Does Wegovy Make You Tired? Why It Happens and What Helps

Short answer: yes, it can. The UK product information for Wegovy lists feeling weak or tired as a very common side effect, which means it may affect more than 1 in 10 people. It is mainly seen while the dose is being increased, and the leaflet says it usually goes away over time. Eating much less than before, not drinking enough and stomach side effects can all add to it, and there are practical steps for each.

This guide sets out how common tiredness is on Wegovy, when it tends to happen, the likely reasons, what helps, and when tiredness is a reason to speak to your pharmacist or GP. The figures are from the UK product information and the trials' published results, as of October 2026.

Is tiredness a side effect of Wegovy?

Yes. The UK product information puts fatigue in its highest frequency band, very common, which means more than 1 in 10 people. The figure counts related words together, such as feeling tired and feeling weak, and comes from the four main trials of Wegovy 2.4mg, each 68 weeks long. The NHS also lists feeling tired as a common side effect of semaglutide, the medicine in Wegovy.

• UK product information1 in 10+

  Feeling weak or tired is very common on Wegovy: it may affect more than 1 in 10 people.

• STEP 1 trial, 68 weeks8.0%

  of people on Wegovy 2.4mg reported fatigue, against 4.3% of people on placebo.

Other side effects in the product information can leave you tired or low on energy too:

The bands are from the Wegovy product information and patient leaflet. Our guide to Wegovy side effects covers the full list.

How common is tiredness in the Wegovy trials?

Each of the main trials posted its results on ClinicalTrials.gov, including how many people reported fatigue as a side effect. These figures count the single word "fatigue", which is why they are a little lower than the product information's grouped figure.

In every trial, some people taking the placebo reported tiredness too, though fewer than on Wegovy. In STEP 1 and 2, everyone, on Wegovy or placebo, was asked to follow a reduced-calorie diet and be more active, and in STEP 3 everyone started on a low-calorie diet. Individual experiences vary.

Does Wegovy fatigue go away?

Usually, yes. The product information says tiredness is mainly seen during the dose-escalation period, the weeks when the dose is being stepped up, and the patient leaflet says it usually goes away over time.

The STEP 4 trial shows the pattern. Everyone first spent 20 weeks building up to 2.4mg, and 7.4% reported fatigue in that time. Over the next 48 weeks, 4.9% of those who stayed on Wegovy reported it, against 2.2% of those switched to placebo.

The product information does not single out one dose step. Tiredness that is getting worse rather than better, or that carries on well after your dose has settled, is worth raising with your pharmacist rather than pushing through. Our Wegovy dose schedule explains each step.

Why does Wegovy make you tired?

Often more than one thing is going on. These are the likely reasons, with what the evidence says about each.

• You are eating much less. Wegovy turns appetite down. In a study in the UK product information, people ate 35% less at a meal after 20 weeks on Wegovy 2.4mg than people on placebo. Less food can mean less energy.

• Protein falls with it. When you eat less of everything, you eat less protein too. A 2025 joint advisory from four obesity and nutrition societies notes that enough protein can be hard to reach on these medicines because appetite is lower.

• Feeling sick makes eating harder. In the main trials, nausea affected 43.9% of people on Wegovy 2.4mg, mostly while the dose was going up. The same advisory describes a cycle: not eating because you feel sick can make the sickness worse, which makes eating even less likely.

• You may be short of fluid. Food provides some of your fluid, so eating less means taking in less, and being sick or having diarrhoea loses more. The NHS lists feeling tired among the symptoms of dehydration, and the Wegovy leaflet asks you to drink enough to prevent it.

• Low blood sugar, if you have diabetes. Low blood sugar is common in people with diabetes on Wegovy, and more likely if you also take a sulfonylurea or insulin. Feeling sleepy or weak is one of its warning signs. In people without diabetes it is uncommon.

• Poor sleep. The NHS names not getting enough sleep among the common causes of tiredness. Loud snoring with gasping or choking at night, and tiredness in the day, can be a sign of sleep apnoea, which is worth getting checked.

• Low iron or vitamin B12. Eating less for months can leave gaps. The 2025 advisory names iron and vitamin B12 among the nutrients of concern on these medicines, and lists fatigue beyond what you would expect as a sign of a deficiency. A blood test is how to find out.

• Something unrelated to Wegovy. Tiredness has many causes: stress, low mood or depression, hormonal changes such as the menopause, an underactive or overactive thyroid, diabetes, and some other medicines. Starting Wegovy does not rule any of them out.

How to combat fatigue on Wegovy

1. Eat little and often. The NHS suggests regular meals and healthy snacks every 3 to 4 hours to keep your energy up, and the 2025 advisory suggests a small breakfast, then small meals every 3 to 4 hours, with enough to drink. Try not to go most of the day without eating.

2. Put protein first. Start each meal with its protein, such as eggs, yoghurt, fish, chicken, tofu, beans or lentils, so that if you only manage half, you have had the half that counts. The advisory suggests 80 to 120g of protein a day. If you have kidney disease, check with your GP or pharmacist before you eat more protein.

3. Drink through the day. The NHS suggests 6 to 8 cups or glasses of fluid a day, enough for your pee to be a pale yellow, and more if you are being sick or have diarrhoea. If you feel sick, start with small sips. A pharmacist can recommend an oral rehydration solution if you are losing a lot of fluid.

4. Keep moving, starting small. The NHS says regular exercise makes you feel less tired in the long run, and that even a single 15-minute walk can give you an energy boost. Build up towards 150 minutes of moderate activity a week, with strength exercises on at least 2 days, which the 2025 advisory recommends to help keep muscle while you lose weight.

5. Protect your sleep. The NHS suggests keeping to the same sleep times, aiming for 6 to 9 hours, relaxing for a couple of hours before bed and avoiding screens in the hour before. Caffeine's effects can last up to 7 hours, so keep tea, coffee and energy drinks to earlier in the day.

6. Go easy on alcohol. The NHS advises that it is best not to drink alcohol on semaglutide, because it can make feeling or being sick worse, and not drinking too much is part of its advice on tiredness too.

7. Do not rush the next dose step. If tiredness comes with stomach side effects and a step feels hard, tell your pharmacist before your next increase. The UK product information allows delaying the next step, or going back to the previous dose, until stomach symptoms have improved. Your pharmacist reviews you before each increase.

8. Ask about a blood test if it does not lift. If you have felt tired for a few weeks and are not sure why, the NHS advises seeing a GP. Blood tests can check for anaemia, diabetes and thyroid problems.

For meal ideas, see what to eat on Wegovy and our simple recipes for small portions, each showing about how much protein a portion has. If you are eating much less than before, our guide to vitamins and supplements on Mounjaro or Wegovy explains which nutrients can fall short and what to do about it.

Is it Wegovy, or something else?

When is tiredness on Wegovy a reason to get help?

Speak to your pharmacist or GP if:

• your tiredness is getting worse rather than better, or is affecting your daily life
• you have felt tired for a few weeks and are not sure why
• you feel tired and have other symptoms, such as changes in your mood, or you have been told you make gasping, snorting or choking noises in your sleep
• you are short of breath, notice your heartbeat, or look paler than usual, which can be signs of iron deficiency anaemia
• you have a sore, red tongue or pins and needles, which can be signs of low vitamin B12

If you feel dizzy, do not drive or use machines until you feel better, as the Wegovy leaflet advises. Some symptoms need help straight away, whatever the cause: they are in the box at the end of this guide, with the signs of dehydration and of low blood sugar. For urgent medical concerns, call NHS 111 or 999. Our help centre explains what to do if it's urgent.

Should you stop Wegovy if it makes you tired?

Not on your own. The NHS advice for semaglutide is to keep taking your medicine unless you are advised to stop, and to speak to a pharmacist or doctor about side effects that bother you or do not go away. Many of the reasons above can be changed, and staying on your current dose for longer is an option your pharmacist can talk through with you.

Tell your pharmacist about any side effect that worries you. You can also report suspected side effects to the MHRA through the Yellow Card scheme.

Do Wegovy tablets make you tired too?

Wegovy tablets contain the same medicine, semaglutide, taken once a day. Their product information lists tiredness among their side effects too, and the same reasons and fixes apply. Our guide to oral semaglutide side effects covers the tablets in full.

Does Wegovy make you more tired than Mounjaro?

There is no clear answer. In SURMOUNT-5, a trial that compared the two directly over 72 weeks, fatigue was reported by 12.2% of people on semaglutide (up to 2.4mg), the medicine in Wegovy, and 10.4% on tirzepatide (up to 15mg), the medicine in Mounjaro. The trial was not set up to compare tiredness, and everyone knew which medicine they were taking.

The UK product information lists tiredness as very common for Wegovy and as common in Mounjaro's weight-management trials. Those bands come from different trials, so they are not a fair comparison either. Our guide to whether Mounjaro makes you tired covers Mounjaro.

See also Wegovy side effects, is Wegovy safe? and the Wegovy dose schedule.