Key takeaways:
Fatigue has been reported with injectable Wegovy. It’s not clear how common it is or how long it lasts.
Wegovy-related fatigue is likely due to gut side effects, which can lead to dehydration, reduced food intake, or disrupted sleep.
Wegovy fatigue should get better as other side effects, like vomiting and nausea, get better. Talk with your healthcare team if fatigue lasts longer than 2 weeks.
Wegovy (semaglutide) is an FDA-approved treatment often used for weight management. But some people notice changes in their energy levels after starting it. Feeling more tired than usual can be frustrating.
Here’s what to know about Wegovy and fatigue, including why it may happen and what you can do to beat it.
Does Wegovy make you tired?
Wegovy has been linked to fatigue. But this side effect can be difficult to understand. That’s because “fatigue” isn’t defined the same way across studies. It can also mean different things to the people in the studies.
Fatigue can refer to a wide range of symptoms, including:
Lower stamina
Feeling more tired during activity
Less physical strength
Lower energy levels
Trouble concentrating
General tiredness
Depending on how researchers define fatigue, they may not capture all of these experiences. So studies may under- or overestimate what people actually feel in daily life. That makes fatigue harder to study than other side effects like nausea or diarrhea.
But with that in mind, research suggests there’s a connection between fatigue and injectable Wegovy.
In clinical trials, fatigue was one of the more commonly reported side effects. About 1 in 10 people taking injectable Wegovy reported fatigue. People taking Wegovy were about twice as likely to report fatigue as those taking a placebo (no medication). Real-world studies show similar findings. This suggests fatigue is a common experience for people using injectable Wegovy.
There’s no research yet showing a similar connection between oral Wegovy and fatigue. That doesn’t mean people who take oral Wegovy don’t experience fatigue. Oral Wegovy is newer, and studies may not be capturing this side effect. New research may help clarify the relationship between oral Wegovy and fatigue.
But here’s a positive note: Most people kept taking Wegovy even if they experienced side effects, including fatigue. This suggests that Wegovy-related fatigue is usually mild. For most people, it’s not severe enough to interrupt daily life. It also suggests that many people feel the benefits of Wegovy outweigh the side effects.
Why does Wegovy make you tired?
Researchers haven’t directly studied how Wegovy may cause fatigue. So it’s not clear whether Wegovy itself causes tiredness or low energy. Fatigue is more likely related to how Wegovy affects your body, especially through its side effects.
For many people, more than one factor may be involved. Symptoms may come back or get worse during dose increases, when side effects are often stronger. Here are several possible ways Wegovy may lead to fatigue.
Wegovy can lead to dehydration
Feeling tired while taking Wegovy may be linked to gastrointestinal side effects, not the medication itself. About half of people experience gastrointestinal side effects, like nausea, vomiting, and diarrhea, when taking Wegovy.
These symptoms can cause fatigue on their own. Vomiting and diarrhea can also lead to dehydration, which often causes tiredness, low energy, and sluggishness.
Wegovy can lead to electrolyte imbalances
Fatigue may be related to temporary changes in electrolytes caused by gut-related side effects. Vomiting and diarrhea can lead to electrolyte imbalances, especially if symptoms last for several days.
Electrolytes help control muscle and nerve function. Severe imbalances can be dangerous. But mild electrolyte changes can cause symptoms like fatigue, weakness, or feeling run down.
Wegovy makes you eat less
Low energy may be due to eating less food, not a direct effect of Wegovy.
Wegovy lowers appetite and makes you feel full faster, which supports weight loss. But eating too few calories can also lower energy levels. You’re more likely to feel tired if your body doesn’t get enough fuel to support daily activities.
Eating less protein may also play a role. Protein helps maintain muscle mass and supports energy levels. Not getting enough protein can lead to weakness, reduced stamina, and tiredness.
Other side effects can disrupt sleep
Wegovy doesn’t appear to directly affect sleep. But it slows stomach emptying, which can worsen acid reflux or heartburn for some people. Heartburn often feels worse when lying down, which can make it harder to sleep. Poor sleep can then lead to daytime fatigue.
How long does fatigue last when taking Wegovy?
It’s not clear how long Wegovy fatigue lasts.
In many clinical trials, fatigue wasn’t always tracked or reported. Even in clinical trials that mentioned fatigue, researchers didn’t look at when fatigue started, how long it lasted, or whether it improved as other side effects got better.
Because of this, it’s hard to know what to expect from Wegovy-related fatigue. If fatigue is caused by gastrointestinal symptoms — like nausea, vomiting, or diarrhea — it may get better as those symptoms go away.
In clinical trials, nausea and vomiting from Wegovy lasted between 2 and 13 days. Based on this, it’s likely that Wegovy fatigue may last anywhere from a week to several weeks. But it’s impossible to know for sure without more research.
Fatigue may also come back or get worse during dose increases, especially if gut side effects also come back or get worse.
How can you keep your energy up while taking Wegovy?
Wegovy-related fatigue is likely tied to other side effects. The best way to feel more energized is to support your body as it adjusts to the medication. Here are some tips to help you beat Wegovy fatigue.
Prioritize restful sleep
Getting enough high-quality sleep helps restore energy. Try to go to bed and wake up at the same time each day, even on weekends. If heartburn, nausea, or stomach discomfort wakes you up at night, talk with your healthcare team about ways to reduce these symptoms. Better sleep can make a noticeable difference in daytime fatigue.
Stay well hydrated
Wegovy can lower thirst. You may also lose fluids if you have vomiting or diarrhea. Even if you don’t feel thirsty, your body still needs fluids to function. Drink water throughout the day to help prevent dehydration, which is a common cause of tiredness. Using reminders or carrying a refillable water bottle can make this easier.
Make nutrition count
Wegovy often reduces appetite and helps you feel full faster. When you eat less, food quality matters more. Try to include enough protein in your meals to support muscle strength and energy. Getting enough fiber, vitamins, and minerals also helps your body produce energy. If eating feels difficult, a registered dietitian can help you plan balanced meals that fit your appetite.
Keep moving
Low energy can make exercise feel hard. But light activity can actually help reduce fatigue. Gentle movement, such as walking, stretching, or light strengthening exercises, can boost energy over time. You don’t need intense workouts. Staying consistent matters more than working out hard.
When to seek care for Wegovy fatigue
Let your healthcare team know if you’re feeling tired or fatigued while taking Wegovy. They can help determine whether it’s related to Wegovy or to something else, such as dehydration, low food intake, or other side effects.
In some cases, your care team may check for low blood sugar (hypoglycemia). This can be an issue if you have diabetes and take insulin or other diabetes medications.
Your healthcare team may also help adjust your treatment plan if needed. This may include slowing down how quickly your dose is increased or treating side effects that may be contributing to fatigue.
Don’t stop taking Wegovy on your own. Stopping treatment suddenly may increase side effects or affect how well the medication works. Always talk with your healthcare team before making any changes to your medication.
Frequently asked questions
You can take injectable Wegovy at any time of day. The timing doesn’t affect how well it works. The most important thing is to take your injection on the same day each week.
Oral Wegovy is different. It must be taken in the morning on an empty stomach with about 4 oz of water. Don’t take it with other liquids. After taking it, wait at least 30 minutes before eating, drinking, or taking other medications.
Wegovy may impact your energy levels. Fatigue can cause you to sleep more. Staying well hydrated, choosing high-quality nutrition, and staying active may help keep your energy up as your body adjusts to Wegovy. Talk with your healthcare team if your energy levels don’t improve within a week.
You can take injectable Wegovy at any time of day. The timing doesn’t affect how well it works. The most important thing is to take your injection on the same day each week.
Oral Wegovy is different. It must be taken in the morning on an empty stomach with about 4 oz of water. Don’t take it with other liquids. After taking it, wait at least 30 minutes before eating, drinking, or taking other medications.
Wegovy may impact your energy levels. Fatigue can cause you to sleep more. Staying well hydrated, choosing high-quality nutrition, and staying active may help keep your energy up as your body adjusts to Wegovy. Talk with your healthcare team if your energy levels don’t improve within a week.
The bottom line
Some people taking Wegovy report fatigue. But this side effect hasn’t been studied as closely as others, and it can mean different things to different people. Available evidence suggests fatigue is linked to side effects like nausea, dehydration, eating less, or poor sleep. Wegovy-related fatigue should get better as other side effects improve. Talk with your healthcare team if your fatigue continues, is severe, or affects your daily life. They can make sure Wegovy is the right choice for you.
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References
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MedlinePlus. (2025). Fatigue.
Novo Nordisk. (2026). Wegovy- semaglutide injection, solution Wegovy- semaglutide tablet [Package insert]. DailyMed.
Wadden, T. A., et al. (2021). Effect of subcutaneous semaglutide vs placebo as an adjunct to intensive behavioral therapy on body weight in adults with overweight or obesity: The STEP 3 randomized clinical trial. JAMA.
Wadden, T. A., et al. (2024). Psychiatric safety of semaglutide for weight management in people without known major psychopathology: Post hoc analysis of the STEP 1, 2, 3, and 5 trials. JAMA Internal Medicine.
Wharton, S., et al. (2025). Oral semaglutide at a dose of 25 mg in adults with overweight or obesity. The New England Journal of Medicine.
