Navigating Wegovy Side Effects: What You Need to Know

Dr. Babak Ashrafi

Medically reviewed by

Dr Babak Ashrafi

Last reviewed: 17 Oct 2023

Wegovy keeps your appetite low and helps you to eat less. On average, patients lose 15% of their body weight within 68 weeks of treatment (combined with a healthy nutrition and sports program)(EMA, 2022). But as with every medication, there is a risk of side effects.

Most people won’t get side effects from Wegovy. The most common ones that people do get include nausea, stomach pain, vomiting or diarrhoea. Severe side effects like allergic reactions or inflammation of the pancreas are also possible, but rare. A change in food and eating habits can help to improve some side effects. We summarised everything you need to know about the side effects of Wegovy in this article.

➤ You can also find general information on Wegovy on our ‘what is Wegovy?‘ page.

Contents
Side effects of Wegovy weight loss injections
 

What are the side effects of Wegovy?

It may happen that you experience side effects during Wegovy treatment. The following list includes all side effects that doctors have found while testing the medication.

In some cases, side effects are not caused by Wegovy directly, but by the rapid weight loss it causes for some people. Gallstones for example are a common risk in people losing weight very quickly. Hair loss was also seen more often in people who lost a lot of weight.

The most common side effects of Wegovy

The most common side effects of Wegovy are related to the gut and digestion. According to the European Medicines Agency, around 44% of patients experience nausea and almost 30% have diarrhoea during their treatment. Semaglutide, the active ingredient in Wegovy, has a strong influence on the digestive tract – this is one of the ways it lowers hunger for people who use it.

Severe cases of nausea, vomiting or stomach pain may happen, but in most cases the side effects are mild and go away eventually. Many patients also experience headaches and tiredness while using Wegovy. Throughout studies testing semaglutide, 6.8% of the participants stopped treatment due to side effects they experienced.

Wegovy immediate side effects

Immediate side effects during Wegovy treatment mostly affect the digestive system, such as stomach pain, nausea, diarrhoea or constipation. Usually, they are strongest when the dose is escalated and go away once the body is used to the higher dosage. It’s important to drink a lot of water, even if you’re feeling nauseous. Vomiting and diarrhoea can easily cause dehydration, which over a prolonged time puts a strain on the kidneys.

What is ‘Ozempic Face’?

Some patients notice their face shape changing during Wegovy or Ozempic treatment. Their skin becomes a little more loose and makes the face sag. This effect is not caused by the medication directly, but is a typical consequence of rapid weight loss.

Wegovy long-term side effects

Wegovy is still a relatively new medication and it has only been approved for the UK since 2021. Even though semaglutide has been tested extensively to ensure it’s safe for its users, there is currently not much data on long-term side-effects. In the longest running study so far, semaglutide was tested for 2 years. Altogether 6% of the patients stopped the treatment due to its side effects and no new risks of the drug were found. In patients who received a placebo treatment without semaglutide, 4.6% also discontinued their treatment due to side effects.

Inflamed pancreas or gallstones

If Wegovy is being used for a prolonged time, patients should pay attention to signs of an inflamed pancreas or gallstones, such as strong abdominal pain and nausea, fever or jaundice. These complications should be treated by a doctor immediately.

Malnutrition

Another potential risk is malnutrition: Many patients eat less food when using Wegovy and might develop nutrient deficiencies. You can seek advice from your doctor and/or certified nutritionist if you’re unsure whether you should use supplements.

Thyroid tumours

In studies with Wegovy on mice and rats, researchers found more cases of thyroid C-cell tumours, some carcinogenic. This effect has not been seen in humans, but patients who develop any neck lumps or thyroid symptoms should seek medical advice before starting or continuing treatment.

Who should not take semaglutide?

Wegovy is only intended for patients who need to lose weight for their health. This includes people with a BMI higher than 30 kg/m2 or a BMI over 27 kg/m2 alongside weight-related health problems, such as high blood pressure or prediabetes.

You should not use Wegovy if you:

  • are allergic to any of its ingredients
  • are pregnant or breastfeeding
  • have severe heart failure

Because semaglutide increases the risk of acute pancreatitis, patients who had an inflammation of the pancreas before should be extra cautious and speak to their doctor before using Wegovy.

When do Wegovy side effects start?

This is different from person to person. While some patients can feel the effects of Wegovy from the first dose, it takes a few weeks in others. Some patients have very little to no side effects at all. According to research, most people will experience side effects within the first 10 weeks of using semaglutide.

How long do Wegovy side effects last?

How long Wegovy side effects last is highly individual and depends not only on the person, but also on the symptoms themselves. In clinical trials testing semaglutide, the median duration for vomiting was 2 days, for nausea 8 days and for constipation 47 days (EMA, 2022).

Most patients report side effects showing up when the dose is escalated. They often improve once the body gets used to the new dosage, but if they remain and/or are very strong, then going back to a lower dose might be a better option for you.

If you don’t adjust to Wegovy and the side effects are too strong for you, another weight loss medication might be better suited. At ZAVA, we can approve the following medications online:

  • Saxenda – injected once daily, it works by suppressing appetite (like Wegovy)
  • Orlistat – daily tablets which stop your body absorbing fat

To get your weight loss treatment, you just need to fill in a short online questionnaire. Our doctors then check if the medication is right for you. If it is, you will receive your treatment by post, at your preferred address.

Do the side effects of Wegovy go away?

Yes, most of the time the side effects of Wegovy go away by themselves without any need for extra medical support. This often happens as the body gets used to higher levels of the medication. Just make sure you stay well hydrated if you have vomiting and/or diarrhoea. If the side effects do remain and interfere with your everyday life, switching to a lower dose or stopping treatment might be a better option for you.

Some side effects of Wegovy for weight loss are serious and require immediate medical attention as soon as they occur:

  • acute pancreatitis (symptoms include severe ongoing pain in upper stomach)
  • gallstones (symptoms include sudden pain in upper stomach or back, nausea, vomiting and cramping)
  • complications with diabetic retinopathy or severe hypoglycaemia in diabetes patients
  • severe allergic reactions (shortness of breath, hives, swelling of face, mouth or throat and loss of consciousness)

Wegovy side effects with alcohol

Even though alcohol does not react directly with semaglutide, it might make Wegovy side effects worse. This is because alcohol itself can disturb the stomach and trigger nausea or vomiting, which are also common side effects of Wegovy injections. Together the effects could potentially add up and make side effects more likely and stronger.

Additionally, alcohol and semaglutide both lower the blood sugar, which increases the risk for hypoglycemia (low blood sugar). We advise you to avoid drinking during the treatment. If you would like to drink alcohol anyway, it’s best not to do it in the first days after an injection and especially not after a dose increase.

Comparing the side effects of Wegovy to other treatments

Wegovy generally has very similar side effects to other weight loss or diabetes medications that have a similar mechanism of action.

Saxenda vs Wegovy side effects

Saxenda and Wegovy are both weight loss injections from the same manufacturer. Saxenda uses a different active ingredient, liraglutide.

Wegovy Saxenda
Most common side effects
  • Headache
  • Nausea 
  • Vomiting
  • Diarrhoea
  • Stomach pain
  • Constipation
  • Feeling weak or tired
  • Headache
  • Nausea 
  • Vomiting
  • Diarrhoea
Serious side effects
  • Inflamed pancreas
  • Severe allergic reactions
  • Eye problems (in diabetes patients)
  • Inflamed pancreas
  • Severe allergic reactions

Wegovy vs Mounjaro side effects

Wegovy and Mounjaro also have a similar mechanism of action. However, Mounjaro has been developed more recently and is so far only approved for treatment of type 2 diabetes in the UK. Due to shortages it hasn’t yet entered the UK market, so it’s currently not legally available.

Wegovy Mounjaro
Most common side effects
  • Nausea 
  • Diarrhoea
  • Headache
  • Vomiting
  • Stomach pain
  • Constipation
  • Feeling weak or tired
  • Nausea 
  • Diarrhoea
  • Low blood sugar (in diabetes patients)
Serious side effects
  • Inflamed pancreas
  • Severe allergic reactions
  • Eye problems (in diabetes patients)
  • Inflamed pancreas

Ozempic vs Wegovy side effects

Ozempic and Wegovy both contain the same active ingredient semaglutide. Ozempic was developed for the treatment of type 2 diabetes, while Wegovy is intended for weight loss. Differences in side effects are mainly due to the non-active ingredients and the different dosagesWegovy for weight loss is taken in doses of up to 2.4 mg, but the highest dose of Ozempic is 1.0 mg.

Wegovy Ozempic
Most common side effects
  • Nausea 
  • Diarrhoea
  • Headache
  • Vomiting
  • Stomach pain
  • Constipation
  • Feeling weak or tired
  • Nausea
  • Diarrhoea
  • Low blood sugar (when used with insulin or sulfonylurea)
Serious side effects
  • Inflamed pancreas
  • Severe allergic reactions
  • Eye problems (in diabetes patients)
  • Inflamed pancreas
  • Severe allergic reactions
  • Eye problems (in diabetes patients)

How to avoid Wegovy side effects

A few actions can help you to avoid or alleviate the side effects of Wegovy:

  • eat smaller portions
  • eat slowly and stop eating once you feel satiated
  • drink a lot of water
  • change to another injection time/day (not right before big meals)
  • eat bland, starchy foods if you feel nauseous
  • avoid fatty and fried foods
  • avoid spicy food
  • don’t lay down after eating, take a walk instead

Feelings of dizziness might be caused by low blood sugar – you can try to combat this by eating or drinking something sweet, such as fruit or fruit juice. If you experience this side effect frequently, you should get your blood sugar levels checked at your doctor’s.

It is also really important to go slow on the dose increases and listen to your body and your doctor’s instructions. While it may be tempting to increase the dose quickly and have fast results, this can cause severe side effects and discomfort. The more time you give your body to adjust to the medication, the better it will get on with it.

Conclusion

The side effects patients experience on Wegovy are highly individual. Most commonly people get problems with the stomach and digestion, such as nausea, vomiting, diarrhoea or stomach pain. These symptoms often show up when the dosage is increased and improve once the body is used to the higher levels of semaglutide. But, in some people side effects are so strong that they prefer to lower the dose or stop the medication altogether. Others experience no side effects at all. A change in eating habits can help to prevent or improve some side effects.

Frequently asked questions

Does Wegovy cause hair loss?

Yes, Wegovy causes hair loss in 2.5% of patients (EMA, 2022). Hair loss is seen more often in patients who lost a lot of weight very quickly. It also tends to be reversible after stopping Wegovy.

How common is depression with Wegovy?

Cases of depression during Wegovy usage have come up only recently and not very often. Since the issue hasn’t been fully studied, it’s too soon to tell how common it is and how exactly it is related to Wegovy.

Is dehydration a side effect of Wegovy?

Yes, dehydration can indirectly become a side effect of Wegovy. If patients suffer from vomiting and diarrhoea and don’t drink enough fluids to balance the water loss, it can lead to dehydration and loss of electrolytes. Make sure you drink enough water during treatment, even if you feel nauseous.

Does Wegovy cause thyroid issues?

Wegovy has caused thyroid tumours in rats and mice. In clinical trials with humans, no effects on the thyroid gland have been found.

What foods to avoid while taking semaglutide?

While taking semaglutide, you should avoid eating foods that are very fatty and/or spicy, such as fried foods or fast food. Heavy meals and overeating can trigger side effects such as nausea, stomach pain or acid reflux.

Do people gain weight after they stop taking Wegovy?

Yes, a lot of people gain back some of the weight they lost on Wegovy when they stop the medication. This is because your appetite comes back when you stop treatment. It is important to stick to your diet and exercise plan after you stop Wegovy.

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Medically reviewed by:
Dr Babak Ashrafi Clinical Lead for Service Expansion
Accreditations: BSc, MBBS, MRCGP (2008)

Babak studied medicine at King’s College London and graduated in 2003, having also gained a bachelor’s degree in Physiology during his time there. He completed his general practice (GP) training in East London, where he worked for a number of years as a partner at a large inner-city GP practice. He completed the Royal College of GPs membership exam in 2007.

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Last reviewed: 17 Oct 2023





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