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Semaglutide side effects: what you need to know

A guide to recognizing and managing semaglutide side effects

Semaglutide is the active ingredient in Wegovy and Ozempic.

Keep reading to find out the different possible side effects, how long they usually last, and advice on managing them.

Medically reviewed by Dr. Caroline Fontana Written by our editorial team Last reviewed 30-01-2024

What are the common side effects of semaglutide?

Just like other GLP-1 agonists, the most common side effects of taking semaglutide affect the stomach and digestive tract. More than 1 in 10 people may experience:

Very common side effects
  • feeling sick (nausea)
  • being sick (vomiting)
  • diarrhoea
  • constipation
  • stomach pain
  • feeling tired (fatigue)

In addition to these are some common side effects. These normally affect 1 in 10 people taking semaglutide:

Common side effects
  • feeling dizzy
  • indigestion
  • heartburn (or acid reflux)
  • runny nose and sore throat
  • inflammation of the stomach (gastritis)
  • hair loss
  • gas (flatulence)

Semaglutide and gastritis

Inflammation of the stomach is known as gastritis. It is one of the commonly reported side effects of patients taking Semaglutide:

Signs of gastritis include:

  • abdominal pain
  • nausea
  • vomiting
  • indigestion

You can try taking antacids like Omeprazole or Pantoprazole, as well as tweaking your diet to help improve gastritis symptoms.

Overall, these side effects are completely normal and easy to manage. In the majority of cases, any side effects you initially feel will disappear as your body adjusts to the treatment.

If you’re feeling concerned about managing your side effects, keep reading to find out how you can easily improve your experience on semaglutide.

What are the rare side effects?

It is also important to familiarise yourself with the rare side effects of semaglutide.

Whilst it is unlikely that you will experience them, being able to recognise the symptoms of a serious condition means that you can get medical help more quickly.

The table below outlines the rare conditions that may occur when taking semaglutide:

Rare side effects
  • hypoglycaemia
  • gallbladder problems
  • kidney disease
  • increased heart rate
  • depression
  • pancreatitis


Hypoglycaemia (low blood sugar) is a risk in patients with type 2 diabetes. You may be at an increased risk if you are taking diabetes medication such as sulfonylureas or insulin.

If you experience any of the following, eat something high in sugar and then check your blood sugar in 10-15 minutes:

  • dizziness or light-headedness
  • blurred vision
  • anxiety
  • cold sweating or unusual sweating
  • shakiness
  • weakness
  • confusion
  • slurred speech
  • difficulty concentrating

Being able to recognise the signs of low blood sugar means you can get medical help before your condition becomes critical.

Gallbladder problems

In rare cases, semaglutide can cause gallbladder problems such as gallstones. These can be very painful and sometimes need surgery.

Speak to a healthcare professional if you experience any of the following:

  • severe pain in your upper stomach
  • jaundice (yellowing of the skin and eyes)
  • a high temperature
  • clay-coloured stools

Kidney problems or kidney failure

If you suffer from kidney problems, your condition may worsen due to common side effects such as vomiting and diarrhoea.

Dr. Caroline Fontana

Dr. Caroline Fontana

“Not only will drinking water maintain the function of your kidneys, but it will improve your digestion, brain function, and can help you feel fuller between meals.”

It is important to stay hydrated by drinking plenty of water to avoid possible kidney failure.

Inflammation of the pancreas

Inflammation of the pancreas (pancreatitis) causes severe stomach pain that might reach through to your back.

If you feel persistent abdominal pain, you must stop treatment and seek medical assistance.

Is there a risk of cancer?

In rare circumstances, experts have linked semaglutide to thyroid and pancreatic cancers.

Whilst there hasn’t been conclusive evidence in humans, one study Trusted source European Medicines Agency (EMA) Government Source Medication Regulation and Research (EU) Go to source taken on mice and rats proved semaglutide to have potential thyroid cancer risks.

There is no conclusive evidence for pancreatic cancer from clinical trials, but it is still considered a potential risk, particularly in patients with type 2 diabetes.

Consult your doctor if you experience any of the following:

  • a lump or swelling on the neck
  • hoarseness when speaking
  • trouble swallowing
  • shortness of breath

Do not use semaglutide if you have a family history of thyroid cancer, or if you have a condition called multiple endocrine neoplasia syndrome (MEN 2) which causes tumours on the endocrine glands.

How do I know if I’m having an allergic reaction?

In the rare instance that you are allergic to semaglutide, it’s important to know the signs of an allergic reaction so you know when to seek medical attention.

Any of the following could be an indication of an allergy:

  • a rash
  • itching
  • trouble breathing
  • trouble swallowing
  • swelling of the face, mouth, or throat
  • fainting or feeling dizzy
  • very quick heartbeat

Do not hesitate to call an ambulance if you think you could be suffering from a severe allergic reaction.

How long do side effects last?

Usually, common side effects go away over time as your body adapts to being on semaglutide. This can take anywhere from a few days to a few weeks, depending on the side effects and the individual.

However, they may return when you increase the strength of your dose. Once again, these side effects should be temporary and will clear once your body readjusts to the new dose.

In rarer cases, some side effects might persist for the duration of your treatment.

After finishing treatment, you may need to wait as long as 5 weeks for your side effects to fully clear. However, your body may clear the drug entirely from its system quicker than this.

Speak to your doctor if you are struggling to manage persistent side effects.

How do I manage my side effects?

To manage your initial nausea and other gastric side effects, you can make some small changes to your diet.

By cutting out food groups that are harder to digest, you can reduce your risk of having stomach upset and indigestion. Fatty foods and sugary foods are the worst culprits.

A person declining a burger and chips

When taking semaglutide, it is best to try:

  • eating slowly
  • eating smaller portion sizes
  • sticking to foods that are light and bland
  • drinking ice-cold water or unsweetened tea
  • avoiding greasy, fried, or sugary foods

Some foods that reduce nausea can also be added to your diet. These include:

  • ginger (especially ginger tea)
  • hot broths
  • plain rice or toast
  • peppermint and other herbal tea
  • bananas

Some over-the-counter medications may also help to manage gastric side effects. For acid reflux, you can try taking antacids, and for general nausea, you can try antiemetic tablets.

Always consult your doctor before taking any additional medication during your semaglutide treatment.

Can I reduce my dose to manage side effects?

Reducing your semaglutide dosage is also likely to help manage your side effects.

If you find yourself struggling with side effects after increasing your dose, drop down to the dose below for another 4 weeks.

After this you can attempt to increase the dose once again. If you still find yourself experiencing unmanageable side effects, remain on the lower dose for the duration of your treatment.

Further reading

Hypoglycaemia causes, symptoms and treatment

Semaglutide side effects: what you need to know Hypoglycaemia causes, symptoms and treatment

Reviewed by Dr. Caroline Fontana
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