Short answer: It can. In the clinical trials behind the prescribing information, fatigue (including weakness and low energy) was reported by 11% of adults on Wegovy 2.4 mg versus 5% on placebo, and by 5% to 7% on Zepbound versus 3% on placebo. Side effects are more likely in the first weeks and after a dose increase, and they tend to ease on a stable dose. Eating much less, losing fluids through nausea or diarrhea, and low blood sugar in people who also use insulin or a sulfonylurea can all play a part. If tiredness is strong or lasts, talk to your prescriber.
GLP-1 medications such as semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) are mostly known for nausea and other stomach side effects, but many people also notice they feel drained. Here is how common fatigue is, the likely reasons, what may help, and when to call your health care provider.
What you'll learn
- How often fatigue was reported on Wegovy, Zepbound and Ozempic
- When tiredness is most likely, and whether it goes away
- The most likely reasons GLP-1 medications can leave you tired
- What may help, including the role of coffee and other caffeine, and when to call your provider
How common is fatigue on GLP-1 medications?
The FDA-approved prescribing information lists fatigue among the side effects seen in clinical trials:
| Medication (trials) | Fatigue on the medication | Fatigue on placebo | Source |
|---|---|---|---|
| Wegovy (semaglutide 2.4 mg injection, weight management trials) | 11% | 5% | Wegovy prescribing information |
| Zepbound (tirzepatide 5, 10 or 15 mg, weight management trials) | 5%, 6% and 7% | 3% | Zepbound prescribing information |
| Ozempic (semaglutide, type 2 diabetes trials) | Listed among less common side effects (more than 0.4%) | Not reported in the table | Ozempic prescribing information |
In these tables, "fatigue" also includes related terms such as weakness (asthenia); for Zepbound it also covers lethargy and malaise (Zepbound prescribing information; Wegovy prescribing information). So most people on these medications did not report fatigue, but it was more common than on placebo.
When does it happen, and does it go away?
According to a joint advisory from four U.S. nutrition and obesity medicine organizations, side effects of GLP-1 medications are more likely in the first weeks of treatment and after each dose increase, and they tend to become less frequent and less severe once the dose is stable (Mozaffarian et al., 2025). That is a general pattern for side effects, most of which are digestive; how long tiredness lasts varies from person to person. Do not stop or change your medication on your own; talk to your provider first (MedlinePlus).
Why GLP-1 medications can make you tired
The prescribing information does not explain why fatigue happens, but several likely contributors are well described:
- Eating much less. People on GLP-1 medications for weight reduce their calorie intake by about 16% to 39%. At intakes below about 1,200 calories a day for women and 1,800 for men, it becomes hard to get enough vitamins and minerals, and fatigue beyond what you would expect can be a sign of a nutrient shortfall (Mozaffarian et al., 2025).
- Losing fluids. Nausea, vomiting and diarrhea can cause dehydration, and the prescribing information advises drinking fluids to lower that risk (Ozempic prescribing information; Zepbound prescribing information).
- Low blood sugar. If you also take insulin or a sulfonylurea, the risk of low blood sugar goes up. Its signs include weakness, drowsiness, shakiness, sweating, dizziness, hunger and confusion (Ozempic prescribing information).
- Something else entirely. Fatigue has many causes, including poor sleep, anemia or low iron, thyroid problems, depression, alcohol and other medicines (MedlinePlus). Starting a new medication does not rule these out.
What may help
These are general steps; check with your prescriber or a registered dietitian before making big changes.
- Eat small, regular meals. For people who stop eating because of nausea, the joint advisory suggests a small breakfast and then small meals every 3 to 4 hours, with enough fluids (Mozaffarian et al., 2025).
- Make the food you do eat count. Prioritize protein and nutrient-rich foods. The advisory notes that some people may need protein or vitamin and mineral supplements; ask your provider whether that applies to you (Mozaffarian et al., 2025).
- Drink enough fluids, especially if you have vomiting or diarrhea (Ozempic prescribing information).
- Protect your sleep, move regularly and manage stress, and avoid alcohol, which are general steps for reducing fatigue (MedlinePlus).
- Ask about your other medicines, especially insulin or a sulfonylurea; your prescriber may adjust them (Zepbound prescribing information).
Can you drink coffee on a GLP-1 medication?
The prescribing information for Zepbound, Wegovy, Ozempic and Mounjaro does not mention caffeine or coffee. That does not make caffeine a fix for tiredness: MedlinePlus notes that stimulants, including caffeine, are not effective treatments for fatigue and can make it worse when you stop (MedlinePlus). Caffeine also increases stomach acid, which can add to an upset stomach (MedlinePlus).
If you already drink coffee or tea and tolerate it, a moderate amount earlier in the day is a reasonable approach to discuss with your provider. For how drinks compare, see matcha vs coffee and how much caffeine is in matcha.
When to call your health care provider
Get medical help right away for confusion or dizziness, blurred vision, or little or no urine output (MedlinePlus). Call your provider if nausea, vomiting or diarrhea does not go away, if you have signs of low blood sugar, or if fatigue is severe, keeps getting worse or does not improve after a few weeks on a stable dose (Ozempic prescribing information; MedlinePlus).
Common myths (quick reality check)
Myth: Feeling tired means the medication is working. Reality: Fatigue is a side effect, not a sign of success. It is worth mentioning to your provider, especially if you are eating very little.
Myth: Coffee will fix GLP-1 fatigue. Reality: Caffeine is not an effective treatment for fatigue, and it can upset a sensitive stomach. Food, fluids and sleep come first.
Myth: Eating as little as possible is fine as long as you are losing weight. Reality: Very low intakes make it hard to get enough vitamins, minerals and protein, and unusual fatigue can be a sign of a shortfall.
Frequently asked questions (FAQ)
Does Ozempic make you tired?
It can. Fatigue is listed among the less common side effects of Ozempic. For Wegovy, which contains the same medicine (semaglutide) at a higher dose for weight management, fatigue was reported by 11% of adults versus 5% on placebo.
Does Zepbound or tirzepatide make you tired?
It can. In weight management trials, fatigue was reported by 5% to 7% of adults on Zepbound, depending on the dose, versus 3% on placebo.
Why am I so tired on semaglutide?
Common contributors include eating much less, losing fluids through nausea or diarrhea, and low blood sugar if you also take insulin or a sulfonylurea. Other causes such as poor sleep or low iron are possible too, so tell your provider.
How long does GLP-1 fatigue last?
Side effects are most likely in the first weeks and after dose increases, and they usually ease on a stable dose. If fatigue lasts or is severe, talk to your provider.
Can I drink coffee on Ozempic?
The prescribing information does not mention caffeine. Caffeine is not an effective treatment for fatigue and can upset the stomach, so if you drink it, keep it moderate and ask your provider.
What helps with tiredness on a GLP-1 medication?
Small, regular meals with enough protein, plenty of fluids, good sleep and regular activity. Ask your provider whether you need a vitamin, mineral or protein supplement and whether your other medicines need adjusting.
When should I worry about fatigue on a GLP-1?
Get help right away for confusion, dizziness, blurred vision or very little urine. Call your provider for signs of low blood sugar, ongoing vomiting or diarrhea, or fatigue that is severe or not improving.
Related guides
- GLP-1 supplements: do they work?
- GLP-1 muscle loss: how to keep muscle
- Matcha vs coffee: caffeine, jitters, stomach and sleep
- Does matcha have caffeine?
- Why caffeine crashes happen
- Should you work out with sore muscles?
Disclaimer and when to seek help
This article is for general education and is not medical advice. It does not replace advice from the clinician who prescribes your medication, and you should not start, stop or change any medication without talking to them. These statements have not been evaluated by the Food and Drug Administration. Our products are not intended to diagnose, treat, cure, or prevent any disease. Ozempic, Wegovy, Mounjaro and Zepbound are registered trademarks of their respective owners; OurJrney is not affiliated with them.
References
- Zepbound (tirzepatide) prescribing information. DailyMed, U.S. National Library of Medicine. dailymed.nlm.nih.gov
- Wegovy (semaglutide) prescribing information. DailyMed, U.S. National Library of Medicine. dailymed.nlm.nih.gov
- Ozempic (semaglutide) prescribing information and Medication Guide. DailyMed, U.S. National Library of Medicine. dailymed.nlm.nih.gov
- Mozaffarian D, et al. "Nutritional priorities to support GLP-1 therapy for obesity: a joint Advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society." American Journal of Clinical Nutrition, 2025;122(1):344-367. doi:10.1016/j.ajcnut.2025.04.023
- MedlinePlus (U.S. National Library of Medicine). "Fatigue".
- MedlinePlus (U.S. National Library of Medicine). "Caffeine".
