Starting a GLP-1 medication like semaglutide (Ozempic, Wegovy) or tirzepatide (Mounjaro, Zepbound) can come with an adjustment period. Some people notice they feel more tired than usual, or a little light-headed. This guide covers how common that is, everyday factors that can play a part, and when it's time to call your doctor.
Important: this article is general information. It can't tell you what's causing your symptoms. If something feels wrong, speak to your prescriber.
How common are fatigue and dizziness on a GLP-1?
Both are listed in the official prescribing information:
| Side effect | Wegovy 2.4 mg | Placebo | Zepbound 15 mg | Placebo |
|---|---|---|---|---|
| Fatigue | 11% | 5% | 7% | 3% |
| Dizziness | 8% | 4% | 4% | 2% |
| Nausea | 44% | 16% | 28% | 8% |
| Diarrhea | 30% | 16% | 23% | 8% |
| Vomiting | 24% | 6% | 13% | 2% |
So most people do not report fatigue or dizziness, but a noticeable minority do, more often than on placebo.
Everyday factors that can play a part
Your doctor is the right person to work out the cause. These are common, everyday factors worth mentioning to them:
- Eating much less. Smaller meals mean less energy, and fewer of the vitamins and minerals food normally provides. See Eating less on a GLP-1? The vitamins worth paying attention to.
- Not drinking enough. A smaller appetite often means fewer drinks with meals. The Wegovy and Zepbound labels both warn that nausea, vomiting or diarrhea can lead to dehydration.
- Stomach side effects. Nausea, vomiting and diarrhea are the most common side effects and can leave you feeling drained.
- Low blood sugar in some people with type 2 diabetes, especially if they also take insulin or a sulfonylurea. In Wegovy's trials, 6% of people with type 2 diabetes not on insulin had low blood sugar, versus 2% on placebo.
- Dose changes. Side effects are often more noticeable when the dose is increased.
Simple habits that may help you feel steadier
- Drink steadily through the day. Small sips often are easier than large amounts. Our guide How much water should you drink on semaglutide or tirzepatide? has practical targets.
- Don't skip meals entirely. Even small, protein-rich meals help.
- Stand up slowly, especially first thing in the morning.
- Keep moving gently. A short walk or light strength work supports energy and muscle.
- Track how you feel after each dose change, and share it at your next appointment.
When to call your doctor
Contact your doctor or prescriber if you have:
- Dizziness that doesn't go away, or fainting
- Vomiting or diarrhea that won't stop, or you can't keep fluids down
- Very little urine, or very dark urine
- Confusion, a racing heart, shakiness or sweating (possible low blood sugar if you have diabetes)
- Severe or ongoing stomach pain, sometimes spreading to the back
Call 911 or go to an emergency room if you have fainting with chest pain, trouble breathing, severe confusion or any symptom that feels like an emergency.
Where Zibby fits
Zibby Hydration is a zero-sugar daily drink mix made for women on a GLP-1 routine. It adds sodium, potassium, magnesium, vitamins C, B6 and B12 and 1,360 mg of creatine monohydrate to your water to help make a daily hydration habit easier.
Zibby does not treat or prevent side effects, and it is not a substitute for seeing your doctor. Learn more about Zibby →
Frequently asked questions
Is it normal to feel tired on Ozempic or Wegovy?
Fatigue is a listed side effect. In Wegovy's trials, 11% of people on the 2.4 mg dose reported fatigue versus 5% on placebo. If it is severe or doesn't improve, talk to your prescriber.
Can a GLP-1 make you dizzy?
Dizziness is also a listed side effect: 8% on Wegovy 2.4 mg and 4% on Zepbound 15 mg in trials. Ongoing dizziness or fainting needs a doctor's review.
Can dehydration cause dizziness on a GLP-1?
Dehydration can cause light-headedness, and the labels warn that stomach side effects can lead to dehydration. Your doctor can check what's causing your symptoms.
Sources
This article is for general education and is not medical advice. Talk to your healthcare provider about your own symptoms. *These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.