GLP-1 side effects: what the data actually shows
By Iacob Pastina, independent researcher & publisher · Updated September 8, 2026
Nausea, diarrhea, vomiting and constipation are common reported GLP-1 side effects. The percentages depend on the medicine, dose, formulation and study population. The table below identifies those groups; it cannot tell you which drug you will tolerate best or rank safety across separate trials.
Already dealing with symptoms? Use our practical guide to managing GLP-1 side effects for meal suggestions, questions for your prescriber and a symptom-note checklist. Severe or persistent symptoms need clinical assessment.
Educational information, not medical advice. This independently researched page has not been medically reviewed by a clinician. AI assistance was used to organize the label comparison.
Sources checked September 8, 2026:
- Wegovy prescribing information, section 6.1, Table 3: 2.4 mg weekly injection in adults with obesity or overweight, not the pill or higher-dose injection.
- Zepbound prescribing information, section 6.1, Table 1: 5, 10 and 15 mg weekly groups in pooled weight-management studies.
- Foundayo prescribing information, section 6.1, Table 1: 5.5, 9 and 17.2 mg equivalent daily doses in pooled weight-management trials; the label maps the investigational formulation to marketed doses.
- Rybelsus / Ozempic tablets prescribing information, section 6.1, Table 2: semaglutide 7 and 14 mg tablets in adults with type 2 diabetes. These are different doses and a different population from oral Wegovy weight-management trials.
How common are side effects in each label?
| Side Effect | Wegovy 2.4 mg injection | Zepbound injection | Foundayo tablets | Rybelsus 7 / 14 mg tablets |
|---|---|---|---|---|
| Nausea | 44% | 25-29% | 26-35% | 11-20% |
| Diarrhea | 30% | 19-23% | 21-25% | 9-10% |
| Vomiting | 24% | 8-13% | 13-24% | 6-8% |
| Constipation | 24% | 11-17% | 20-27% | 5-6% |
| Abdominal pain | 20% | 9-10% | 13-14% | 10-11% |
| Headache | 14% | Not in table | 8-9% | Not in table |
| Fatigue | 11% | 5-7% | 6-9% | Not in table |
| Hair loss | 3% | 4-5% | 4-5% | Not in table |
“Not in table” means the cited common-adverse-reaction table does not list that event; it does not mean the risk is zero. These studies had different participants, doses and placebo results. A lower percentage across columns is not evidence that one medicine is safer. Treatment-group totals also do not describe how one person's symptoms will change during dose escalation.
What can you do about symptoms?
The rate table explains what was reported in trials. For your own symptoms, start with severity, how long they have lasted and whether you can drink or eat. Our management guide helps you prepare that information for your prescriber without guessing at doses or supplements.
Get practical symptom-management help →Which side effects need urgent attention?
Know these warning signs before trying home remedies. They are not a diagnosis or an exhaustive list.
Pancreatitis
Severe abdominal pain that does not go away, sometimes reaching the back, needs immediate medical attention. The Wegovy and Zepbound Medication Guides instruct patients to stop treatment and contact a clinician for this symptom.
Gallbladder problems
Upper abdominal pain with fever, yellowing of the skin or eyes, or pale stools needs prompt clinical advice.
Dehydration and kidney injury
Persistent vomiting or diarrhea, difficulty drinking, or markedly reduced urination needs prompt assessment. Do not wait for a fixed 24-hour threshold.
Low blood sugar
Risk is especially relevant with insulin or sulfonylureas. Follow your clinician's low-blood-sugar plan. Severe confusion, fainting or a seizure requires emergency help.
Serious allergic reaction
Breathing difficulty or swelling of the face, lips, tongue or throat requires emergency help. Call 911 for breathing difficulty or collapse.
Thyroid C-cell tumor warning
The medicines listed here carry a boxed warning based on rodent findings with GLP-1 medicines; the human relevance is uncertain. They are contraindicated with a personal or family history of medullary thyroid carcinoma or MEN 2. Report a neck lump, persistent hoarseness or trouble swallowing.
Warning-sign sources: the Wegovy Medication Guide and Zepbound Medication Guide. Discuss your own medicine's instructions and medical history with your clinician.
What changed in the FDA mental-health warning?
On January 13, 2026, FDA requested removal of the suicidal-behavior and ideation warning from affected GLP-1 weight-management labels after its review found no increased risk. The older “under investigation” wording on this page was outdated. Read FDA's safety communication. New or worsening mental-health symptoms still deserve care; call or text 988 in the US for emotional distress or suicidal thoughts, and call 911 for immediate danger.