Wegovy and tiredness: is sleepiness a side effect of semaglutide?

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Can Wegovy make you sleepy? Learn everything you need to know about Wegovy and tiredness in our guide.

Wegovy (semaglutide) is an injection you take once a week to help you lose weight.

It works by simulating natural hormones in your body that help digest food and regulate appetite. That means you'll feel satisfied eating smaller portions. It also helps control your blood sugar, reducing the risk of hunger-inducing glucose spikes.

This revolutionary drug helps people lose 15% of their starting weight on average. However, like any medication, it can cause side effects – one being tiredness, especially during the first few months.

Tiredness: a common side effect of Wegovy

Tiredness is listed as a side effect on the Wegovy patient information leaflet and is said to affect more than one in 10 people.

The good news? It usually gets better by around the eighth week of treatment. That's because your body gets used to the medication over time.

You may experience it again to a lesser extent when you increase your dosage. However, this is less likely if you increase your dose gradually in line with recommendations.

Do you have type 2 diabetes?

If you are taking Wegovy and have type 2 diabetes, feeling unusually fatigued could be a sign of hypoglycaemia. Keep a close eye on your blood sugar levels and ask your healthcare provider for advice.

What can help with Wegovy and tiredness?

If you are experiencing tiredness with semaglutide, there are some easy steps you can take to feel more energised.

1. Stay hydrated

If you're dehydrated, your body can struggle to work as it should. This can cause you to feel tired.

Dealing with other potential side effects like nausea and diarrhoea can make this even worse, so make sure you're staying as hydrated as possible. Keep a water bottle nearby and sip regularly throughout the day.

2. Support electrolytes

Electrolytes like sodium, potassium and magnesium are vital for energy. Eating less food or drinking more water without replacing these minerals can leave you feeling drained.

A balanced diet usually provides enough of these vital minerals. However, if tiredness persists, ask your GP or SemaPen team about electrolyte support.

3. Eat smaller, balanced meals

Wegovy will naturally make you want to eat smaller portions. However, not eating enough calories or getting the right nutrition throughout the day can make you tired.

Use the SemaPen app or check out the NHS Eatwell Guide for advice on a healthy, balanced diet. And if you're feeling sick, try eating six smaller meals instead of two large ones.

4. Move gently

We know exercising can feel like a chore when you're tired, but it can actually make you feel more energised. Even a brisk 15-minute walk can improve energy by increasing blood flow and oxygen to muscles and the brain.

5. Improve sleep quality

Taking Wegovy can sometimes disrupt sleep patterns, especially on the day you inject.

A regular bedtime, no caffeine after lunch and avoiding looking at your phone before bed can make it easier to get a good night's rest.

If you follow these tips and still feel tired, speak to your GP, healthcare provider or weight loss consultant. And remember: as a SemaPen subscriber, you have direct access to expert support from our team. Please don't hesitate to reach out to us with any questions.

Sources

1. Wilding, J.P.H. et al. (2021) "Once-weekly semaglutide in adults with overweight or obesity" The New England Journal of Medicine, 384(11) https://doi.org/10.1056/NEJMoa2032183

This article was reviewed and approved by Lujain Alhassan, Bariatric Nutritionist, on 31 October 2025.

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