GLP-1 side effects: what the labels list

The FDA labels of every GLP-1 medicine list the same kind of side effects first: nausea, diarrhea, vomiting, constipation and stomach pain, which happened most often while the dose was being increased. Every label also carries the same serious warnings: a boxed warning about thyroid C-cell tumors seen in rodents, plus pancreatitis, gallbladder disease, kidney injury from dehydration, severe stomach problems, allergic reactions, low blood sugar when combined with insulin or sulfonylureas, and food in the stomach during anesthesia.

This page compares what the labels of semaglutide (Wegovy, Ozempic and the tablets), tirzepatide (Zepbound, Mounjaro), liraglutide (Victoza, Saxenda), dulaglutide (Trulicity) and orforglipron (Foundayo) say. For one medicine in depth, see semaglutide, tirzepatide, liraglutide, dulaglutide or orforglipron. If you draw your dose from a vial, the semaglutide units calculator and the tirzepatide units calculator turn the dose your prescriber gave you into syringe units.

How often the common side effects occurred

Percent of people in the placebo-controlled trials pooled in each label, medicine versus placebo. A range covers the different doses in that label’s table.

Sources: section 6.1 of the Wegovy, Zepbound, Saxenda, Foundayo, Ozempic, Rybelsus and Ozempic tablets, Mounjaro, Victoza and Trulicity labels, checked October 16, 2026.

Don’t read this table as a ranking. Every label carries a version of this warning; the Wegovy label says: “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 studies of another drug and may not reflect the rates observed in practice.” The first four rows come from weight-management trials and the rest from type 2 diabetes trials, with different people and different doses, which is part of why the nausea rates differ.

Two Wegovy figures sit outside the table. In the 72-week trials of the 7.2 mg dose, nausea was 39% against 13% on placebo, and dysesthesia (an abnormal sense of touch) 22% against 0%. For Wegovy tablets, the label says “the types and frequency of common adverse reactions were similar” to the injection’s (Wegovy label, section 6.1).

Each label’s most common list

Every label’s highlights list the side effects reported by at least 5% of people. Nausea, diarrhea and vomiting are on all nine; the rest vary:

• Wegovy: also constipation, stomach pain, indigestion (dyspepsia), dysesthesia (an abnormal sense of touch), headache, fatigue, dizziness, bloating (abdominal distension), burping (eructation), gas, gastroenteritis, reflux, hair loss, and low blood sugar in people with type 2 diabetes.
• Zepbound: also constipation, stomach pain, indigestion, injection site reactions, fatigue, hypersensitivity reactions, burping, hair loss and reflux.
• Foundayo: also constipation, indigestion, stomach pain, headache, bloating, fatigue, burping, reflux, gas and hair loss.
• Saxenda: also constipation, stomach pain, injection site reactions, headache, low blood sugar, indigestion, fatigue, dizziness, increased lipase, fever and gastroenteritis.
• Mounjaro: also decreased appetite, constipation, indigestion and stomach pain.
• Rybelsus and Ozempic tablets: also stomach pain, decreased appetite and constipation.
• Victoza: also decreased appetite, indigestion and constipation.
• Trulicity: also stomach pain and decreased appetite.
• Ozempic injection: also stomach pain and constipation.

When they happen, and how often people stop

The labels agree that stomach side effects cluster around dose increases. Wegovy: “73% of WEGOVY injection-treated patients and 47% of patients receiving placebo reported gastrointestinal adverse reactions [...] These reactions were most frequently reported during dosage escalation.” Zepbound: “The majority of nausea, vomiting, and/or diarrhea events occurred during dose escalation and decreased over time.” Saxenda: “The percentage of patients reporting nausea declined as treatment continued.” Victoza: “Withdrawal due to gastrointestinal adverse events mainly occurred during the first 2 to 3 months of the trials.”

Most were not severe. Of people on Foundayo who had a stomach side effect, “60%, 36%, and 4% reported mild or moderate or severe adverse reactions, respectively.”

Source: section 6.1 of each label linked above.

Nausea: what the labels advise

The labels give one piece of practical advice about nausea, and it’s about fluids. The Zepbound Medication Guide says: “Diarrhea, nausea, and vomiting may cause a loss of fluids (dehydration) which may cause kidney problems. It is important for you to drink fluids to help reduce your chance of dehydration. Tell your healthcare provider right away if you have nausea, vomiting, or diarrhea that does not go away.” The Mounjaro, Ozempic and Rybelsus Medication Guides use the same words.

The other tool is the dose schedule itself. The Zepbound label has the dose increased step by step “to reduce the risk of gastrointestinal adverse reactions.” That schedule is your prescriber’s to set; if nausea is hard to live with, tell them rather than changing doses yourself.

What the labels don’t contain: diet tips. Advice such as smaller meals or avoiding fatty food is common, but none of the labels includes it, so ask your prescriber or pharmacist what fits you.

Nausea can also become serious. Severe stomach side effects were reported in 4.1% of people on Wegovy injection against 0.9% on placebo, 2% on Wegovy tablets against 0%, 4.8% on Saxenda against 1.4%, and 4.4% or 4.2% on Victoza against 1.1%. The Wegovy label says it “is not recommended in patients with severe gastroparesis.”

Hair loss, heart rate and other effects

• Hair loss. “Hair loss adverse reactions in WEGOVY injection-treated patients were associated with weight reduction”: 3.3% on the 2.4 mg dose (4% of women, 0.9% of men) against 1% on placebo. It was more common in women on Zepbound (7.1% against 0.5% of men; placebo 1.3% and 0%) and on Foundayo (7% against 0.9%; placebo 3% and 0.7%).
• Heart rate. Mean resting heart rate rose 1 to 4 beats per minute on Wegovy injection, 1 to 3 on Zepbound and 4 to 5 on Foundayo. On Foundayo, a fast heart rate (tachycardia) was reported in 3% against 0.9% on placebo. The Wegovy label asks patients to tell their provider about “palpitations or feelings of a racing heartbeat while at rest.”
• Low blood pressure. On Zepbound, hypotension “occurred more frequently among patients taking ZEPBOUND (1.6%) than patients taking placebo (0.1%).”
• Injection site reactions. On the most common lists of Zepbound and Saxenda.

The serious warnings on every label

The boxed warning. All nine labels carry “WARNING: RISK OF THYROID C-CELL TUMORS.” The Wegovy label explains: “In rodents, semaglutide causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures. It is unknown whether WEGOVY causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans.” People with a personal or family history of MTC or with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2) must not take it. The label adds that “Routine monitoring of serum calcitonin or using thyroid ultrasound is of uncertain value for early detection of MTC.”

The warnings and precautions, with section numbers that differ by label:

• Acute pancreatitis. Signs “may include persistent or severe abdominal pain (sometimes radiating to the back), and which may or may not be accompanied by nausea or vomiting” (Wegovy, section 5.2).
• Gallbladder disease. Gallstones (cholelithiasis) were reported in 1.6% on Wegovy injection against 0.7% on placebo, and gallbladder inflammation (cholecystitis) in 0.7% on Zepbound against 0.2%. Rapid weight loss raises gallstone risk, but on Wegovy acute gallbladder disease was more common than on placebo “even after accounting for the degree of weight loss.”
• Kidney injury from dehydration. Every label reports postmarketing cases of acute kidney injury, “in some cases requiring hemodialysis,” mostly in people who had nausea, vomiting or diarrhea “leading to dehydration.”
• Severe stomach side effects, covered above.
• Allergic reactions. “Serious hypersensitivity reactions (e.g., anaphylaxis, angioedema) have been reported” (Wegovy, section 5.7).
• Low blood sugar. The risk rises when a GLP-1 is combined with insulin or an insulin secretagogue, such as a sulfonylurea.
• Diabetic eye disease. On the labels of Wegovy, Ozempic, the semaglutide tablets, Zepbound, Mounjaro, Trulicity and Foundayo. In a 2-year trial in type 2 diabetes, retinopathy complications occurred in 3% on semaglutide injection against 1.8% on placebo; “Rapid improvement in glucose control has been associated with a temporary worsening of diabetic retinopathy.”
• Heart rate increase. A separate warning on Wegovy and Saxenda.
• Anesthesia. “There have been rare postmarketing reports of pulmonary aspiration” in people on GLP-1s having general anesthesia or deep sedation “who had residual gastric contents despite reported adherence to preoperative fasting recommendations” (Wegovy, section 5.10).
• Never share a pen between people: a warning of its own on the Wegovy, Ozempic and Zepbound labels.

The suicidal thoughts warning was removed

Older Wegovy, Saxenda and Zepbound labels had a warning about suicidal behavior and ideation. On January 13, 2026, the FDA asked for it to be removed: a meta-analysis of “91 placebo-controlled GLP-1 RA medication trials” with 107,910 patients “did not show an increased risk for SI/B or for other relevant psychiatric adverse events such as anxiety, depression, irritability, or psychosis.” The current labels show the section as “(Removed) 02/2026.”

The FDA still says: “Tell your health care professional if you experience new or worsening depression, suicidal thoughts, or any unusual changes in mood or behavior. Call or text 988” (FDA).

When to call your doctor

The Medication Guides turn the warnings into signs to watch for. Quoted from the Zepbound Medication Guide; the other labels warn about the same problems.

Tell your healthcare provider right away about:

• Gallbladder symptoms: “pain in your upper stomach (abdomen),” “fever,” “yellowing of skin or eyes (jaundice),” “clay-colored stools.”
• Dehydration: “nausea, vomiting, or diarrhea that does not go away.”

Tell your healthcare provider about:

• Thyroid signs: “a lump or swelling in your neck, hoarseness, trouble swallowing, or shortness of breath.”
• Stomach problems “that are severe or will not go away.”
• Changes in vision during treatment.
• Surgery or procedures: “Tell all your healthcare providers that you are taking ZEPBOUND before you are scheduled to have surgery or other procedures.”

And for everything else: “Talk to your healthcare provider if you have any side effect that bothers you or that does not go away.” You can report side effects to the FDA at 1-800-FDA-1088.

What’s known long term

Large outcome trials have followed people on GLP-1s for about 2 to 5 years. Most were designed to test heart or kidney outcomes, and they recorded side effects along the way.

SELECT, SUSTAIN-6, SOUL and LEADER were funded by Novo Nordisk (LEADER also by the NIH); REWIND, SURPASS-CVOT, SURMOUNT-1 and ACHIEVE-4 by Eli Lilly. In SELECT, weight loss “was sustained for up to 4 years,” with a mean 10.2% loss at 208 weeks against 1.5% on placebo, and semaglutide “was associated with fewer serious adverse events” (Nat Med).

Three limits matter:

• Beyond about 5 years, there’s little trial data. The longest median follow-up here is REWIND’s 5.4 years.
• Some questions stay open. Whether these medicines cause thyroid cancer in humans “is unknown” (Wegovy, section 5.1), and the Wegovy label says “The effect of long-term glycemic control with semaglutide on diabetic retinopathy complications has not been studied.”
• SELECT recorded only some side effects. “Safety data collection was limited to serious adverse events (including death), adverse events leading to discontinuation, and adverse events of special interest” (Wegovy, section 6.1).

What happens after stopping was studied too. In the STEP 1 extension, people who stopped semaglutide 2.4 mg after 68 weeks “regained two-thirds of their prior weight loss” by week 120, and “Cardiometabolic improvements [...] reverted towards baseline at week 120 for most variables” (Diabetes Obes Metab).

Questions people ask