GLP-1 side effects: what the labels report, drug by drug

Every prescribing information carries a table of adverse reactions that occurred more often on the drug than on placebo in the weight-management trials. The figures below are those tables, read on DailyMed on September 23, 2026: the Wegovy label's Table 3 (2.4 mg weekly, 2,116 people against 1,261 on placebo), the Zepbound label's Table 1 (5, 10 and 15 mg weekly, about 630 to 950 people per dose against 958), and the Foundayo label's Table 1 (5.5, 9 and 17.2 mg daily, about 1,050 per dose against 1,576). Ozempic is the same molecule as Wegovy at lower doses and its label carries a diabetes-trial table instead; the weight-dose figures are Wegovy's.

Read each column on its own, against the placebo figure in its parentheses, never across a row. The Zepbound and Foundayo labels open their adverse-reactions sections with this sentence, and Wegovy's with the same words save "studies" for the second "trials": "Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice." The trials enrolled different people, ran for different lengths and counted reactions at different thresholds (Wegovy and Zepbound list anything at 2 percent, Foundayo at 5 percent), so a lower number in one column is not evidence that the drug is gentler.

The labels are specific about timing. Zepbound's: "The majority of nausea, vomiting, and/or diarrhea events occurred during dose escalation and decreased over time." Foundayo's: "The incidence of nausea, vomiting, and diarrhea was higher during the FOUNDAYO dosage escalation period and decreased over time." That is why every label sets a stepped schedule, and why a dose increase is the moment to expect the stomach to object. Our GLP-1 eating guide covers what to eat while it does.

The honest measure of how bad it gets is how many people quit. On Wegovy, 6.8 percent of adults permanently stopped because of adverse reactions against 3.2 percent on placebo, and the label names the reasons: nausea (1.8 versus 0.2 percent), vomiting (1.2 versus 0) and diarrhea (0.7 versus 0.1). On Zepbound the figures were 4.8, 6.3 and 6.7 percent at 5, 10 and 15 mg against 3.4 on placebo, most of them "during the first few months of treatment due to gastrointestinal adverse reactions". On Foundayo, 8 percent overall (6, 9 and 10 percent by dose) against 3 percent. Severe gastrointestinal reactions, a stricter category, were reported in 4.1 percent on the Wegovy injection against 0.9, 1.7 to 3.1 percent on Zepbound against 1, and about 3 percent on Foundayo against 1. All three labels say the drug is not recommended in people with severe gastroparesis, the condition where the stomach already empties slowly.

Each label's warnings section names the same set, and each one attaches a number. Acute pancreatitis: in the Wegovy weight trials it was confirmed in four treated patients, "0.2 cases per 100 patient years", against one on placebo; Zepbound's weight trials found it in 0.2 percent of treated patients (0.14 per 100 years of exposure) against 0.2 percent on placebo (0.15); Foundayo's in six patients (0.14 per 100 years) against one on placebo (0.04). Gallbladder disease: the Wegovy label reports gallstones in 1.6 percent of injection users against 0.7 on placebo and 2.5 percent of tablet users against 1, gallbladder inflammation in 0.6 against 0.2, and adds that the excess held "even after accounting for the degree of weight loss"; Zepbound's figures are 1.1 percent against 1 for gallstones, 0.7 against 0.2 for inflammation and 0.2 against none for gallbladder removal; Foundayo's are 1 against 0.7 and 0.4 against 0.3.

Acute kidney injury is the one to understand mechanically, because it follows from the common effects. All three labels report cases, "in some cases requiring hemodialysis", and say the majority "occurred in patients who experienced gastrointestinal adverse reactions leading to dehydration such as nausea, vomiting, or diarrhea". The trial rates: seven adults in the Wegovy weight trials (0.4 per 100 patient-years, against four on placebo, 0.2), 0.5 percent on Zepbound against 0.2, 0.2 percent on Foundayo against 0.05. The label instruction that follows is to keep drinking through a bad stretch and to report vomiting or diarrhea that persists, because that is the path from a nuisance to a kidney problem.

Three more carry numbers. Allergic reactions: the Zepbound label reports immediate hypersensitivity reactions in 2.1 percent against 0.4 and severe ones in 0.1 percent against none; Foundayo's reports 0.5 percent against 0.3 including anaphylaxis; all three labels say to stop the drug and seek care if one occurs, and all three make a prior serious reaction to the drug a contraindication. Low blood sugar: a real risk mainly in people with type 2 diabetes on insulin or a sulfonylurea, where Zepbound's label reports hypoglycemia in 10.3 percent of those on a sulfonylurea against 2.1 percent without one, and Foundayo's 7 percent against 0.5. Heart rate: the labels report mean heart-rate increases of 1 to 4 beats per minute on Wegovy, 1 to 3 on Zepbound and 4 to 5 on Foundayo; the Wegovy label adds that 26 percent of treated adults had a maximum increase of 20 beats or more at some visit against 16 percent on placebo, and says to discontinue for "a sustained increase in resting heart rate".

The black-box warning on Wegovy, Ozempic and Zepbound is about thyroid C-cell tumors, and it says exactly what is and is not known: in rodents the drug "causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures", and "It is unknown whether" the drug "causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans". Foundayo's box is worded differently because orforglipron "is not pharmacologically active in rats or mice and did not produce tumors in rodents", but the warning stays, since the human relevance of the rodent finding for the whole class "has not been determined". The practical parts are the same on every label: the drugs are contraindicated for anyone with a personal or family history of medullary thyroid carcinoma or with MEN 2; the symptoms to report are "a mass in the neck, dysphagia, dyspnea, persistent hoarseness"; and routine calcitonin blood tests or thyroid ultrasounds are "of uncertain value for early detection", which is the label's way of saying they are not a screening plan.

Section 17 of each label, the part written for the prescriber to tell the patient, gives the instructions in plain terms. Collected from the Wegovy, Zepbound and Foundayo labels:

• Stop the drug promptly and contact your physician for "severe abdominal pain that sometimes radiates to the back, and which may or may not be accompanied by nausea or vomiting" (Wegovy's wording; Zepbound and Foundayo say "may radiate to the back"), the symptom pattern of pancreatitis.
• Stop and seek medical advice promptly for symptoms of a hypersensitivity reaction, which the labels describe as anaphylaxis or angioedema (swelling of the face, lips, tongue or throat, trouble breathing).
• Contact your healthcare provider for "persistent (or extended) nausea, vomiting, and diarrhea" and for any signs of acute kidney injury, and "take precautions to avoid fluid depletion" in the meantime.
• Contact your provider for "severe or persistent gastrointestinal symptoms" and if gallbladder disease is suspected (section 17 does not list its symptoms; each drug's Medication Guide does: pain in the upper stomach, fever, yellowing of the skin or eyes, and clay-colored stools).
• Report "a lump in the neck, hoarseness, dysphagia, or dyspnea", the thyroid-tumor symptoms in the boxed warning.
• People with type 2 diabetes: report changes in vision, and report symptoms of low blood sugar if you also take insulin or a sulfonylurea.
• Wegovy only: report "palpitations or feelings of a racing heartbeat while at rest".
• Before any surgery or procedure: tell the team you take the drug, because it "may cause their stomach to empty more slowly which may lead to complications with anesthesia or deep sedation".

The Wegovy and Zepbound labels carry a "Recent Major Changes" list at the top, and it records a section titled "Suicidal Behavior and Ideation" as removed in February 2026. The labels state no reason there and this page does not supply one. What does not change is the response: thoughts of harming yourself are an emergency whatever medication you take, and in the United States you can call or text 988 at any hour.

Three things follow from the labels. First, the drug you are prescribed decides which table applies; our comparison of every approved GLP-1 lays out what each label reports for benefit. Second, a compounded semaglutide or tirzepatide has no label at all, so none of these numbers were measured for it; what the FDA says about compounded GLP-1s covers that gap, and the program directory shows which online programs sell compounded products and which sell only the labeled ones. Third, two effects people ask about most have their own guides: hair loss, which the labels report at 3 to 5 percent, and what happens if you stop, which the withdrawal trials measured.