Wegovy Side Effects: What Is Common, What Is Serious and What Helps (November 2026)

01 · When to get help

When to get urgent medical help

Serious side effects of semaglutide include a severe allergic reaction (anaphylaxis), acute pancreatitis, worsening diabetic eye disease, low blood sugar, and sudden loss of vision, usually in one eye.¹ Seek immediate help for severe, persistent stomach pain that may spread to your back, with or without vomiting; swelling of the face, lips or throat or difficulty breathing; or a sudden change in your eyesight. If you think you may be having a serious side effect, call NHS 111 or, in an emergency, 999.

02 · Support

Talking to the prescribing team

For side effects that are not an emergency but are bothering you, contact the prescribing team. They may suggest ways to manage them or staying on your current dose for longer. Wegovy (semaglutide) is a prescription-only medicine, supplied only after an online consultation reviewed by a GPhC-registered prescriber. This page is information, not a substitute for medical advice. Always read the leaflet that comes with your medicine.

03 · Common side effects

Common Wegovy side effects

Common side effects include nausea and vomiting, constipation, diarrhoea, tiredness, itchy or red skin where you inject, and hair loss.¹ In STEP 1, gastrointestinal side effects were reported by 74.2% of people on semaglutide 2.4mg, compared with 47.9% on placebo.²

Wegovy slows the rate at which your stomach empties and reduces appetite.³ That is why digestive side effects are most likely in the first weeks and in the days after each dose increase, and why they usually ease as your body adjusts.

04 · Managing nausea

How to manage nausea on Wegovy

• Eat smaller meals slowly and stop at the first feeling of fullness.
• Favour plain, lower-fat foods while adjusting; go easy on fried, fatty and very sweet food.
• Sip fluids through the day rather than drinking a lot at once.
• Avoid lying down straight after eating.

If nausea is severe or stops you eating and drinking, contact the prescribing team.

05 · Constipation and diarrhoea

Constipation and diarrhoea

Constipation is common because digestion slows. Increase fibre gradually, drink more fluids and stay active. If it lasts more than a few days or is painful, ask a pharmacist or the prescribing team about a suitable laxative.

Diarrhoea can lead to dehydration. Drink plenty of fluids and choose plainer foods until it settles, and seek advice if diarrhoea or vomiting is severe or lasts more than a day or two.

06 · Tiredness and hair loss

Tiredness and hair loss

Tiredness and hair loss are both listed as common.¹ Eating too little, not drinking enough and losing weight quickly can all contribute. Make sure meals include enough protein, avoid very restrictive eating, and drink enough fluid. Hair shedding linked to weight loss is usually temporary. If you are worried, or hair loss is patchy or sudden, speak to the prescribing team or your GP.

07 · Injection site reactions

Injection site reactions

Itchy or red skin where you inject can happen and usually settles within a few days.¹ Inject into the fatty areas of your thigh, tummy or upper arm; you can use the same area, but not the exact same spot each time.¹ Our guide on how to inject Wegovy explains how to rotate.

08 · Alcohol

Wegovy and alcohol

It is best not to drink alcohol, because it can increase side effects such as feeling or being sick.¹ If you do drink, keep it light, eat with it, and avoid drinking on days when your stomach is unsettled.

09 · Mood

Mood and mental health

Regulators have looked at whether GLP-1 medicines are linked to low mood or suicidal thoughts: in 2024 the MHRA concluded that the available evidence does not support a causal link, and it continues to monitor this closely.⁴ Tell the prescribing team or your GP if you notice changes in your mood.

10 · Pregnancy

Pregnancy and contraception

If there is a chance you could get pregnant, use contraception while you are using semaglutide. If you want to become pregnant, stop using it at least 2 months before you start trying.¹

11 · Do side effects go away?

Do Wegovy side effects go away?

For most people, yes. Digestive side effects are usually worst in the first weeks and after a dose increase, then ease. The dose steps up after 4 weeks on each of 0.25mg, 0.5mg, 1mg and 1.7mg, so the 2.4mg maintenance dose starts from week 17,³ and the prescriber may keep you on a dose for longer if side effects need time to settle. You can see how the dose steps up in our Wegovy dose schedule.

You can report side effects through the MHRA Yellow Card scheme, which helps monitor the safety of medicines.⁵