Wegovy Side Effects: What to Expect at Each Dose and When to Seek Help
Dr. Hecham Harb
Consultant Endocrinologist & Medical Director
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The most commonly reported side effects of Wegovy are nausea, diarrhoea, vomiting, constipation and abdominal pain. Not every patient experiences these side effects. Your endocrinologist can slow the pace of dose increases and, where needed, prescribe medication to help manage nausea, vomiting or constipation. Severe stomach pain that does not go away, a serious allergic reaction or being unable to keep fluids down needs urgent medical care.
- In the Wegovy prescribing information, nausea was reported by 44% of adults on 2.4 mg, compared with 16% on placebo.
- The prescribing information reports that 4.3% of adults stopped the Wegovy injection because of digestive side effects, compared with 0.7% on placebo.
- Your endocrinologist will agree each dose increase with you, taking into account how well you tolerate the current dose.
- The UK product information states that the safety profile of the Wegovy pill was consistent with that seen in the trials of the Wegovy injection.
- The prescribing information reports hair loss in 3% of adults on the Wegovy injection, compared with 1% on placebo.
- Between monthly follow-ups, Endocare’s doctors can advise you on side effects, for example on when to take your next injection.
- The prescribing information advises stopping Wegovy at least two months before a planned pregnancy.
01 Introduction
Wegovy comes in two forms: the Wegovy injection, taken once a week, and the Wegovy pill, taken once a day. Both contain semaglutide.
02 What are the common side effects of Wegovy?
The Wegovy prescribing information reports the following side effects in adults taking the Wegovy injection at 2.4 mg in clinical trials, compared with placebo.
| Side effect | Wegovy injection 2.4 mg | Placebo |
|---|---|---|
| Nausea | 44% | 16% |
| Diarrhoea | 30% | 16% |
| Vomiting | 24% | 6% |
| Constipation | 24% | 11% |
| Abdominal pain | 20% | 10% |
| Headache | 14% | 10% |
| Fatigue | 11% | 5% |
| Indigestion | 9% | 3% |
| Dizziness | 8% | 4% |
| Hair loss | 3% | 1% |
Most of these side effects are digestive, and each was also reported by some people taking a placebo. Not every patient experiences them.
03 How Wegovy side effects change as the dose increases
The Wegovy injection starts at 0.25 mg once weekly, with dose steps of at least four weeks towards 2.4 mg. The prescribing information states that digestive side effects were most frequently reported while the dose was being increased.
The prescribing information sets an increase every four weeks, and your endocrinologist will agree each increase with you at your monthly follow-up. If you do not tolerate a dose, the prescribing information suggests delaying the next increase for four weeks. Our Wegovy dosage guide explains each step.
04 How long do Wegovy side effects last?
Side effects such as nausea or constipation can be particularly pronounced in the first few days at a new dose. Side effects often ease over time, but some people experience them for longer. Your endocrinologist will review them with you at your follow-up.
In the clinical trials described in the prescribing information, 4.3% of adults taking the Wegovy injection stopped because of digestive side effects, compared with 0.7% of adults taking a placebo.
05 How Wegovy side effects are managed at Endocare
If you experience nausea or constipation, your endocrinologist can adjust the pace of dose increases and, where needed, prescribe medication to help manage these side effects. Endocare’s doctors are always available to support patients with advice, for example by adjusting the timing of the next injection. Monthly follow-up appointments can be held in person at the clinic or online.
Endocare’s lifestyle coaches can help you adjust the size of your meals and your food choices while your body gets used to a new dose. Our guide to what to eat on Wegovy covers practical meal choices. We recommend drinking enough fluid, particularly if you have vomiting or diarrhoea, because losing fluid can affect the kidneys.
If you have type 2 diabetes, your endocrinologist prescribes Wegovy for weight management, and it does not replace your diabetes treatment. Your endocrinologist will review the glucose-lowering medications you take, because insulin or a sulfonylurea taken with Wegovy can increase the risk of low blood sugar. Do not stop Wegovy without a plan agreed with your endocrinologist, because stopping can worsen blood sugar control.
06 Side effects of the Wegovy pill
The UK product information states that the safety profile of the Wegovy pill was consistent with that seen in the trials of the Wegovy injection. In a 64-week trial of the 25 mg pill, OASIS 4, digestive side effects led 3.4% of the 204 adults taking the pill to stop treatment permanently. The trial included adults with obesity, or with overweight and at least one weight-related condition.
The Wegovy pill is taken in the morning on an empty stomach, with up to half a cup of plain water. The morning timing comes from the US prescribing information, and the UK product information sets no time of day. Wait at least 30 minutes before eating, drinking or taking other medications. Our page on the Wegovy pill explains how to take it in full.
07 Serious side effects of Wegovy: when to seek medical advice
Serious side effects are much less common than digestive side effects. The prescribing information carries warnings for each of the following symptoms:
- Severe stomach pain that does not go away, with or without vomiting, which can be a sign of pancreatitis. Seek medical advice immediately
- Pain in the upper right side of the abdomen, fever or yellowing of the skin or eyes, which can be signs of a gallbladder problem. Seek medical advice immediately
- Persistent vomiting or diarrhoea with signs of dehydration, such as passing very little urine. Seek medical advice immediately
Swelling of the face, lips, tongue or throat, or difficulty breathing, can be signs of a serious allergic reaction. Call an ambulance on 998.
In very rare cases, semaglutide has been linked to a sudden loss of vision in one eye. The Medicines and Healthcare products Regulatory Agency (MHRA) describes this condition as non-arteritic anterior ischaemic optic neuropathy (NAION). Seek urgent medical attention if you notice any sudden change in your eyesight.
08 Hair loss and other changes with weight loss on Wegovy
The prescribing information reports hair loss in 3% of adults taking the Wegovy injection, compared with 1% on placebo. In adolescents, it reports hair loss in 4%, compared with none on placebo.
Rapid weight loss, a large calorie deficit, illness or surgery can trigger hair shedding. These stresses can cause more hairs than usual to enter the resting phase together. The Cleveland Clinic describes this kind of shedding as often improving within three to six months. Our article on hair loss on GLP-1 medications explains the causes and what can help.
Substantial weight loss can also change the appearance of the face. Our article on facial changes after weight loss covers this in more detail.
09 Who may not be suitable for Wegovy?
Do not use Wegovy if you or a member of your family has had medullary thyroid carcinoma, or if you have multiple endocrine neoplasia syndrome type 2. The prescribing information lists both as reasons not to use semaglutide, together with a previous serious allergic reaction to it.
The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) advises never taking weight management medication during pregnancy or when planning a pregnancy. If you are planning a pregnancy, the prescribing information advises stopping Wegovy at least two months beforehand. The NIDDK also states that weight loss medication is not recommended while breastfeeding.
The prescribing information does not recommend Wegovy for people with severe gastroparesis. Do not use Wegovy together with Ozempic or any other GLP-1 medication. If you also take insulin or a sulfonylurea for diabetes, your endocrinologist will review your diabetes medication, because the combination can increase the risk of low blood sugar.
Patients should not decide by themselves to start a GLP-1 medication. A doctor’s review is critical to ensure the treatment is safe and appropriate for the individual.
10 FAQ
What is the main side effect of Wegovy?
Nausea. In the prescribing information, nausea was reported by 44% of adults taking the Wegovy injection at 2.4 mg, compared with 16% taking a placebo.
Does Wegovy cause stomach paralysis?
Wegovy can slow the emptying of the stomach, and the prescribing information does not recommend it for people with severe gastroparesis. Bowel obstruction and severe constipation are among the problems reported after approval, without a reliable estimate of how often they occur. Seek medical advice immediately if you have severe abdominal pain, persistent vomiting or severe constipation.
Can Wegovy affect my heart rate?
It can. The prescribing information reports mean increases in resting heart rate of 1 to 4 beats per minute in adults taking the Wegovy injection, compared with placebo. Tell your endocrinologist if you notice a racing or pounding heartbeat at rest.
Should I stop Wegovy if I feel sick?
We recommend contacting your endocrinologist before stopping. Nausea is common while the dose is rising, and your endocrinologist can adjust the pace of dose increases or prescribe medication to help. Seek medical advice immediately if you cannot keep fluids down.
Are Wegovy side effects the same as Ozempic side effects?
They are similar, because both medications contain semaglutide. The doses differ: Ozempic is approved for type 2 diabetes, and the Wegovy injection continues to higher doses for weight management. Our page on Ozempic side effects covers Ozempic in detail.
Is it safe to have surgery while taking Wegovy?
Tell your endocrinologist and your anaesthetist that you take Wegovy before any planned procedure that needs sedation or a general anaesthetic. Semaglutide slows the emptying of the stomach, which can increase the risk of inhaling stomach contents during anaesthesia. Your doctors will advise you on what to do before the procedure.
At our Dubai clinic, your endocrinologist will assess you, review any side effects and agree a plan with you. You can book a weight loss consultation on +971 4 285 3885 or send us a message on WhatsApp.
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