May 12, 2026
Common GLP-1 Side Effects and How to Track Them
Nausea, fatigue, and injection site reactions are common on GLP-1 therapy. A structured log helps you and your clinician manage them.
Starting a GLP-1 receptor agonist such as semaglutide or tirzepatide can be life-changing for glycaemic control and weight management. But side effects are common — especially during the titration phase.
Most common side effects
| Side effect | Typical timeline | Frequency |
|---|---|---|
| Nausea | First 4–8 weeks | Very common |
| Vomiting | First 4 weeks | Common |
| Diarrhoea | Variable | Common |
| Constipation | Ongoing | Common |
| Injection site reactions | Any time | Common |
| Fatigue | First 4 weeks | Moderately common |
Why tracking matters
A side-effect log turns subjective experience into objective data. When you walk into your doctor's appointment with a chart showing "nausea on days 3–5 after each dose" you enable a much more productive conversation about dose adjustment, antiemetic support, or switching therapies.
What to log
- Date and time of symptom onset
- Severity (mild / moderate / severe)
- Duration (hours)
- Timing relative to dose (same day, next day, etc.)
- Injection site (abdomen L, abdomen R, thigh L, etc.)
- Interventions (ginger tea, antiemetic, nothing)
Tips for reducing GI side effects
- Inject in the thigh rather than the abdomen — absorption is slightly slower and may reduce nausea.
- Take your dose right before bed so you sleep through the peak.
- Eat small, bland meals on dose day.
- Stay hydrated — dehydration amplifies fatigue and nausea.
- Titrate up slowly. Do not rush the dosing schedule.
TrackPep includes a dedicated side-effect logger that ties each symptom to a specific dose and compound, so you can spot patterns over weeks and months — not just guess.