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Every guide

Grouped the way people usually ask: what's common, what's serious, what mixes badly, and what to do before a procedure.

Common

The everyday side effects most people notice, and how long they tend to last.

Infographic titled Semaglutide side effects in plain numbers, from Wegovy 2.4 mg weight-loss trials. Nausea 44% vs 16% on placebo, diarrhea 30% vs 16%, vomiting 24% vs 6%, constipation 24% vs 11%, stomach pain 20% vs 10%. Less common: severe stomach side effects 4.1% vs 0.9%, gallstones 1.6% vs 0.7%, stopped because of side effects 6.8% vs 3.2%.

Reviewed Oct 19, 2026

Semaglutide side effects: what's common, what's serious

Nausea and the other everyday effects, the rare warnings, and the signs that mean you should call, all taken from the FDA labels.

Infographic titled Tirzepatide side effects by dose, from Zepbound weight-loss trials. Share of adults on placebo, 5 mg, 10 mg and 15 mg: nausea 8%, 25%, 29%, 28%; diarrhea 8%, 19%, 21%, 23%; vomiting 2%, 8%, 11%, 13%; constipation 5%, 17%, 14%, 11%. Side panel: any stomach or gut side effect 56% at each dose vs 30% on placebo; stopped because of side effects 4.8%, 6.3%, 6.7% vs 3.4%; severe stomach side effects 1.7%, 2.5%, 3.1% vs 1%.

Reviewed Oct 19, 2026

Tirzepatide side effects, dose by dose

Nausea, diarrhea and the other common effects at each dose, the rare warnings, and the 2026 label changes, all taken from the FDA labels.

Infographic titled GLP-1 nausea: how long it lasts. Median length of one bout on semaglutide 2.4 mg in 68-week trials: nausea 8 days, diarrhea 3 days, vomiting 2 days, constipation 47 days vs 35 on placebo; bouts of nausea, diarrhea and vomiting were about as long on placebo. Nausea by label, medicine vs placebo: Wegovy 2.4 mg 44% vs 16%, Zepbound 10 mg 29% vs 8%, Ozempic 1 mg 20.3% vs 6.1%, Mounjaro 15 mg 18% vs 4%. A timeline of Wegovy dose steps (0.25, 0.5, 1 and 1.7 mg for 4 weeks each, then 2.4 mg maintenance) marks about week 20, when nausea, diarrhea and vomiting peaked before declining. Stopped Wegovy for stomach side effects: 4.3% vs 0.7%.

Reviewed Oct 19, 2026

GLP-1 nausea: how long it lasts, and when to call

How often nausea happens on each medicine, why it peaks while the dose goes up, what the labels advise, and the signs that mean it's something more.

Infographic titled Ozempic hair loss, in plain numbers. Share of adults with hair loss in weight-loss trials, by dose. Wegovy (semaglutide), in the 7.2 mg trials: 1.0% on placebo, 3.3% on 2.4 mg, 5.8% on 7.2 mg. Zepbound (tirzepatide): 1% on placebo, 5% on 5 mg, 4% on 10 mg, 5% on 15 mg. Ozempic and Mounjaro, at diabetes doses, list hair loss only in reports received after approval, with no trial rate. Mostly women: 7.1% of women vs 0.5% of men on Zepbound, 8.4% vs 0.2% on Wegovy 7.2 mg, and 1.3% vs 0% on placebo in the Zepbound trials. Shedding after weight loss starts a few months later, and fullness tends to return within 6 to 9 months.

Reviewed Oct 19, 2026

Ozempic hair loss: how common it is, and why weight loss plays a part

What the semaglutide and tirzepatide labels report about hair loss, who notices it most, and what the evidence says about getting your hair back.

Serious

Rare but important warnings, with the signs that mean you should get help.

Infographic titled Ozempic and stomach paralysis: the evidence. Left panel, a 2025 insurance-claims study of adults with obesity and no type 2 diabetes: new gastroparesis diagnoses per 1,000 person-years were 6.5 on semaglutide (36,990 people), 2.1 on bupropion-naltrexone (7,369 people) and 1.1 after sleeve gastrectomy (11,101 people), based on diagnosis codes, not stomach-emptying tests. Right panel, from the Ozempic label: severe stomach side effects in trials 0.4% on 0.5 mg and 0.8% on 1 mg vs 0% on placebo; not recommended in severe gastroparesis, a warning updated Oct 2025; gastroparesis is not listed as a side effect, while reports since approval include ileus and intestinal obstruction. Bottom strip: label trial data, randomized with placebo; claims studies, a signal, not proof; lawsuits, allegations only; lasting paralysis after stopping, not established.

Reviewed Oct 19, 2026

Ozempic and stomach paralysis: what's known, what isn't

The label's wording on severe stomach problems, why semaglutide slows the stomach, what claims-database studies found, and what the lawsuits do and don't show.

Infographic titled GLP-1 pancreatitis risk, in plain numbers. Confirmed cases per 100 years of treatment, medicine vs comparator: tirzepatide in diabetes trials 0.23 vs 0.11, Ozempic 0.3 vs 0.2, Wegovy 0.2 vs less than 0.1. In the Zepbound weight-loss trials, 0.2% on Zepbound and 0.2% on placebo. UK reports from 2007 to October 2025: 1,296 reports of pancreatitis, 19 fatal. The warning sign: severe belly pain that won't go away, sometimes felt in your back, with or without nausea or vomiting.

Reviewed Oct 19, 2026

GLP-1 pancreatitis risk: what the trials found, and the signs to know

How often pancreatitis showed up in the trials, why your lipase result may rise, and the belly pain that means you should stop and call.

Infographic titled The Ozempic thyroid cancer warning, from rats to people. Rats and mice: thyroid C-cell tumors at clinically relevant exposures. Monkeys: no C-cell overgrowth after 20 months of liraglutide. People: mixed but mostly reassuring, and the risk in humans is unknown. A Scandinavian study found 1.33 thyroid cancers per 10,000 person-years on GLP-1 medicines vs 1.46 on DPP-4 inhibitors, hazard ratio 0.93. A French study found a hazard ratio of 1.58 after 1 to 3 years of use. Not for anyone with a personal or family history of medullary thyroid cancer, or MEN 2. Report a neck lump, hoarseness, trouble swallowing or shortness of breath.

Reviewed Oct 19, 2026

The Ozempic thyroid cancer warning: what it's based on, and what it means for you

Why semaglutide and tirzepatide carry a boxed warning about thyroid tumors, what large studies in people have found, and the neck symptoms to report.

Infographic titled Semaglutide and NAION: where things stand. A timeline: Oct to Dec 2024, the FDA lists NAION as a potential safety signal for GLP-1 medicines. Jun 6, 2025, Europe's EMA calls NAION a very rare side effect of semaglutide. Jun 27, 2025, WHO issues an alert. Feb 5, 2026, the UK MHRA updates its advice. Oct 2026, the US labels still do not list NAION. A side panel, labeled a signal from observational studies, reads: up to 1 in 10,000 people taking semaglutide (EMA), about 1 extra case per 10,000 person-years of treatment in type 2 diabetes (EMA), and 123 vs 67 cases per 100,000 person-years on semaglutide vs an SGLT2 inhibitor in US veterans.

Reviewed Oct 20, 2026

Semaglutide and NAION: what we know about the eye risk

A rare optic nerve condition, a signal from observational studies, and regulators who have read it differently. Here's where things stand in October 2026.

Infographic titled GLP-1 gallbladder problems in plain numbers. Gallstones in adult weight-loss trials, medicine vs placebo: Wegovy injection 1.6% vs 0.7%, Wegovy tablets 2.5% vs 1%, Saxenda 2.2% vs 0.8%, Zepbound 1.1% vs 1%. Gallbladder inflammation: Wegovy 0.6% vs 0.2%, Zepbound 0.7% vs 0.2%, Saxenda 0.8% vs 0.4%. Teens on Wegovy: gallstones 3.8% vs 0%. Signs to report: upper stomach pain, fever, yellow skin or eyes, clay-colored stools.

Reviewed Oct 20, 2026

GLP-1 gallbladder problems: how common are gallstones?

What the FDA labels report about gallstones and gallbladder inflammation, how weight loss plays a part, and the signs that mean you should call.

Reviewed Oct 20, 2026

Compounded semaglutide dosing errors: what the FDA has seen

Why measuring your own dose from a vial can go wrong, what the FDA and US poison centers have reported, and who to call if you think you took too much.

Infographic titled Retatrutide side effects, from the trials. Labeled not approved, investigational. TRIUMPH-1, 80 weeks, retatrutide 12 mg vs placebo as reported by Lilly: nausea 42.4% vs 14.8%, diarrhea 32.0% vs 13.5%, constipation 26.1% vs 10.9%, vomiting 25.3% vs 4.8%, dysesthesia (skin sensations) 12.5% vs 0.9%. Stopped because of side effects, 12 mg vs placebo: 11.3% vs 4.9% in TRIUMPH-1, 18.2% vs 4.0% in TRIUMPH-4 (adults with knee arthritis) and 13.5% vs 4.8% in TRIUMPH-3 (severe obesity and heart disease). Status: not approved by any regulator; Lilly plans to apply to the FDA in early 2027.

Reviewed Oct 20, 2026

Retatrutide side effects: what the trials have reported

Retatrutide is an investigational drug, not approved anywhere. Here is what its trials have reported about side effects so far, and why products sold online are a different risk.

Interactions

How GLP-1 medicines get along with other medicines, birth control and alcohol.

Infographic titled Tirzepatide and the pill: when you need backup. A timeline example, with the dose going up every 4 weeks from 2.5 mg to 5, 7.5, 10, 12.5 and 15 mg, shows a 4-week backup window after starting and after each increase, joining up from week 0 to week 24. After a first 5 mg dose, the peak level of the estrogen in a combined pill fell by 59% and total exposure over time by 20%. Pill users should switch to a non-oral method, or add a barrier method such as condoms, for 4 weeks after starting and 4 weeks after each dose increase. The label says hormonal methods not taken by mouth, such as a hormonal IUD, implant, shot, patch or ring, should not be affected. Wegovy and Ozempic labels carry no birth control advice.

Reviewed Oct 20, 2026

Tirzepatide and birth control: what the label says about the pill

Why tirzepatide can weaken birth control pills, the 4-week backup windows on the label, and what to do if you're vomiting or planning a pregnancy.

Infographic titled Alcohol and your GLP-1: where the risks overlap. Three rows. Low blood sugar: 6.2% on Wegovy vs 2.5% on placebo in adults with type 2 diabetes, and alcohol can hide the early signs. Pancreatitis: a label warning, and heavy drinking is one of its most common causes. Stomach upset: nausea in 20.3% on Ozempic 1 mg vs 6.1% on placebo, and vomiting 9.2% vs 2.3%. A side card says what the labels say about drinking: nothing. There is no alcohol warning in the US labels for Ozempic, Wegovy, Rybelsus, Mounjaro or Zepbound, which does not make it safe.

Reviewed Oct 20, 2026

Drinking alcohol on Ozempic or another GLP-1

The labels don't mention alcohol. Here's where drinking overlaps with the risks they do list, and what research says about GLP-1s and the urge to drink.

Procedures

What to tell your care team before surgery, sedation or a scope.

Infographic titled GLP-1 before surgery: how the advice changed. Timeline: Jun 29, 2023, anesthesiologists suggest holding it, the day of surgery for daily doses or a week before for weekly doses. Oct 29, 2024, five societies say most people can keep taking it, with a plan made with your care team. Nov 1, 2024, the FDA adds an aspiration warning to the Ozempic and Wegovy labels. May 2025, a perioperative society advises 24 hours of clear liquids only before anesthesia. A side panel lists what raises the risk: still raising your dose, a higher dose, a weekly shot, stomach symptoms like nausea or belly pain, and other conditions that slow the stomach.

Reviewed Oct 20, 2026

Taking a GLP-1 before surgery or sedation

Why a slower stomach matters under anesthesia, how the advice changed from 2023 to now, and what your care team may do on the day.