GLP-1 Side Effects Comparison Chart (2026 FDA Label Data)
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GLP-1 side effects are mostly digestive — nausea, vomiting, diarrhea, constipation, reflux, and burping — but the rates differ a lot by drug, dose, and reason for taking it. This GLP-1 side effects comparison chart pulls the numbers straight from each drug's current FDA prescribing information. In weight-loss-dose trials, Wegovy injection, Wegovy HD, Foundayo, Saxenda, and Zepbound show the highest digestive side effect rates, with nausea hitting 28% to 44% of patients. In diabetes-dose trials, rates are meaningfully lower.
The GLP-1 Side Effects Comparison Chart
Common GI side effects across all FDA-approved GLP-1 drugs
| Drug (active ingredient, dose) | FDA-approved use | Route | Nausea | Vomiting | Diarrhea | Constipation | Overall GI rate (vs. placebo) | Stopped due to GI |
|---|---|---|---|---|---|---|---|---|
| Wegovy injection (semaglutide 2.4 mg weekly) | Obesity, CV risk, MASH | Weekly shot | 44% | 24–25% | 30% | 24% | 73% vs. 47% | 4.3% vs. 0.7% |
| Wegovy HD (semaglutide 7.2 mg weekly) | Obesity | Weekly shot | 39% | 22% | ≥5% (see label) | 20% | ≥5% (see label) | 3% vs. 0.3% |
| Wegovy tablets (semaglutide 25 mg daily) | Obesity, CV risk | Daily pill | Similar to injection | — | — | — | Severe GI ~2% (vs. ~4% injection) | 3.4% vs. 2% |
| Foundayo (orforglipron 17.2 mg daily) | Obesity | Daily pill | 35% | 24% | 25% | 24% | 69% vs. 37% | 6% vs. 0.7% |
| Saxenda (liraglutide 3 mg daily) | Obesity | Daily shot | 39% | 16% | 21% | 19% | 68% vs. 39% | 6.2% vs. 0.8% |
| Zepbound (tirzepatide 15 mg weekly) | Obesity, sleep apnea | Weekly shot | 28% | 13% | 23% | 11% | 56% vs. 30% | 4.3% vs. 0.5% |
| Rybelsus (semaglutide 14 mg daily) | Type 2 diabetes | Daily pill | 20% | 8% | 10% | 5% | 41% vs. 21% | 8% vs. 1% |
| Ozempic tablets (semaglutide 4–9 mg daily) | Type 2 diabetes | Daily pill | Same label as Rybelsus; not mg-for-mg substitutable | — | — | — | — | — |
| Mounjaro (tirzepatide 15 mg weekly) | Type 2 diabetes | Weekly shot | 18% | 9% | 17% | 7% | 44% vs. 20% | 6.6% vs. 0.4% |
| Trulicity (dulaglutide 1.5 mg weekly) | Type 2 diabetes, CV risk | Weekly shot | 21% | 13% | 13% | 4% | 41% vs. 21% | 3.5% vs. 0.2% |
| Ozempic injection (semaglutide 1 mg weekly) | Type 2 diabetes, CV risk, kidney | Weekly shot | 20% | 9% | 9% | 3% | 36% vs. 15% | 3.8% vs. 0.4% |
| Victoza (liraglutide 1.8 mg daily) | Type 2 diabetes, CV risk | Daily shot | 20% | 9% | 12% | 5% | — | 4.3% vs. 0.5% |
Sources: each drug's current FDA prescribing information. Saxenda's all-cause adverse-reaction discontinuation was higher (9.8% vs. 4.3% placebo); the figure above is the GI-specific subset. Green rows = weight-loss-approved drugs. Full source links are in the methodology section.
How to Read This GLP-1 Side Effects Comparison Chart
The FDA prescribing information for every one of these drugs includes a sentence that says, more or less: “Adverse reaction rates from clinical trials cannot be directly compared to rates in other trials.” That's because trials are run under different conditions — different doses, different durations, different populations, different reporting rules.
So when you see Wegovy's 44% nausea rate vs. Zepbound's 28% nausea rate, the right read is: “Both are high. Wegovy was studied at a dose that pushed nausea higher in its own trial population.” When the actual head-to-head trial exists — and for Wegovy vs. Zepbound, it does — we cover it below.
What the chart IS good for
- Spotting which drugs have the highest digestive burden as a class
- Comparing the same drug at different doses
- Comparing weight-loss-dose drugs to each other
- Comparing diabetes-dose drugs to each other
- Bringing a specific question to your prescriber
What the chart is NOT good for
- Picking the “safest” drug without your medical history
- Predicting how you will feel after the first dose
- Comparing weight-loss doses to diabetes doses directly
- Decisions about pancreatitis, gallbladder, kidney issues, or thyroid history
Which GLP-1 Has the Most Side Effects?
The pattern is clear: weight-loss-dose drugs cause more digestive side effects than diabetes-dose drugs of the same active ingredient. Wegovy is semaglutide at 2.4 mg per week. Ozempic injection is the same active ingredient at 1 mg or 2 mg per week. Wegovy's nausea rate is 44%. Ozempic's is 20%. Same molecule. Different dose.
The honest tolerability metric: GI-driven discontinuation (sorted lowest to highest)
| Drug | GI-driven discontinuation | Category |
|---|---|---|
| Wegovy HD 7.2 mg | 3% | Obesity |
| Trulicity 1.5 mg | 3.5% | Diabetes |
| Ozempic injection 1 mg | 3.8% | Diabetes |
| Wegovy injection 2.4 mg | 4.3% | Obesity |
| Zepbound 15 mg | 4.3% | Obesity |
| Victoza 1.8 mg | 4.3% | Diabetes |
| Foundayo 17.2 mg | 6% | Obesity |
| Saxenda 3 mg | 6.2% | Obesity |
| Mounjaro 15 mg | 6.6% | Diabetes |
| Rybelsus 14 mg | 8% | Diabetes |
Rybelsus surprises a lot of people. It's a daily oral pill with strict empty-stomach rules. Per the FDA label, more patients quit Rybelsus over GI side effects than any other FDA-approved GLP-1 in this chart.
Which GLP-1 Has the Fewest Side Effects?
3% GI discontinuation
Approved for obesity. Trial population had already cleared dose escalation, so this reflects long-term tolerability rather than new-dose peak effects.
3.5% GI discontinuation, 21% nausea
FDA-approved for type 2 diabetes, not obesity. Weekly injection.
3.8% GI discontinuation, 20% nausea
FDA-approved for type 2 diabetes, not obesity. Weekly injection.
GLP-1 Side Effects by Symptom
GLP-1 Nausea Comparison
Nausea is on the FDA label of every GLP-1 receptor agonist. It usually peaks during the first few weeks and again during each dose increase, then settles.
Highest nausea rates (label data)
- Wegovy injection 2.4 mg: 44%
- Wegovy HD 7.2 mg: 39%
- Saxenda 3 mg: 39%
- Foundayo 17.2 mg: 35%
- Zepbound 15 mg: 28%
Lowest nausea rates (label data)
- Mounjaro 5 mg (low diabetes dose): 12%
- Mounjaro 15 mg: 18%
- Ozempic 1 mg: 20%
- Trulicity 1.5 mg: 21%
- Rybelsus 14 mg: 20%
- Victoza 1.8 mg: 20%
If nausea is your main concern, diabetes-dose drugs and tirzepatide at lower doses are the gentler options in label terms.
GLP-1 Vomiting Comparison
Vomiting matters because it can cause dehydration, and dehydration can cause kidney injury. The FDA has noted postmarketing reports of acute kidney injury in GLP-1 patients, mostly in people who got dehydrated from severe nausea or vomiting.
Highest vomiting rates
- Wegovy injection: 24–25%
- Foundayo 17.2 mg: 24%
- Wegovy HD: 22%
- Saxenda: 16%
- Zepbound 15 mg: 13%
- Trulicity 1.5 mg: 13%
Lowest vomiting rates
- Mounjaro 5 mg: ~5%
- Rybelsus 14 mg: 8%
- Ozempic 1 mg: 9%
- Victoza 1.8 mg: 9%
- Mounjaro 15 mg: 9%
GLP-1 Diarrhea Comparison
Diarrhea is not a simple tirzepatide-vs.-semaglutide rule. In diabetes-dose label data, Mounjaro 15 mg reports more diarrhea than Ozempic 1 mg (17% vs. 9%). In weight-loss-dose label data, Wegovy 2.4 mg reports more diarrhea than Zepbound 15 mg (30% vs. 23%). And in the actual SURMOUNT-5 head-to-head trial, diarrhea was almost identical between the two: 23.5% with tirzepatide vs. 23.4% with semaglutide.
Highest diarrhea rates
- Wegovy injection: 30%
- Foundayo 17.2 mg: 25%
- Zepbound 15 mg: 23%
- Saxenda: 21%
- Mounjaro 15 mg: 17%
Lowest diarrhea rates
- Ozempic 1 mg: 9%
- Rybelsus 14 mg: 10%
- Victoza 1.8 mg: 12%
GLP-1 Constipation Comparison
Constipation matters more than people expect. A lot of people can push through mild nausea but bail on a drug after two weeks of painful constipation. It can also signal severe gastroparesis in rare cases.
Highest constipation rates
- Wegovy injection: 24%
- Foundayo 17.2 mg: 24%
- Wegovy HD: 20%
- Saxenda: 19%
- Zepbound 15 mg: 11%
Lowest constipation rates
- Ozempic 1 mg: 3%
- Trulicity 1.5 mg: 4%
- Rybelsus 14 mg: 5%
- Victoza 1.8 mg: 5%
If constipation is your concern, ask your prescriber for a prevention plan before your first dose. Hydration, fiber, movement, and stool softeners may be part of it, but the safest plan depends on your kidneys, other medications, and baseline bowel habits.
Reflux, Burping, Bloating, and “Sulfur Burps”
Reddit and patient forums talk about “sulfur burps” — eggy-smelling burps that come from delayed gastric emptying. The FDA labels don't use that term. They use clinical names:
- Dyspepsia (indigestion):Listed on Ozempic, Wegovy, Mounjaro, Zepbound, Foundayo, Saxenda, Rybelsus.
- GERD (acid reflux):Listed on Wegovy, Zepbound, Foundayo.
- Eructation (burping):Listed on most GLP-1 labels at 2–8%.
- Flatulence (gas):Listed on most labels at 1–4%.
- Abdominal distension (bloating):Listed on Wegovy, Foundayo, Rybelsus.
These are dose-related. They tend to peak in the first few weeks of a new dose and improve. Eating smaller meals, avoiding heavy fatty foods, and slowing down at the table all help more than antacids do in most cases.
Hair Loss, Fatigue, Headache, and Injection Reactions
- Hair loss:Label-tabled for Zepbound (5%), Foundayo (5%), and Wegovy HD (6%) in weight-loss trials. Most cases are linked to rapid weight loss (telogen effluvium), not the drug itself. Hair usually grows back after weight stabilizes.
- Headache:On most labels — 5–14% depending on drug and dose.
- Fatigue:On Wegovy, Wegovy HD, Zepbound, Saxenda, and Foundayo labels — 5–11%.
- Injection site reactions:Redness, itching, swelling at the shot site — on every injection label at 1–14%. Not applicable to oral pills.
Wegovy vs. Zepbound Side Effects (Including SURMOUNT-5 Head-to-Head)
Separate FDA-label comparison: Wegovy 2.4 mg vs. Zepbound 15 mg
| Side effect | Wegovy 2.4 mg (semaglutide) | Zepbound 15 mg (tirzepatide) |
|---|---|---|
| Nausea | 44% | 28% |
| Vomiting | 24–25% | 13% |
| Diarrhea | 30% | 23% |
| Constipation | 24% | 11% |
| Abdominal pain | 20% | 10% |
| Hair loss | Not separately tabled at ≥5% | 5% |
| Overall GI rate | 73% | 56% |
| GI discontinuation | 4.3% | 4.3% |
Actual SURMOUNT-5 head-to-head trial: tirzepatide vs. semaglutide
| Side effect | Tirzepatide (Zepbound) | Semaglutide (Wegovy) |
|---|---|---|
| Nausea | 43.6% | 44.4% |
| Constipation | 27.0% | 28.5% |
| Diarrhea | 23.5% | 23.4% |
| Vomiting | 15.0% | 21.3% |
| GERD | 6.1% | 10.6% |
| Dyspepsia | 5.9% | 7.4% |
| Injection-site reactions | 8.6% | 0.3% |
| Alopecia (hair loss) | 8.3% | 6.1% |
| GI-driven discontinuation | 2.7% | 5.6% |
Amber rows = statistically meaningful differences between the two drugs.
Two things to notice. First, the separate-label numbers make Wegovy look harder on the stomach than Zepbound across the board. The head-to-head numbers tell a more specific story: nausea and diarrhea are nearly identical. The real gaps are vomiting (semaglutide higher), GI-driven discontinuation (semaglutide higher), and injection-site reactions (tirzepatide much higher).
Practical read: If you've struggled with vomiting on past medications, Zepbound has the lower vomiting rate in the head-to-head trial. If you've struggled with skin irritation at injection sites, Wegovy had almost no injection-site reactions in the same trial.
Ozempic vs. Mounjaro Side Effects
| Side effect | Ozempic 1 mg (semaglutide) | Mounjaro 15 mg (tirzepatide) |
|---|---|---|
| Nausea | 20% | 18% |
| Vomiting | 9% | 9% |
| Diarrhea | 9% | 17% |
| Constipation | 3% | 7% |
| Abdominal pain | 6% | 5% |
| Overall GI rate | 36% | 44% |
| GI discontinuation | 3.8% | 6.6% |
Mounjaro's nausea rate is 12% at the lowest 5 mg dose and rises to 18% at 15 mg. Ozempic's nausea rate is 16% at 0.5 mg and 20% at 1 mg, then 21% at 2 mg. Both drugs are dose-dependent. Starting low and titrating slowly cuts the side effect peak in either case.
Are Oral GLP-1 Pills Easier on the Stomach Than Injections?
Rybelsus
Oral semaglutide, FDA-approved 2019, for type 2 diabetes. 41% overall GI rate; 8% GI-driven discontinuation (highest in the chart).
Empty stomach, morning, ≤4 oz water, wait 30 min before food/drink/other meds.
Ozempic tablets
Same label as Rybelsus, but not mg-for-mg substitutable. Rybelsus 7 mg → Ozempic tablets 4 mg; Rybelsus 14 mg → Ozempic tablets 9 mg.
Same empty-stomach rules as Rybelsus.
Wegovy tablets
Oral semaglutide 25 mg, FDA-approved December 2025, for weight loss and CV risk. GI events similar in type and frequency to Wegovy injection per label; some data suggest slightly fewer severe GI events (~2% vs. ~4%).
Empty stomach, morning, ≤4 oz water, wait 30 min.
Foundayo
Oral orforglipron, FDA-approved April 1, 2026, for weight loss. 69% overall GI rate; 6% GI-driven discontinuation. The only oral GLP-1 without strict timing rules.
Any time of day, with or without food or water. The only oral GLP-1 with this flexibility.
Why the pill isn't gentler: Daily dosing means daily peak exposure to the active drug. Weekly injections have a longer half-life and a smoother drug level. Some people tolerate the smooth weekly curve better. Others prefer the daily routine.
The bigger point: If you're choosing between a pill and a shot, the deciding factor is usually format preference (do you hate needles? are you bad at remembering daily medications?) — not stomach tolerability.
Serious GLP-1 Side Effects That Need Same-Day Medical Care
Acute pancreatitis
- What to feel for: Severe upper abdominal pain that often radiates straight through to your back. Usually steady and worsening, not crampy. Often with nausea or vomiting.
- Frequency: Rare. Wegovy adult trials reported 0.2 cases per 100 patient-years vs. <0.1 on placebo. Foundayo’s label reported 0.14 cases per 100 patient-years vs. 0.04 on placebo.
- What to do: Call your prescriber that day. Go to the ER if the pain is severe, persistent, or you can’t reach them. Labels say GLP-1 treatment should be discontinued if pancreatitis is suspected.
Acute gallbladder disease (cholelithiasis or cholecystitis)
- What to feel for: Severe pain in the upper right side of your abdomen, often after a fatty meal. Yellowing of the skin or eyes (jaundice). Fever. Persistent vomiting.
- Frequency: On Wegovy adult trials, gallstones in 1.6% vs. 0.7% on placebo. Cholecystitis in 0.6% vs. 0.2%. Higher in adolescent trials — 3.8% on Wegovy vs. 0%.
- What to do: Don’t wait. Gallbladder pain is hard to ignore. Get evaluated the same day.
Acute kidney injury from dehydration
- What to feel for: Lightheadedness when standing, dark urine, urinating less often, fatigue beyond what the drug normally causes.
- Frequency: Postmarketing reports only — the FDA doesn’t estimate a rate. Most cases happen during dose escalation in patients who had vomiting or diarrhea.
- What to do: Follow your prescriber’s hydration plan during dose escalation. If you can’t keep fluids down for more than 24 hours, get same-day medical advice.
Severe gastroparesis or possible bowel obstruction
- What to feel for: Persistent vomiting of food eaten hours earlier. Severe bloating. Inability to pass stool or gas. Severe abdominal pain that gets worse.
- Frequency: Postmarketing reports; frequency not estimated. Wegovy and Mounjaro labels say the drugs are “not recommended” for patients with severe gastroparesis already.
- What to do: Stop the drug and get evaluated. This is not something to push through.
Severe allergic reaction (anaphylaxis or angioedema)
- What to feel for: Swelling of the face, lips, tongue, or throat. Hives all over the body. Trouble breathing. Fainting.
- What to do: ER, immediately. Do not take another dose unless a prescriber clears it.
Diabetic retinopathy complications
- What to feel for: New blurriness, floaters, or vision changes.
- Frequency: In a 2-year Ozempic cardiovascular trial in high-risk diabetic patients, 3% on Ozempic had retinopathy complications vs. 1.8% on placebo.
- What to do: If you have retinopathy, see your eye doctor before starting a GLP-1 and again a few months in.
Thyroid C-cell tumor warning (boxed warning on all GLP-1s)
- Every GLP-1 in this chart carries a thyroid C-cell tumor boxed warning, based on rodent studies.
- The rule: GLP-1s are contraindicated if you or a close family member has medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).
- For everyone else: routine calcitonin or thyroid ultrasound monitoring is of uncertain value and is not generally recommended per the labels.
Anesthesia and surgery
- GLP-1s slow stomach emptying. Food may still be in your stomach during anesthesia even after the normal fasting window, raising the risk of pulmonary aspiration.
- What to do: Tell every surgeon, dentist, and anesthesiologist that you’re on a GLP-1 before any procedure. Current multi-society guidance says most patients can continue GLP-1 drugs before elective surgery, but high-risk patients may need plan modifications.
What the FDA Did in January 2026 That Most Pages Still Get Wrong
In July 2023, the FDA started investigating reports of suicidal thoughts in patients taking GLP-1 drugs for weight loss. In January 2024, the FDA issued a preliminary update saying it had not found evidence of a link but couldn't rule out a small risk because individual trials had too few cases to be definitive.
Then the FDA did the bigger work. They built a meta-analysis combining 91 placebo-controlled trials. They pulled in 107,910 patients — 60,338 on a GLP-1 and 47,572 on placebo. They also ran a separate analysis of 2.2 million healthcare-claims records comparing GLP-1 users to people on a different diabetes medication class (SGLT2 inhibitors).
The verdict, issued January 13, 2026: no increased risk of suicidal ideation or behavior in those analyses. No increased risk of anxiety, depression, irritability, or psychosis either. The FDA requested label removal of the warning from Saxenda, Wegovy, and Zepbound — the three GLP-1s that had carried the warning. Ozempic, Mounjaro, Trulicity, Victoza, and Rybelsus never carried that warning because it had been added only to weight-loss indications.
Why most pages have this wrong: it takes drugmakers many months to print updated labels. Pages written before January 13, 2026 — which is the vast majority of GLP-1 side effects content on the web — still describe the warning as active.
What this means for you
Mood changes still matter as a general health issue. If you experience new depression, mood changes, or thoughts of self-harm while on any medication, tell your doctor.
If you are thinking about harming yourself or you may act on suicidal thoughts, call or text 988 in the U.S. or use local emergency services now.
The FDA's finding is that the available analyses did not show an increased risk — not that mental health is irrelevant. Continue any antidepressant or mental health treatment as prescribed.
How Long Do GLP-1 Side Effects Last?
Weeks 1–4 (starting dose)
Nausea is often worst. Most people feel less hungry and may have mild stomach upset. About 30% of people on a weight-loss-dose GLP-1 will have at least one episode of nausea.
Weeks 5–12 (dose increases)
Each step up can trigger a new symptom peak. Symptoms usually settle within 1–2 weeks at each new dose for most people.
Months 4–6 (maintenance dose reached)
Most people stabilize. The drug is doing its job and the side effects have dropped to a much lower baseline.
Beyond 6 months
Most patients who stuck with it through the early window report tolerable side effects long-term.
About 4–8% of patients on each weight-loss GLP-1 quit during this window because the side effects don't fade fast enough. The FDA labels are explicit that if you don't tolerate a dose during escalation, your prescriber can delay the next increase by 4 weeks. Some labels allow staying at the lower maintenance dose long-term.
Practical rule: If you're two weeks into a new dose and the side effects are getting worse instead of better, call your prescriber. Don't push through. There's nothing virtuous about white-knuckling a dose your body is rejecting.
Who's More Likely to Struggle with GLP-1 Side Effects?
History of severe GI motility issues
Chronic severe constipation, severe gastroparesis, prior bowel obstruction. The labels say GLP-1s are “not recommended” for severe gastroparesis specifically.
Taking insulin or a sulfonylurea for diabetes
GLP-1s by themselves rarely cause low blood sugar (hypoglycemia), but added to insulin or a sulfonylurea, the combined risk goes up. Your prescriber may reduce insulin doses when starting a GLP-1.
Prior gallbladder disease or pancreatitis
Not an absolute contraindication, but the risk math changes. Discuss with your prescriber.
Kidney disease
Vomiting and diarrhea hit harder when your kidneys can’t recover as easily. Ask for a sick-day plan.
Diabetic retinopathy
Needs an eye exam before starting and follow-up during the rapid-improvement window.
Upcoming surgery or anesthesia
Tell every member of your medical team. Current multi-society guidance is more individualized than older “skip the dose” advice.
Personal or family history of MTC or MEN 2
A contraindication. GLP-1s are not for you.
How to Use This Chart Before Your Next Doctor Appointment
If you haven’t started yet
- “Which side effect am I most likely to have, and how slowly can we titrate to minimize it?”
- “What symptoms should make me call you the same day?”
- “What symptoms require urgent care or the ER?”
- “If I have a history of [gallbladder issues / kidney issues / GI motility / retinopathy], how does that change the plan?”
- “If side effects don’t improve, do we pause the dose, switch drugs, or stop entirely?”
Before increasing a dose
- “Are my current side effects acceptable to increase the dose, or should we hold at this dose for another month?”
- “What constipation prevention plan should I have in place before the next step?”
- “Are there any signs we should switch drugs instead of going up?”
Before switching from one GLP-1 to another
- “Why are we switching — side effects, cost, insurance, or effect?”
- “Do I need a washout period or can I start the new drug right away?”
- “Do I restart at the lowest dose or pick up at an equivalent dose?”
- “Will the new drug have a different side effect pattern?”
What This GLP-1 Side Effects Comparison Chart Does NOT Prove
Quick answer: This chart shows patterns in label-reported side effects. It does not prove one drug is universally safer or better-tolerated than another, because trial designs, doses, patient populations, and reporting rules differ. Where an actual head-to-head trial exists (Wegovy vs. Zepbound in SURMOUNT-5), we cover it separately. Use the chart to inform a conversation, not to make a final decision.
- Not a head-to-head safety ranking for most drug pairs. Each drug’s percentages come from its own trial unless we explicitly cite a head-to-head trial.
- Not medical advice. We compare labels. We don’t write prescriptions.
- Not coverage of compounded GLP-1 drugs. Compounded semaglutide and tirzepatide have different concentrations, additives, and quality control. These percentages apply only to FDA-approved branded products.
- Not a ranking of cost, effectiveness, insurance coverage, or weight-loss outcome. This page is about side effects only.
Older GLP-1 Drugs That Are No Longer Broadly Available
| Drug | Active ingredient | Status |
|---|---|---|
| Byetta | Exenatide (twice daily) | Discontinued in the U.S. |
| Bydureon / Bydureon BCise | Exenatide extended-release (weekly) | Discontinued by AstraZeneca in late 2024 |
| Adlyxin | Lixisenatide (daily) | No longer available in the U.S. |
If a website still recommends Bydureon BCise as a current treatment option, you can safely conclude the page hasn't been updated in a while.
Frequently Asked Questions
- Which GLP-1 has the most nausea?
- In FDA label data, Wegovy injection (semaglutide 2.4 mg) has the highest nausea rate at 44%, followed by Wegovy HD 7.2 mg (39%), Saxenda (39%), Foundayo at the maintenance dose (35%), and Zepbound (28%).
- Which GLP-1 causes the worst constipation?
- Wegovy injection and Foundayo both report 24% constipation in their trials. Wegovy HD reports 20%, Saxenda reports 19%, and Zepbound reports 11%. Diabetes-dose drugs (Ozempic injection, Trulicity, Rybelsus) report 3–5% constipation.
- Which GLP-1 causes the most diarrhea?
- Wegovy injection reports the highest diarrhea rate at 30%, followed by Foundayo (25%), Zepbound (23%), Saxenda (21%), and Mounjaro (17%). In the SURMOUNT-5 head-to-head trial, tirzepatide and semaglutide had nearly identical diarrhea rates (23.5% vs. 23.4%).
- Which GLP-1 has the highest discontinuation rate from side effects?
- Rybelsus 14 mg has an 8% GI-related discontinuation rate — the highest among the FDA-approved GLP-1s we tracked. Mounjaro 15 mg shows 6.6%, Saxenda shows 6.2%, and Foundayo at 17.2 mg shows 6%. Saxenda’s all-cause adverse-reaction discontinuation was 9.8%, but most of that was GI.
- Are Wegovy side effects worse than Zepbound?
- In each drug’s separate clinical trial, Wegovy reports higher rates of nausea, vomiting, diarrhea, constipation, and overall GI events than Zepbound. In the actual SURMOUNT-5 head-to-head trial, nausea and diarrhea were nearly identical between the two, but vomiting and GI-driven discontinuation were higher with semaglutide, and injection-site reactions were higher with tirzepatide.
- Are Mounjaro side effects worse than Ozempic?
- For type 2 diabetes at maintenance doses, Mounjaro (tirzepatide 15 mg) shows higher diarrhea (17% vs. 9%), higher constipation (7% vs. 3%), a higher overall GI rate (44% vs. 36%), and a higher GI discontinuation rate (6.6% vs. 3.8%) than Ozempic (semaglutide 1 mg). Nausea is similar (18% vs. 20%).
- Do GLP-1 side effects go away?
- Most digestive side effects are most common during dose escalation and tend to improve as the body adjusts to a stable dose. Several FDA labels state this directly. Severe or worsening symptoms should be discussed with your prescriber rather than pushed through.
- Should I stop my GLP-1 if I’m having side effects?
- Do not stop, restart, or change your dose without talking to your prescriber, unless you have specific instructions to do so. Severe symptoms — persistent vomiting, severe abdominal pain, signs of dehydration, allergic reaction symptoms, or signs of hypoglycemia — require same-day medical advice.
- Are GLP-1 pills easier on the stomach than injections?
- No, not in the data. Rybelsus, Ozempic tablets, Wegovy tablets, and Foundayo all show meaningful GI side effect rates similar to or higher than comparable injections. Pills offer dosing convenience, not gentler tolerability. Rybelsus has the highest GI-driven discontinuation rate (8%) of any FDA-approved GLP-1.
- Can GLP-1 drugs cause pancreatitis?
- Yes, but rarely. Wegovy adult trials reported 0.2 cases per 100 patient-years vs. less than 0.1 on placebo. Foundayo’s label reported adjudicated acute pancreatitis at 0.14 cases per 100 patient-years on treatment vs. 0.04 on placebo. The symptom to watch is severe upper abdominal pain that radiates to the back, often with nausea or vomiting. It needs same-day medical evaluation.
- Can GLP-1 drugs cause gallbladder problems?
- Yes. On Wegovy adult trials, gallstones occurred in 1.6% vs. 0.7% on placebo, and inflammation (cholecystitis) in 0.6% vs. 0.2%. Rapid weight loss is the underlying driver. Severe right-upper abdominal pain, yellowing of the eyes or skin, or persistent vomiting warrants prompt evaluation.
- Did the FDA remove the suicide warning from GLP-1 drugs?
- Yes. On January 13, 2026, the FDA issued a Drug Safety Communication requesting removal of the suicidal ideation and behavior warning from Saxenda, Wegovy, and Zepbound labels. A meta-analysis of 91 trials and 107,910 patients did not show an increased risk. Drugmakers are phasing out the warning. Pages and product inserts written before January 13, 2026 may still display it.
- Can GLP-1 drugs cause hair loss?
- Hair loss is label-tabled for Zepbound (5%), Foundayo (5%), and Wegovy HD (6%) in their weight-loss trials. Most cases are linked to rapid weight loss (telogen effluvium) rather than a direct drug effect. Hair usually regrows after weight stabilizes.
- What are sulfur burps and which GLP-1 causes them?
- “Sulfur burps” is a patient term for eggy-smelling burps from slowed stomach emptying. The FDA labels list this under “eructation,” which appears on most GLP-1 labels at 2–8%. It is not specific to one drug and tends to improve as the body adjusts.
- Is Wegovy HD different from regular Wegovy for side effects?
- Wegovy HD is a higher-dose version of Wegovy (semaglutide 7.2 mg weekly vs. 2.4 mg), FDA-approved March 19, 2026. The label-reported nausea rate is 39% (vs. 44% on standard Wegovy), vomiting 22% (vs. 24–25%), constipation 20% (vs. 24%), and GI-driven discontinuation 3% (vs. 4.3%). The Wegovy HD trial population had already cleared dose escalation before the comparison period, which is part of why the percentages look more favorable.
Sources and Methodology
We built this comparison by pulling current FDA or manufacturer prescribing information for every GLP-1 receptor agonist currently approved for use in the United States. We did not paraphrase from secondary articles. We read the labels.
Primary sources for side-effect percentages
- Wegovy and Wegovy HD (semaglutide injection) prescribing information, revised May 2026 — novo-pi.com/wegovy.pdf and FDA accessdata
- Rybelsus and Ozempic tablets (oral semaglutide) prescribing information, 2026 — FDA accessdata, label 213051s030
- Ozempic (semaglutide injection) prescribing information, 2025 — FDA accessdata, label 209637s035, s037
- Mounjaro (tirzepatide) prescribing information, 2025 — FDA accessdata, label 215866s039
- Zepbound (tirzepatide) prescribing information, 2026 — FDA accessdata, label 217806s002
- Trulicity (dulaglutide) prescribing information, revised March 2026 — FDA accessdata, label 125469s065
- Saxenda (liraglutide) prescribing information, 2026 — FDA accessdata, label 206321s025
- Victoza (liraglutide) prescribing information, 2025 — FDA accessdata
- Foundayo (orforglipron) prescribing information, April 2026 — FDA accessdata, label 220934Orig1s000
Head-to-head trial data
- SURMOUNT-5: tirzepatide vs. semaglutide for weight reduction in adults with obesity (2025) — published trial data, Cornell eCommons archive
Regulatory updates
- FDA Drug Safety Communication, January 13, 2026 — “FDA Requests Removal of Suicidal Behavior and Ideation Warning from GLP-1 RA Medications” — fda.gov/drugs/drug-safety-communications
- FDA approval announcement, March 19, 2026 — Wegovy HD 7.2 mg
- ASA/multi-society guidance on GLP-1 use before elective surgery (most recent update referenced)
Supporting comparative evidence
Xie et al. (2025). Comparative gastrointestinal adverse effects of GLP-1 receptor agonists and multi-target analogs in type 2 diabetes: a Bayesian network meta-analysis. Frontiers in Pharmacology. 48 randomized controlled trials, 27,729 participants. PMC12491879.
About This Page
What we are: The RX Index is a pricing and product intelligence resource for the GLP-1 telehealth market. We earn affiliate revenue when readers choose a provider through our site. Our editorial work compares FDA prescribing information, current pricing, regulatory updates, and clinical-trial data. We do not write medical advice. Affiliate compensation does not influence which drugs appear in our comparison charts or which percentages we report — those come from the labels.
Source-checked by: The RX Index editorial team. No external medical review is claimed.
Written by: The RX Index editorial team
Published: · Last reviewed:
Conflicts of interest: Affiliate links appear on other pages of this site. This comparison page does not contain affiliate links. Drug selection and percentages are determined by which drugs are currently FDA-approved in the U.S. and what their labels say.