GLP-1 side effects across the labels
In short
Stomach and gut problems lead the common side effects on all four labels. Nausea is the most common in each label's main table: 15.8 to 20.3% of people on Ozempic, 44% on the Wegovy shot, 12 to 18% on Mounjaro and 25 to 29% on Zepbound. On placebo it was 4 to 16%.1‑4 All four labels also carry a boxed warning about thyroid C-cell tumors seen in rodents.
If you have a side effect, or one that worries you, talk to your prescriber or pharmacist. This page shows what the labels list. It can't tell you what to do.
What are the common side effects of GLP-1 shots?
Each cell is the share of people in the label's trials who reported it, on the drug vs on placebo. Where a label tests several doses, the range covers all of them.
| Side effect | Ozempic | Wegovy shot | Mounjaro | Zepbound |
|---|---|---|---|---|
| Nausea | 15.8 to 20.3% (placebo 6.1%) | 44% (placebo 16%) | 12 to 18% (placebo 4%) | 25 to 29% (placebo 8%) |
| Diarrhea | 8.5 to 8.8% (placebo 1.9%) | 30% (placebo 16%) | 12 to 17% (placebo 9%) | 19 to 23% (placebo 8%) |
| Vomiting | 5 to 9.2% (placebo 2.3%) | 24% (placebo 6%) | 5 to 9% (placebo 2%) | 8 to 13% (placebo 2%) |
| Constipation | 3.1 to 5% (placebo 1.5%) | 24% (placebo 11%) | 6 to 7% (placebo 1%) | 11 to 17% (placebo 5%) |
| Stomach pain | 5.7 to 7.3% (placebo 4.6%) | 20% (placebo 10%) | 5 to 6% (placebo 4%) | 9 to 10% (placebo 5%) |
| Indigestion | – | 9% (placebo 3%) | 5 to 8% (placebo 3%) | 9 to 10% (placebo 4%) |
| Lower appetite | – | – | 5 to 11% (placebo 1%) | – |
| Headache | – | 14% (placebo 10%) | – | – |
| Tiredness | – | 11% (placebo 5%) | – | 5 to 7% (placebo 3%) |
| Dizziness | – | 8% (placebo 4%) | – | 4 to 5% (placebo 2%) |
| Burping | – | 7% (placebo under 1%) | – | 4 to 5% (placebo 1%) |
| Bloating | – | 7% (placebo 5%) | – | 3 to 4% (placebo 2%) |
| Gas | – | 6% (placebo 4%) | – | 3 to 4% (placebo 2%) |
| Acid reflux | – | 5% (placebo 3%) | – | 4 to 5% (placebo 2%) |
| Hair loss | – | 3% (placebo 1%) | – | 4 to 5% (placebo 1%) |
| Injection site reactions | – | – | – | 6 to 8% (placebo 2%) |
| Allergic reactions | – | – | – | 5% (placebo 3%) |
A dash means the side effect isn't in that label's main table. The tables use different cutoffs: Ozempic and Mounjaro list side effects in at least 5% of people, Wegovy and Zepbound in at least 2% and more often than placebo. Each label lists a few more rows than shown here.
Can I compare the four columns?
Not head to head. Each column comes from different trials in different people. The Ozempic and Mounjaro tables are from adults with type 2 diabetes. The Wegovy table is from 3 trials in 2,116 adults with obesity or overweight, lasting up to 68 weeks (Wegovy label). The Zepbound table is from 2 trials in adults with obesity or overweight (Zepbound label).
Do GLP-1s cause hair loss?
Two labels list it. Hair loss was reported by 3% of adults on the Wegovy shot vs 1% on placebo (Wegovy label), and by 4 to 5% on Zepbound vs 1% on placebo (Zepbound label). The Ozempic and Mounjaro main tables don't list it.
How many people stop because of side effects?
In the three Wegovy weight trials, 6.8% of adults on Wegovy and 3.2% on placebo stopped for good because of side effects. Nausea, vomiting and diarrhea were the most common reasons (Wegovy label).
What serious side effects do the labels warn about?
All four labels have a boxed warning: "Risk of thyroid C-cell tumors." The Zepbound label says "it is unknown whether ZEPBOUND causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans" (Zepbound label). All four say not to use them with a personal or family history of medullary thyroid cancer or MEN 2.
Section 5 (Warnings and Precautions) of all four labels also covers:
- Pancreatitis
- Gallbladder disease
- Kidney injury from losing fluids
- Severe stomach and gut reactions
- Serious allergic reactions
- Low blood sugar, including when used with insulin or drugs that make the body release insulin
- Diabetic eye problems in people with type 2 diabetes
- Food or liquid getting into the lungs during anesthesia or deep sedation
Sources: Ozempic, Wegovy, Mounjaro and Zepbound labels. The Wegovy label also lists a faster heart rate.
Are the side effects the same for every GLP-1?
The labels list similar ones, because these medicines work in similar ways. Ozempic and Wegovy are semaglutide. Mounjaro and Zepbound are tirzepatide. Which brand is which is in Ozempic vs Wegovy vs Mounjaro vs Zepbound. Other GLP-1s have their own labels: liraglutide (Saxenda, Victoza), dulaglutide (Trulicity) and oral semaglutide (Rybelsus, Wegovy pill).
Compounded versions have no FDA label and no label table. FDA's reports on them are in compounded vs brand GLP-1.
Where do I report a side effect?
Tell your prescriber first. You can also report it to FDA through MedWatch.
Sources
- Ozempic (semaglutide) injection prescribing information, section 6.1, Table 1 DailyMed, checked Nov 6, 2026
- Wegovy (semaglutide) injection and tablets prescribing information, section 6.1, Table 3 DailyMed, checked Nov 6, 2026
- Mounjaro (tirzepatide) injection prescribing information, section 6.1, Table 1 DailyMed, checked Nov 6, 2026
- Zepbound (tirzepatide) injection prescribing information, section 6.1, Table 1 DailyMed, checked Nov 6, 2026
- MedWatch: FDA safety information and adverse event reporting program FDA.gov, checked Nov 6, 2026
PepBloom is for tracking and education. It isn't medical advice. Talk to your prescriber.
