Stomach and gut

Shown to cause one or more discontinuation symptoms in 12.1% after abruptly stopping extended-release quetiapine, against 6.7% after stopping placebo.

Gastrointestinal side effects ran 2% to 23% on berberine against 2% to 15% on placebo, with no serious adverse events reported in 16 trials.

Shown to raise nausea to 40% against 1.3% on placebo, along with flushing, headache and vomiting. Most events were mild to moderate and passed.

Shown to raise stopping for side effects to 18% against 2% on placebo, most often because of nausea.

Shown to raise dry mouth, nausea, dizziness, tremor, sweating and ringing in the ears against placebo, with dry mouth in 17% to 24% against 7%.

Shown to raise diarrhea, vomiting, fatigue, sleepiness and loss of appetite in seizure trials, with 14% against 1% withdrawing for side effects.

Shown to raise stomach side effects, with nausea in 21% on 1.5 mg against 5% on placebo and vomiting in 13% against 2%.

Shown to raise the odds of insomnia fivefold and jitteriness 3.5-fold against controls, in pooled studies, with insomnia reported by about a quarter of adult drinkers.

Shown to raise dizziness to 29% against 8%, nausea to 28% against 9%, and vertigo to 23% against 3% in esketamine trials.

Shown to raise dizziness, double vision, unsteadiness and nausea when added to other seizure drugs, with dizziness in 38% against 13% on placebo.

Shown to raise nausea, insomnia, fatigue and back pain slightly in bipolar trials, with nausea in 14% against 11% on placebo. Overall adverse effects matched placebo.

Shown to raise vivid dreams about 2.4 times over placebo, with adverse events overall 1.4 times as frequent. Serious adverse events did not differ.

Diarrhea and other gut effects were reported in 11 to 37% on oral magnesium against 10 to 14% on control in cramp trials.

Shown to cause dry mouth in 25% against 15% on placebo, constipation in 13% against 7% and dizziness in 7% against 3%.

Shown to raise nausea, 11% on modafinil against 3% on placebo, along with smaller rises in appetite loss, dry mouth and diarrhea. 8% stopped for side effects.

Shown in label trials to cause side effects at rates close to placebo, with headache in 18.4% on montelukast against 18.1% on placebo.

Shown to raise side effects in women taking NSAIDs for period pain, from 10% on placebo to between 11% and 14%, mostly gut and nervous system effects.

Shown to raise fatigue and constipation against placebo in chemotherapy trials, with fatigue in 13% against 2% and constipation in 9% against under 1%.

Shown to raise gut side effects to about 60 to 69% against 37% on placebo, with 8% stopping for side effects against 3%.

Shown in label trials to raise headache, diarrhea and dizziness against placebo, with headache in 12.2% on pantoprazole against 8.5% on placebo.

Linked to about twice the odds of small intestinal bacterial overgrowth, found in 36.8% of users studied against 19.9% of controls, rising with longer use.

Shown to raise diarrhea and nausea, the most common side effects, more at higher doses. In diabetes, diarrhea reached 34% against 13% on placebo.

Shown to raise nausea and diarrhea, mostly mild to moderate. Stopping for stomach effects was 4.5% against 0.8% on placebo in one trial.

Shown to raise nausea, dry mouth, sweating, constipation and dizziness against placebo, with nausea in 23% to 30% against 8% to 12% on placebo.

Shown to raise nausea, diarrhea, tremor and sweating against placebo, with nausea in 26% on sertraline against 12% on placebo.

Shown to cause tingling in about half of people at 100 mg, 51% against 6% on placebo, along with appetite loss, taste change, nausea and diarrhea.

Shown to raise dry mouth, blurred vision, swelling and fatigue against placebo, with dry mouth in 34% of outpatients against 20% on placebo.

Limited evidence: in epilepsy trials, constipation was reported in about 17%, lethargy in 11% and loss of appetite in 12% on the modified Atkins diet.

Limited evidence: in people with cirrhosis, nausea and diarrhea occurred in 12% on BCAAs against 3% on control, with a very uncertain estimate.

One small trial found mild nausea or diarrhea in 7 of 52 patients during coumarin, which stopped after the first month.

Limited evidence: in 20 adults on levothyroxine, 1,200 mg of calcium carbonate lowered free T4 and raised TSH, which returned after stopping calcium.

The clonidine tablet label reports dry mouth in about 40 of 100 people, dizziness in 16 and constipation in 10, mostly dose-related and easing over time.

One trial found gut side effects such as indigestion and gastritis-like symptoms in 35% on dabigatran 150 mg against 24% on warfarin.

Small trials found more adverse events on dasatinib plus quercetin, 82% against 43% on placebo in one, all self-limiting.

One trial found advanced colorectal lesions in 11.6% on 1 mg a day against 6.9% on placebo, in people with past adenomas.

Limited evidence: gastrointestinal problems were the most common side effect in children treated for epilepsy, reported in 40.6% across 45 studies.

One trial found 44% of healthy volunteers had acid-related symptoms after stopping 8 weeks of a proton pump inhibitor, against 15% after placebo.

Small trials found mouth sores, rash and gut problems in a few older adults, and falls in red cell counts without clinical effects.

Limited evidence: about 35% reported mild, brief stomach symptoms in small trials without placebo.

Shown to raise side effects such as diarrhea, vomiting and rash against placebo, one extra person affected for every 8 to 24 treated, depending on the infection.

Shown to raise major bleeding by about 43% against no aspirin, to 4.1% against 3.2% over 7.4 years in one trial and 3.8% against 2.8% in another.

Shown to raise stomach and gut bleeding by about 25% against warfarin across the class, with the rise seen on rivaroxaban and not on apixaban.

Shown to raise nausea, vomiting, diarrhea and constipation about threefold over placebo, mostly mild to moderate and early. Stopping for side effects rose at higher doses.

Shown to cause constipation on verapamil, reported by 7.3% of people in its trials. The label gives no placebo rate.

Shown to raise constipation to 6% to 8% on atogepant against 2%, and to 3% on erenumab 140 mg against 1%. The erenumab label warns of serious cases.

Shown to raise nausea on gepants, 9% on atogepant 60 mg against 3%, and 2% to 4% on rimegepant or ubrogepant against under 1% to 2%.

Linked to about 2.4 times the major bleeding when an NSAID was taken alongside an anticoagulant, and to 3.1% against 1.9% when rivaroxaban was added to aspirin.

The labels report headache, dizziness and constipation in 1% or more on famotidine. On cimetidine 1,600 mg a day, headache occurred in 3.5% against 2.3% on placebo.

Shown to raise gastrointestinal bleeding or perforation, 2.9% against 2.0% on placebo, mainly in hospital patients. Ulcer risk was far higher with an NSAID.

Linked to about 1.7 times the odds of C. difficile infection in observational studies. In a 3-year trial, enteric infections were 1.4% on pantoprazole against 1.0% on placebo.

Shown to cause dizziness in 5.0% on glimepiride against 2.4% on placebo and nausea in 5.0% against 3.4%, with diarrhea in 5.4% on glipizide against none.

Shown to cause drowsiness in 8% against 5% on placebo and dizziness in 5% against 1% in zolpidem trials lasting 28 to 35 nights.

Limited evidence: in a self-report survey, 3.1% to 5.5% reported digestive symptoms, and fewer reported muscle or skin symptoms.

Case series: after removal of a bowel segment for deep endometriosis, rectovaginal fistula averaged 2.3% to 3.6%, anastomotic leak 1.7% and urinary retention about 5%.

Limited evidence: trials of excision or ablation for mild disease reported few complications, 3 minor ones among 172 women in the largest.

Shown to about double stomach and gut bleeding on aspirin, 0.97% against 0.46% on placebo over five years in one trial.

Shown to raise gallbladder and bile duct disease about 37% across GLP-1 drug trials. In REWIND, serious acute cholecystitis occurred in 0.5% on dulaglutide against 0.3%.

Acute pancreatitis occurred in 0.22% of trial participants, with no difference between doses.

A global meta-analysis found 1.5% of the general population tested positive for celiac antibodies and 0.8% had celiac disease confirmed by biopsy.

One trial found severe rash in 0.26% on clopidogrel against 0.10% on aspirin, and severe diarrhea in 0.23% against 0.11%.

One trial found slightly more pancreatitis on fenofibrate than placebo, 0.8% against 0.5%, over 5 years. The label reports pancreatitis with fibrates.

Linked to about 40% higher odds of serious bleeding in observational studies, roughly one extra upper gut bleed per 3,177 low-risk people treated.

FDA states olmesartan can cause sprue-like enteropathy, with severe chronic diarrhea and weight loss months to years after starting. A French cohort linked it to malabsorption admissions.

Shown to raise stomach and intestinal bleeding with all NSAIDs, about 2 to 4 times, rising with dose and age. Celecoxib had fewer events.

Linked to about nine times the lung cancer risk of never smoking in pooled studies, and to raised risks of cancers of the larynx, throat, mouth and esophagus.

Linked to C. difficile infection outside hospital, about 2.7 times the odds on penicillins or macrolides and 5.7 on cephalosporins, with no link for tetracyclines.

Shown to change the gut microbiome, often lowering bacterial diversity and beneficial bacteria, with some changes lasting a year or more after certain antibiotics.

Reported side effects included flatulence, nausea and headache, with no major health risks across 54 studies.

Shown to raise racing heart, anxiety, insomnia, gut upset and headache in athletes, with several rising with dose.

Long-term trials reported constipation, diarrhea and soft stools. Adverse events were about as common with CLA plus exercise as with exercise alone.

A systematic review of trials found most adults with lactose intolerance or malabsorption tolerated 12 to 15 g of lactose, about one cup of milk.

Shown to raise mild adverse events in children, with rash in 7.1% of treated infections against 2.7% on placebo in one trial.

Shown to raise flatulence over control in adults with chronic constipation.

Shown to raise diarrhea and upper digestive symptoms in Crohn's disease trials, with no serious adverse events recorded.

Weight loss trials reported abdominal discomfort, diarrhea and constipation. In a pediatric trial, adverse events were about as common as on placebo.

Shown to cause more gastrointestinal adverse events than lower-protein diets across trials.

Gut upset was slightly more common than on placebo in mood disorder trials, and less common than on metformin in PCOS.

Shown to raise gut side effects with ferrous sulfate, about 2.3 times the odds on placebo, in adults.

Across GLP-1 drug trials, shown to raise gallbladder and bile duct disease about 37%, and more in weight loss trials, at higher doses and with longer use.

Linked to gut side effects more often in women than men on metformin, at about 1.85 times the odds.

Shown to raise stopping for side effects about 1.6 times over placebo, a 3% absolute difference, mostly from gut effects.

Linked to more fundic gland polyps with use of a year or longer, and to about 1.4 times the risk of stomach cancer in a few observational studies.

IARC classifies processed meat as causing colorectal cancer, with risk up 18% per daily 50 g portion. A 2019 review rated the link very small and low certainty.

Shown to raise gallbladder and bile duct disease about 37% across GLP-1 drug trials, more at higher doses and longer use. The analysis pooled all GLP-1 drugs.

Linked to more bleeding when combined: about 4 times the odds of an upper gut bleed with an NSAID, and about a third more major bleeds with anticoagulants.

Linked to about twice the odds of stomach and gut bleeding when an NSAID was taken with warfarin, compared with warfarin alone.

Shown to raise minor side effects such as unpleasant taste and nausea about 34% when used to treat colds.

Linked to more deaths, cardiovascular events, gastrointestinal bleeds and kidney function loss at higher doses in cohort studies of regular users.

FDA requires over-the-counter acetaminophen labels to warn of severe liver damage, and NSAID labels of stomach bleeding, with 3 or more drinks every day.

Limited evidence: in dialysis patients, 5 of 17 stopped calcium AKG within 2 weeks for stomach and bowel upset. Trials of related AKG salts reported them well tolerated.

One trial found nausea, vomiting and vertigo rose with dose from 600 to 1,800 mg a day over 5 weeks.

The label names thyroid medication, guanethidine, anticholinergic drugs and epinephrine with local anesthetics as combinations that need close supervision. It gives no rates.

The doxycycline label warns of exaggerated sunburn, irritation and ulcers of the esophagus, and raised pressure inside the skull, which can threaten vision.

The labels warn that alcohol and other sedatives add to antihistamine drowsiness, ritonavir raised cetirizine levels by 42%, and fexofenadine's label says not to take it with fruit juice.

The labels warn that NSAIDs raise the risk of bleeding with either drug. A small study found ibuprofen taken before aspirin blocked aspirin's effect on platelets.

The label states that opioids delay and reduce the absorption of clopidogrel, lowering exposure to its active metabolites. It gives no outcome rate.

The aspirin label lists indigestion, raised liver enzymes, hepatitis and Reye's syndrome among adverse reactions. It gives no rates.

One small study found 30 ml of ACV with a meal slowed stomach emptying in 10 adults with type 1 diabetes and gastroparesis.

Case reports: one person had throat injury from an ACV tablet. Tests of 8 tablet brands found wide variation and doubt that ACV was in them.

Small trials found more frequent stools, cramps, nausea and headaches on bacopa than placebo, with no serious reactions.

The labels warn that calcium and antacids block alendronate absorption, aspirin added gut side effects, and aminoglycosides or loop diuretics may lower calcium further with zoledronic acid.

Case reports: a 61-year-old man on a carnivore diet developed acute pancreatitis caused by severe hypertriglyceridemia.

Case reports: tears of the rectum after colonic irrigation by alternative practitioners, leading to pelvic abscesses, surgery and colostomy.

An outbreak investigation linked at least 36 cases of amebiasis to colonic irrigation at one clinic, where the machine stayed contaminated after routine cleaning.

Case reports: colitis and rectal burns after coffee enemas, and deaths in two people who used them very often, with low sodium and chloride at autopsy.

Small crossover studies found milk and yogurt cut ciprofloxacin absorption by 30% to 36%, and milk cut tetracycline absorption by 65%.

The label reports pancreatitis at 3.4 per 1,000 patient-years on dulaglutide against 2.7 on other drugs, and pancreatic enzyme rises of 14% to 20%.

The label reports rare cases of pulmonary aspiration during anesthesia or deep sedation in people on GLP-1 drugs, with food still in the stomach despite fasting.

The label states dulaglutide slows stomach emptying and may slow absorption of oral medicines, though 1.5 mg did not change tested drugs to a clinically relevant degree.

Case reports: rare allergic reactions, which may be severe. Gastrointestinal upset and rash were the most frequent adverse events reported.

FDA expected its egg safety rule to prevent about 79,000 illnesses and 30 deaths a year from eggs contaminated with Salmonella Enteritidis.

Case reports: 11 of 25 people had nausea and vomiting after drinking juice from wild elderberries crushed with leaves and stems. All recovered.

The label warns fenofibrate, like other fibrates, may raise cholesterol in bile and lead to gallstones.

Small trials found mild gut side effects in some studies, with no liver or kidney toxicity or severe adverse events.

Linked to about 50% higher stomach cancer risk in a meta-analysis of 60 studies of pickled vegetables, mostly from Korea, China and Japan.

Case reports: a woman with an esophageal web had her esophagus blocked after taking a glucomannan diet aid.

The label reports that an antacid containing aluminum and magnesium hydroxides lowered the amount of gabapentin absorbed by about 20%.

Case reports: esophageal blockage after a glucomannan diet aid, and stomach outlet blockage linked to konjac flour noodles.

Limited evidence: across phlebotonic trials, adverse events were slightly more common than on placebo, mostly digestive. Only one trial tested grape seed extract.

The FDA states grapefruit juice can interact with budesonide. One small study in 8 men found juice for 4 days about doubled its bioavailability.

Linked to five times the esophageal cancer risk when burning-hot tea was combined with 15 g or more of alcohol a day, in one large Chinese cohort.

Case reports: a woman taking only water and green tea catechin supplements for 2 weeks developed severe pancreatitis and suspected toxic hepatitis.

Small studies in healthy men found the acid-lowering effect of famotidine and ranitidine fell within 5 to 14 days of continuous daily dosing.

The famotidine label warns it can lower absorption of drugs that need stomach acid and may sharply raise tizanidine levels. It gives no rate.

One small trial found more digestive intolerance on iodine in pregnant women.

Case reports: a review found 25 published cases of pancreatitis on isotretinoin, 4 likely due to high triglycerides. No rate could be given.

One trial found 16 serious adverse events on lactoferrin against 10 on sucrose in very preterm infants, 2 judged possibly related.

Limited evidence: in one trial four people dropped out for abdominal discomfort, nausea and rash. Trials were too small to estimate rates.

Small trials found an aluminum and magnesium antacid taken up to 4 hours before ciprofloxacin cut its absorption. Taken 6 hours before or 2 hours after, it did not.

Case reports: 17 cases of volvulus in premature infants after abdominal massage, 4 of them fatal, in a review of 60 pediatric massage studies.

Limited evidence: one trial reported more gallbladder disease and urinary incontinence during estrogen plus progestin, with most risks fading after stopping.

Limited evidence: gut and urinary effects were the most common reasons for stopping a related compound. The label warns it interferes with pulse oximetry readings.

Limited evidence: at antidote doses for acetaminophen poisoning, acetylcysteine has caused reactions from nausea to death, and intravenous dosing anaphylaxis-like reactions.

One trial found more serious gut, muscle, skin, infection and bleeding events with niacin plus laropiprant. EMA suspended these products in 2013.

One trial found saccharin and sucralose for 2 weeks impaired glucose tolerance against controls, with changes in gut bacteria that varied from person to person.

The label warns ondansetron can mask a worsening ileus or stomach distension after abdominal surgery or chemotherapy. It gives no rate.

The label warns of thyroid C-cell tumors seen with related drugs in rodents, with human relevance not determined. Pancreatitis and gallstones were slightly more common.

The label caps the dose at 9 mg with strong CYP3A4 inhibitors, says to avoid some others, and notes it may affect absorption of other oral medicines.

The label warns orlistat can reduce the effect of drugs such as cyclosporine, levothyroxine and warfarin, and reduce absorption of some fat-soluble vitamins.

One study in mice and people found a multi-strain probiotic delayed the gut microbiome's return after antibiotics, compared with spontaneous recovery.

IARC classifies red meat as probably causing cancer, on limited evidence in people, mainly for colorectal cancer, with links also to pancreatic and prostate cancer.

One trial at up to 1,000 mg twice daily found nausea, diarrhea and weight loss, and more brain volume loss than placebo in Alzheimer disease.

Linked to stomach cancer in cohorts, with 68% higher risk at high against low intake. A salt substitute trial found a nonsignificant trend toward fewer stomach cancers.

Case reports: death and brain bleeding appeared in isolated reports with questionable causality. Stomach upset, headache and lower libido were the most often reported effects.

Case reports: 201 people who took a supplement with 200 times its labeled selenium had diarrhea, fatigue, hair loss and nail changes.

The labels warn that NSAIDs, aspirin, warfarin and other anticoagulants may add to bleeding risk, and report increased bleeding with warfarin. They give no rate.

The label warns that tirzepatide lowers birth control pill levels and tells users to switch to or add a non-oral method for 4 weeks after starting and each dose increase.

The label lists hepatitis and raised liver enzymes, allergic reactions, rash, hair loss, nausea and diarrhea among other adverse reactions. It gives no rates.