Adding a long-acting beta-agonist cut exacerbations needing oral steroids from 15% to 11% (RR 0.77, 95% CI 0.68 to 0.87), cut rescue use by 0.58 puffs a day and halved withdrawals for poor control (RR 0.50). In children the estimate was not significant (RR 0.89, 95% CI 0.58 to 1.39) [4]. In four 26-week safety trials, at least one asthma exacerbation occurred in 9.8% on a combination inhaler and 11.7% on an inhaled steroid alone (RR 0.83, 95% CI 0.78 to 0.89) [5].
- Population
- 21,248 participants, 4,625 of them children, in 77 trials [4]; 36,010 people aged 12 and older [5].
- Sources
- [4], [5]
- Caveats
- Higher than usual doses of the long-acting beta-agonist gave less benefit [4].
As-needed budesonide-formoterol in mild asthma
Shown to cut exacerbations needing oral steroids by about half against a reliever alone in mild asthma, and to match regular inhaled steroids with less steroid taken.
Compared with an as-needed fast-acting bronchodilator alone [6]; as-needed albuterol [7]; regular inhaled steroid with an as-needed reliever [6][7]
The numbers and sources
- Effect
- Against a fast-acting reliever alone, exacerbations needing oral steroids fell from 109 to 52 per 1,000 (OR 0.45, 95% CI 0.34 to 0.60). Against regular inhaled steroids, they were 65 and 81 per 1,000 (OR 0.79, 95% CI 0.59 to 1.07), with 154 μg a day less inhaled steroid [6]. In one 52-week trial, the annual exacerbation rate was 0.195 on budesonide-formoterol as needed and 0.400 on albuterol as needed (relative rate 0.49), and did not differ from regular budesonide (relative rate 1.12, 95% CI 0.70 to 1.79) [7].
- Population
- 9,657 participants aged 12 and older in 6 trials, mean age 36 to 43 [6]; 668 adults with mild asthma [7].
- Sources
- [6], [7]
- Caveats
- All trials used budesonide 200 μg with formoterol 6 μg in a dry powder inhaler [6]. One trial was open-label and part funded by AstraZeneca [7].
One combination inhaler for both daily control and relief (SMART)
Shown to cut asthma exacerbations by about a third against fixed-dose combination controllers, 6.4 fewer per 100 people aged 12 and older.
Compared with the same or higher dose of inhaled steroid and long-acting beta-agonist as controller, or inhaled steroid alone [8]
The numbers and sources
- Effect
- In people aged 12 and older, using one budesonide-formoterol inhaler for both control and relief lowered exacerbation risk against the same controller dose (RR 0.68, 95% CI 0.58 to 0.80, risk difference -6.4%) and a higher controller dose (RR 0.77, risk difference -2.8%). In children aged 4 to 11, risk fell against a higher steroid dose (RR 0.55) and against the same combination dose (RR 0.38) [8].
- Population
- 22,748 patients in 16 randomized trials, 341 of them aged 4 to 11 [8].
- Sources
- [8]
- Caveats
- 15 of the 16 trials tested budesonide-formoterol. The children's results rest on few patients [8].
Flare-ups in COPD, inhaled steroid alone
Shown to reduce COPD exacerbations by about 0.2 to 0.3 a year and slow the decline in quality of life, with no effect on deaths.
Compared with placebo [9]
The numbers and sources
- Effect
- Long-term inhaled steroids lowered the exacerbation rate (MD -0.26 per person per year, 95% CI -0.37 to -0.14) and slowed the decline in quality of life (MD -1.22 units a year). They did not consistently slow FEV1 decline (MD 5.80 mL a year, 95% CI -0.28 to 11.88) and did not change mortality (OR 0.98, 95% CI 0.83 to 1.16) [9].
- Population
- 16,154 participants with COPD in 55 trials [9].
- Sources
- [9]
- Caveats
- One large trial found a significant slowing of FEV1 decline, but the pooled results were inconsistent [9].
Combination inhaler against a long-acting bronchodilator alone in COPD
Shown to lower COPD exacerbations to about 0.76 a year per 1 a year on a long-acting beta-agonist alone, with no difference in deaths and more pneumonia.
Compared with the same long-acting beta-agonist alone [10]
The numbers and sources
- Effect
- Combination inhalers lowered the exacerbation rate (rate ratio 0.76, 95% CI 0.68 to 0.84). Mortality did not differ (OR 0.92). Pneumonia was more common (OR 1.55) [10].
- Population
- 11,794 people with severe COPD in 14 trials, 10 of fluticasone-salmeterol and 4 of budesonide-formoterol [10].
- Sources
- [10]
- Caveats
- Low-quality evidence for exacerbations, with high withdrawal rates and heterogeneity (I² 68%) [10].
Asthma, against placebo
Shown to improve lung function, daytime symptoms and night waking against placebo in mild to moderate asthma, with FEV1 up 0.22 L more than placebo in one trial.
Compared with placebo [1]
The numbers and sources
- Effect
- Over 12 weeks, FEV1 rose 13.0% on montelukast 10 mg and 4.2% on placebo, a difference of 0.22 L (95% CI 0.17 to 0.27). In the second trial, daytime symptom scores fell 0.49 against 0.26, rescue inhaler use fell 1.65 against 0.42 puffs a day, and night waking fell 2.03 against 0.78 times a week [1].
- Population
- 1,576 adults and adolescents aged 15 and older with mild or moderate asthma in two 12-week trials, 795 on montelukast and 530 on placebo [1].
- Sources
- [1]
- Caveats
- Label trials. Doses above 10 mg a day gave no added benefit [1].
Asthma, added to an inhaled steroid
Shown to halve exacerbations needing oral steroids when added to an inhaled steroid in adults and adolescents, about 22 treated for one fewer exacerbation.
Compared with the same dose of inhaled steroid alone [3]
The numbers and sources
- Effect
- Adding an anti-leukotriene to the same inhaled steroid dose halved the number of people with exacerbations needing oral steroids (RR 0.50, 95% CI 0.29 to 0.86), a number needed to treat of 22 over 6 to 16 weeks. All adverse events did not differ (RR 1.06) [3].
- Population
- 6,128 adults and adolescents in 37 studies, 24 of montelukast; 815 people in the 4 studies of the main outcome [3].
- Sources
- [3]
- Caveats
- Moderate-quality evidence from few studies for the main outcome. Zafirlukast and pranlukast trials are included [3].
Exercise-induced airway narrowing
Shown to reduce the drop in lung function after exercise when taken 2 hours before, a 13% fall against 22% on placebo, with less protection at 24 hours.
Compared with placebo [1]
The numbers and sources
- Effect
- In one crossover trial, the mean maximum fall in FEV1 after exercise 2 hours after a 10 mg dose was 13% on montelukast and 22% on placebo (difference -9%, 95% CI -12 to -5). At 24 hours the falls were 10% and 14%. Some patients were protected at 8.5 and 24 hours and some were not [1].
- Population
- 160 people aged 15 and older with exercise-induced bronchoconstriction in three crossover trials, 47 in the trial reported [1].
- Sources
- [1]
- Caveats
- Label trials with single doses. The label reports the other two trials as similar [1].
COPD flare-ups
Shown to cut treatment failure in COPD flare-ups by about half, with 9 treated to prevent one, and no change in deaths.
The numbers and sources
- Effect
- Systemic corticosteroids lowered treatment failure against placebo (OR 0.48, 95% CI 0.35 to 0.67), a number needed to treat of 9 (95% CI 7 to 14), and lowered relapse by 1 month (HR 0.78, 95% CI 0.63 to 0.97). Hospital stay was 1.22 days shorter. Deaths within 30 days did not differ (OR 1.00, 95% CI 0.60 to 1.66). Adverse events were more frequent (OR 2.33, 95% CI 1.59 to 3.43), one extra for every 6 treated, and high blood sugar was more frequent (OR 2.79, 95% CI 1.86 to 4.19). Oral and injected treatment did not differ in treatment failure, relapse or deaths [3].
- Population
- 1,787 people in 16 studies, mean age 68, with a median treatment length of 14 days [3].
- Sources
- [3]
- Caveats
- Lung function was better at 72 hours and not at later time points [3].
Croup in children
Shown to lower croup symptom scores in children within 2 to 12 hours against placebo, with fewer return visits on dexamethasone than on prednisolone.
The numbers and sources
- Effect
- Against placebo, glucocorticoids lowered croup scores at 2 hours (SMD -0.65, 95% CI -1.13 to -0.18), 6 hours (SMD -0.76, 95% CI -1.12 to -0.40) and 12 hours (SMD -1.03, 95% CI -1.53 to -0.53). Prednisolone and dexamethasone did not differ in croup score at 2 hours. Return visits or admissions were about half as frequent on dexamethasone (RR 0.55, 95% CI 0.28 to 1.11), and fewer children on dexamethasone needed additional glucocorticoid (RR 0.72, 95% CI 0.53 to 0.97) [12].
- Population
- 5,888 children with croup in 45 trials [12].
- Sources
- [12]
- Caveats
- The reviewers rated the evidence against placebo low certainty and judged 98% of studies at high or unclear risk of bias. The interval for return visits includes no difference [12].
Severe COVID-19 and pneumonia in hospital
Shown to lower 28-day deaths in hospitalized COVID-19 patients, 22.9% against 25.7%, with the benefit limited to those on oxygen or a ventilator.
The numbers and sources
- Effect
- Dexamethasone 6 mg a day for up to 10 days, by mouth or vein, lowered 28-day deaths from 25.7% on usual care to 22.9% (rate ratio 0.83, 95% CI 0.75 to 0.93). Deaths were 29.3% against 41.4% in those on a ventilator and 23.3% against 26.2% in those on oxygen. In those on no respiratory support they were 17.8% against 14.0% (rate ratio 1.19, 95% CI 0.92 to 1.55) [13]. In severe community-acquired pneumonia, added corticosteroids lowered deaths (RR 0.47, 95% CI 0.3 to 0.74) and C-reactive protein on day 8 (SMD -0.8, 95% CI -1.11 to -0.5), with no difference in gastrointestinal bleeding or high blood sugar [14].
- Population
- 6,425 people hospitalized with COVID-19, 2,104 on dexamethasone and 4,321 on usual care [13]; 665 people with severe community-acquired pneumonia in 10 trials [14].
- Sources
- [13], [14]
- Caveats
- The COVID-19 trial was open label [13]. The pneumonia trials were small and used several corticosteroids and dosing schedules, so they do not test oral treatment alone [14].
Severe asthma attacks in recent-onset mild asthma
One large trial found low-dose budesonide cut the risk of a severe asthma exacerbation by 44% over 3 years in mild persistent asthma of recent onset.
Compared with placebo [3]
The numbers and sources
- Effect
- At least one severe asthma exacerbation occurred in 117 of 3,597 people on budesonide and 198 of 3,568 on placebo (HR 0.56, 95% CI 0.45 to 0.71) [3].
- Population
- 7,241 people in 32 countries who had had mild persistent asthma for under 2 years and no regular steroid treatment [3].
- Sources
- [3]
- Caveats
- Children under 11 grew 1.34 cm less over 3 years (see Risks) [3].
- Why limited
- This rests on one trial, of 7,241 people. Strength counts independent studies that agree, so one trial is limited at any size.
Walking distance in pulmonary arterial hypertension
One trial found walking distance rose about 45 to 50 m more than placebo over 12 weeks in people with pulmonary arterial hypertension.
The numbers and sources
- Effect
- After 12 weeks, six-minute walk distance rose by 45 m, 46 m and 50 m more than placebo on 20, 40 and 80 mg three times daily. Mean pulmonary artery pressure fell and functional class improved. Clinical worsening did not differ from placebo [6].
- Population
- 278 patients with symptomatic pulmonary arterial hypertension [6].
- Sources
- [6]
- Caveats
- One trial, not powered for mortality. It describes people with the disease, not healthy athletes.
Furosemide before a blood transfusion
Limited evidence: four small trials of furosemide before transfusion measured only breathing and pressure markers, and a Cochrane review found too little evidence to judge clinical benefit.
Compared with no diuretic or placebo before transfusion [13]
The numbers and sources
- Effect
- One study found better inspired oxygen fraction and two found better pulmonary capillary wedge pressure with furosemide. None measured clinically important outcomes such as transfusion-related fluid overload [13].
- Population
- 100 people in 4 trials [13].
- Sources
- [13]
- Caveats
- Too small and too narrow to show clinical benefit or harm [13].
Spacer or nebulizer in an asthma attack
Not shown to change hospital admission whether a beta-agonist was given by spacer or by nebulizer. Children spent 33 minutes less in the emergency department with a spacer.
Compared with the same drug given by nebulizer [4]
The numbers and sources
- Effect
- Admission did not differ between spacer and nebulizer in adults (RR 0.94, 95% CI 0.61 to 1.43) or children (RR 0.71, 95% CI 0.47 to 1.08). In children, time in the emergency department was 33 minutes shorter with a spacer, pulse rose less and tremor was less likely (RR 0.64). Lung function was similar [4].
- Population
- 1,897 children and 729 adults with acute asthma in 39 trials [4].
- Sources
- [4]
- Caveats
- Moderate-quality evidence. The trials compared delivery methods, not the drug against placebo [4].
Regular scheduled use against use as needed
Not shown to change lung function or major asthma exacerbations when taken on a schedule rather than as needed, though regular users needed slightly less rescue medicine.
Compared with the same drug used as needed [6]
The numbers and sources
- Effect
- No clinically or statistically significant differences were found in airway caliber. Regular treatment groups used 0.80 fewer rescue puffs a day and had 6.7% fewer days with symptoms. The odds of at least one major exacerbation did not differ [6].
- Population
- 49 trials of short-acting beta-agonists in chronic asthma [6].
- Sources
- [6]
- Caveats
- The review dates from 2003, and many trials were crossover studies [6].
As-needed albuterol alone against as-needed budesonide-formoterol
Shown to leave about twice the asthma exacerbation rate of as-needed budesonide-formoterol in adults with mild asthma, 0.400 a year against 0.195.
Compared with as-needed budesonide-formoterol [7][8]; regular budesonide plus as-needed albuterol [7]
The numbers and sources
- Effect
- Over 52 weeks, the annual exacerbation rate was 0.400 on albuterol as needed and 0.195 on budesonide-formoterol as needed (relative rate 0.49, 95% CI 0.33 to 0.72). Severe exacerbations numbered 23 and 9 (RR 0.40, 95% CI 0.18 to 0.86) [7]. Across trials of a fast-acting bronchodilator alone, 109 per 1,000 had an exacerbation needing oral steroids against 52 per 1,000 on budesonide-formoterol as needed (OR 0.45, 95% CI 0.34 to 0.60) [8].
- Population
- 668 adults with mild asthma in an open-label trial [7]; 9,657 participants in 6 trials, mean age 36 to 43 [8].
- Sources
- [7], [8]
- Caveats
- The trial was open-label and funded in part by AstraZeneca [7]. In the pooled analysis the fast-acting comparators were terbutaline and formoterol, not albuterol [8].
Acute bronchitis and chest infections
Not shown to improve overall recovery from acute bronchitis, with cough about half a day shorter, and amoxicillin did not shorten bad symptoms in a 2,061-person trial.
The numbers and sources
- Effect
- The share clinically improved did not differ (RR 1.07, 95% CI 0.99 to 1.15). Cough was less frequent at follow-up (RR 0.64, a number needed to treat of 6) and lasted 0.46 days less. Adverse effects were more frequent (RR 1.20), one extra for every 24 treated [4]. In adults with a chest infection not suspected to be pneumonia, amoxicillin 1 g three times daily did not shorten moderately bad symptoms (HR 1.06, 95% CI 0.96 to 1.18). New or worse symptoms were 15.9% against 19.3% (number needed to treat 30), and nausea, rash or diarrhea one extra per 21 treated, including in people 60 or older [5].
- Population
- 5,099 people in 17 trials [4]; 2,061 adults in 12 European countries [5].
- Sources
- [4], [5]
- Caveats
- Frail older people with several conditions may have been left out of trials [4].
Asthma, montelukast alone against an inhaled steroid
Shown to leave more asthma exacerbations needing oral steroids than an inhaled steroid, one extra exacerbation for every 28 people treated with montelukast instead.
Compared with inhaled corticosteroids [2]
The numbers and sources
- Effect
- People treated with an anti-leukotriene instead of an inhaled steroid were more likely to have an exacerbation needing oral steroids (RR 1.51, 95% CI 1.17 to 1.96), one more for every 28 treated (95% CI 15 to 82). The gap was larger with moderate airway obstruction (RR 2.03) than mild (RR 1.25) [2].
- Population
- 10,005 adults and 3,333 children with mild or moderate persistent asthma in 56 trials of 4 to 52 weeks [2].
- Sources
- [2]
- Caveats
- The inhaled steroid dose was about 200 µg a day of beclomethasone or equivalent. The review covers anti-leukotrienes as a group [2].
Added to an inhaled steroid, against an added long-acting beta-agonist
Shown to leave slightly more exacerbations than adding a long-acting beta-agonist to an inhaled steroid, 13% against 11%.
Compared with a long-acting beta-agonist added to the inhaled steroid [4]
The numbers and sources
- Effect
- Exacerbations needing oral steroids were 13% with an anti-leukotriene plus inhaled steroid and 11% with a long-acting beta-agonist plus inhaled steroid (RR 0.87, 95% CI 0.76 to 0.99 favoring the beta-agonist), one fewer for every 62 treated. Lung function, symptoms and rescue use also favored the beta-agonist [4].
- Population
- 7,208 participants in 18 trials, 336 of them children aged 6 to 17 [4].
- Sources
- [4]
- Caveats
- High-quality evidence. The choice of anti-leukotriene did not change the result [4].
Chronic cough
Not shown to resolve long-lasting cough in adults more than placebo overall. In infants, more side effects occurred on a proton pump inhibitor.
Compared with placebo [16]
The numbers and sources
- Effect
- In adults, pooled data showed no significant difference in total cough resolution (OR 0.46, 95% CI 0.19 to 1.15). Cough scores improved only in sensitivity analyses (SMD -0.41). In one infant trial, cough did not improve and adverse events rose (OR 5.56, 95% CI 1.18 to 26.25), one extra event for every 11 infants treated for 4 weeks [16].
- Population
- 19 studies, 13 in adults, of which 9 compared 2 to 3 months of a proton pump inhibitor with placebo [16].
- Sources
- [16]
- Caveats
- Trials differed in how they measured cough. Children's studies could not be combined [16].
Asthma in people with reflux
Not shown to consistently improve lung function, asthma symptoms or asthma medicine use in people with asthma and reflux.
Compared with control groups the abstract does not describe [17]
The numbers and sources
- Effect
- Anti-reflux treatment did not consistently improve lung function, asthma symptoms, night-time asthma or use of asthma medicines. The authors suggested some subgroups may benefit but could not predict which [17].
- Population
- 12 trials, 6 of proton pump inhibitors, lasting 1 week to 6 months, in adults and children with asthma and reflux [17].
- Sources
- [17]
- Caveats
- The review pooled proton pump inhibitors with H2 blockers, surgery and lifestyle measures, and dates from 2003 [17].
Supplements
Chronic bronchitis and COPD exacerbations
Shown to lower exacerbations in chronic bronchitis and COPD, about 13 to 25% fewer. The reviews disagree on which dose range showed it.
The numbers and sources
- Effect
- Across 13 studies (4,155 patients), NAC lowered exacerbations (RR 0.75, 95% CI 0.66 to 0.84). In spirometry-confirmed COPD, doses above 600 mg a day gave RR 0.75 (95% CI 0.68 to 0.82) [3]. A 2026 meta-analysis of 14 RCTs (2,856 COPD patients) found fewer exacerbations (RR 0.87, 95% CI 0.79 to 0.96). There, 600 mg a day or less gave RR 0.84 (95% CI 0.73 to 0.97) and higher doses RR 0.88 (95% CI 0.73 to 1.06). FEV1, FVC, St. George's Respiratory Questionnaire scores and glutathione did not improve [4]. A 2026 dose meta-analysis found FEV1, FVC and FEV1/FVC improved at 1,200 mg a day or more and not at lower doses [5].
- Population
- 1,933 on NAC and 2,222 on placebo or control [3]; 1,295 on NAC and 1,314 controls in the exacerbation analysis of [4]; COPD trials from 2000 to 2024 [5].
- Sources
- [3], [4], [5]
- Caveats
- The effect was more apparent in patients without airway obstruction [3]. The two exacerbation reviews disagree on which dose range showed the effect [3][4]. The lung function reviews disagree, and [5] reported substantial heterogeneity for some outcomes.
Asthma control
Limited evidence: 4 trials found better asthma control scores and lung function in people with asthma. Peak flow did not change.
The numbers and sources
- Effect
- In 4 RCTs, Nigella sativa raised asthma control test scores (SMD 0.50, 95% CI 0.11 to 0.88) and FEV1 (SMD 1.84, 95% CI 0.07 to 3.60). Peak flow, IL-4 and interferon gamma did not change significantly [8].
- Population
- People with asthma in 4 RCTs [8].
- Sources
- [8]
- Caveats
- Four trials, with a wide interval for FEV1.
Lung health, cough and asthma
Not studied in people. The EU medicines agency lists mullein flower tea as a traditional herbal medicine for sore throat with dry cough and cold, based on long-standing use.
No study in people. This rests on documented traditional use.
The numbers and sources
- Effect
- The European Union herbal monograph adopted by the European Medicines Agency's herbal committee in 2018 lists mullein flower, as a tea taken by mouth, as a traditional herbal medicinal product used to relieve symptoms of sore throat associated with dry cough and cold. It states the indication rests exclusively on long-standing use, and gives no well-established use indication [3].
- Population
- Traditional use in Europe, as reviewed by the European Medicines Agency [3].
- Sources
- [3]
- Caveats
- Traditional use is a record of how long people have used it, not a test of its effect. The monograph covers sore throat with dry cough and cold only, not asthma, bronchitis or lung health. No controlled trial in people was located.
Therapies
Breathlessness and physical function in advanced breast cancer
One trial of 385 women found less breathlessness with reflexology than with lay foot manipulation or conventional care, and better physical functioning than conventional care.
Compared with lay foot manipulation [6]; conventional care [6]
The numbers and sources
- Effect
- Shortness of breath was less severe with reflexology than with conventional care (P < 0.01) and lay foot manipulation (P = 0.02). Physical functioning improved more than with conventional care (P = 0.04). Breast cancer quality of life, depression, anxiety, pain and nausea did not differ [6].
- Population
- 385 women with advanced breast cancer receiving chemotherapy or hormone therapy [6].
- Sources
- [6]
- Caveats
- One trial with several outcomes, most of which did not differ.
Asthma, high blood pressure and period pain
Not shown to treat asthma in children, high blood pressure or period pain. Every high- or acceptable-quality trial found manipulation no better than sham.
Compared with sham interventions [10]
The numbers and sources
- Effect
- All randomized trials of acceptable or high quality found spinal manipulation was not superior to sham for infantile colic, childhood asthma, hypertension, primary dysmenorrhea and migraine. No trial tested whether manipulation prevents any of these conditions [10].
- Population
- 6 randomized trials with 534 participants [10].
- Sources
- [10]
- Caveats
- Few trials for each condition. Six of the 50 researchers at the review summit did not approve the final report [10].
COVID-19
Limited evidence: pooled trials found ozone did not shorten hospital stays or reduce intensive care admissions or deaths from COVID-19, though fewer PCR tests stayed positive.
Compared with placebo, sham, saline or standard care [12]
The numbers and sources
- Effect
- In meta-analyses of randomized trials, ozone therapy lowered PCR positivity at follow-up (RR 0.07, 95% CI 0.01 to 0.34), which the reviewers judged a clinically unimportant surrogate. Hospital stay, intensive care admission and mortality did not differ [12].
- Population
- Meta-analyses of trials in patients with COVID-19, within an umbrella review of 7 meta-analyses [12].
- Sources
- [12]
- Caveats
- Certainty was low or very low for every outcome in the umbrella review, and safety outcomes were reported inconsistently [12].
Practices
Asthma, against no breathing training
Shown in a Cochrane review to improve asthma quality of life slightly at 3 months against inactive controls. Asthma symptom scores and FEV1 in liters did not clearly change.
Compared with inactive control groups [15]
The numbers and sources
- Effect
- Asthma quality of life improved at 3 months (MD 0.42 points, 95% CI 0.17 to 0.68, 4 studies, 974 participants, moderate certainty). Hyperventilation symptoms fell at 4 to 6 months (MD -3.22) but not at 6 months. Asthma Control Questionnaire scores were inconclusive (MD -0.08 over 6 months, 95% CI -0.22 to 0.07). FEV1 in liters was inconclusive (MD -0.10 L, very low certainty), while FEV1 % of predicted improved by 6.88% [15].
- Population
- 2,880 adult outpatients with mild to moderate asthma in 22 trials, 14 of them of yoga breathing [15].
- Sources
- [15]
- Caveats
- Trials differed in technique, sessions and outcomes, and most reported their methods incompletely. Adverse effects were not assessed [15].
Pneumonia and respiratory disease
Linked to fewer hospital diagnoses of pneumonia and other respiratory disease in Finnish men who used a sauna 2 or more times a week.
The numbers and sources
- Effect
- Over 25.6 years, 379 of 1,935 men had a hospital diagnosis of chronic obstructive pulmonary disease, asthma or pneumonia. Against one session a week or fewer, hazard ratios were 0.73 (95% CI 0.58 to 0.92) at 2 to 3 sessions and 0.59 (95% CI 0.37 to 0.94) at 4 or more [17]. For pneumonia alone, in 2,210 men with 375 cases, the fully adjusted hazard ratios were 0.72 (95% CI 0.57 to 0.90) and 0.63 (95% CI 0.39 to 1.00) [18].
- Population
- Finnish men aged 42 to 61 [17][18].
- Sources
- [17], [18]
- Caveats
- Observational, and both analyses use the same cohort. Only men were studied.
Asthma, against asthma education
One trial of 183 adults found physiotherapist breathing training improved asthma quality of life and anxiety more than nurse asthma education at 6 months, not at 1 month.
Compared with nurse-delivered asthma education, to control for clinician attention [16]
The numbers and sources
- Effect
- At 6 months, breathing training improved asthma quality of life by 0.38 units more than education (95% CI 0.08 to 0.68), with differences in anxiety (1.1 points), depression (0.8) and hyperventilation scores (3.2). No differences were seen at 1 month. Airway physiology, inflammation and hyper-responsiveness did not change [16]. The Cochrane review pooled this comparison from the same single trial [15].
- Population
- 183 adults with asthma and impaired health status in UK primary care [16].
- Sources
- [16], [15]
- Caveats
- Three sessions, one trial, single-blind [16].
Asthma control
One crossover trial of 51 adults with asthma found 4 weeks of nightly mouth taping did not change peak flow, symptoms or any secondary measure.
Compared with usual breathing at night [7]
The numbers and sources
- Effect
- Participants taped for a median 26 of 28 nights. Morning peak expiratory flow differed by -1 L/min (95% CI -9 to 7) and symptom scores by -0.12 (95% CI -0.30 to 0.06), and no secondary measure differed [7].
- Population
- 51 adults with symptomatic asthma, mean FEV1 86% of predicted [7].
- Sources
- [7]
- Caveats
- Single-blind assessment, since participants knew when they taped [7].
Daily life
Lung cancer after quitting
Linked to steadily lower lung cancer risk with each year after quitting in pooled cohorts, with about a fifth of the excess remaining 20 years on.
Compared with current smokers, as each review defined its reference [11][12]; people who continued to smoke, and never smokers [13]; never-smokers [3]; continuing smokers, by age at stopping [14]
The numbers and sources
- Effect
- The share of the reducible excess risk remaining was 81.4% 1 year after quitting, 57.2% at 5 years, 36.9% at 10, 26.7% at 15 and 19.7% at 20 [11]. Lung cancer death had an RR of 0.64 (95% CI 0.55 to 0.76) in people who had quit for under 10 years, 0.33 for 10 to 20 years and 0.16 for over 20 years, against 0.11 in never smokers [12]. Heavy former smokers had 39.1% lower lung cancer risk than continuing smokers within 5 years, yet a hazard ratio of 3.85 (95% CI 1.80 to 8.26) against never smokers after 25 years [13]. Women who stopped at 25 to 34 had a lung cancer death rate 1.84 times that of never-smokers [3]. For UK men who stopped at 60, 50, 40 or 30, the risk of dying of lung cancer by 75 was 10%, 6%, 3% and 2%, against 16% in continuing smokers [14].
- Population
- 49 prospective cohorts in 20 countries [11]. 969,560 people in 24 studies [12]. 8,907 Framingham participants with 284 lung cancers over a median 28.7 years [13]. 1.2 million UK women [3]. 982 lung cancer cases and 3,185 controls in 1990, with UK national rates [14].
- Sources
- [11], [12], [13], [3], [14]
- Caveats
- Observational. People who quit after symptoms begin can make early quitters look worse, which is reverse causation. In heavy smokers, 4 in 10 lung cancers occurred more than 15 years after quitting [13].
Lung function and COPD after quitting
Shown to slow the yearly loss of lung function to about half the rate of continued smoking, in a large trial of smokers with early airway obstruction.
Compared with people who continued to smoke [15][16]; usual care, in the randomized comparison [16]; never smokers, with current and former smokers each set against them [17]
The numbers and sources
- Effect
- People who quit gained an average 47 mL (2%) of FEV1 in the year after quitting. Their later decline was 31 mL a year against 62 mL in continuing smokers [15]. At 11 years, men who quit lost 30.2 mL a year and women 21.5 mL, against 66.1 mL and 54.2 mL in continuing smokers. FEV1 was under 60% of predicted in 38% of continuing smokers and 10% of sustained quitters. The intervention group as randomized lost less lung function than usual care [16]. In pooled studies, COPD risk against never smokers was 3.51 (95% CI 3.08 to 3.99) in current smokers and 2.35 (95% CI 2.11 to 2.63) in ex-smokers, and limited data showed it falling with longer quitting [17].
- Population
- 3,926 smokers, mean age 48.5, with mild to moderate airway obstruction in 10 centers [15]. 77.4% of surviving participants at 11 years [16]. 133 studies of COPD [17].
- Sources
- [15], [16], [17]
- Caveats
- The comparison of quitters with continuing smokers is not randomized, since people chose whether to quit [15][16]. The pooled COPD estimates were markedly heterogeneous [17].
Cough and phlegm after switching
One trial found cough and phlegm fell more over a year with e-cigarettes than with nicotine replacement, with no difference in wheezing or shortness of breath.
Compared with nicotine replacement therapy [4]
The numbers and sources
- Effect
- From baseline to 52 weeks, the e-cigarette group had greater declines in cough (RR 0.8, 95% CI 0.6 to 0.9) and phlegm (RR 0.7, 95% CI 0.6 to 0.9) than the nicotine replacement group. Wheezing and shortness of breath did not differ [4].
- Population
- 886 adults at UK stop-smoking services [4].
- Sources
- [4]
- Caveats
- Symptoms were self-reported and participants knew their group. Part of the difference may come from more people quitting cigarettes in the e-cigarette group [4].
Lab markers
Lung disease and death from any cause
One UK cohort of 504,206 adults linked higher bilirubin within the usual range to less lung cancer, less chronic obstructive lung disease and fewer deaths.
The numbers and sources
- Effect
- For each 0.1 mg/dL higher bilirubin, the adjusted rate of lung cancer was 8% lower in men (95% CI 5% to 11%) and 11% lower in women (7% to 14%). In men the rate of chronic obstructive pulmonary disease was 6% lower (5% to 7%) and the death rate 3% lower (2% to 3%), with very similar results in women. Median bilirubin was 0.64 mg/dL in men and 0.53 mg/dL in women [8].
- Population
- 504,206 adults in a UK primary care database with no evidence of liver, bile duct or hemolytic disease, with 1,341 lung cancers, 5,863 cases of chronic obstructive pulmonary disease and 23,103 deaths [8].
- Sources
- [8]
- Caveats
- One cohort, observational, in people whose bilirubin was within the normal range [8]. Bilirubin was lower in active smokers in US survey data, so how fully smoking was accounted for matters to this result [5].