Ozempic can cause side effects, particularly when patients first start treatment or increase their dose. The most common problems include nausea, vomiting, diarrhoea, constipation and bloating. These symptoms often improve over time as the body adjusts to semaglutide, the active ingredient in Ozempic.

However, some side effects can signal more serious complications. Severe abdominal pain, persistent vomiting, yellowing of the skin or eyes, breathing difficulties, dehydration or significant changes in vision require urgent medical attention.

Dr Hussain Ahmad, a UK hospital doctor and consultant practitioner, explained that Ozempic's effects on the digestive system are linked to how the medication works.

'Ozempic commonly causes nausea, vomiting, diarrhoea, constipation and bloating, which can also occur if the dose is increased,' he said. 'These symptoms usually improve over time due to semaglutide slowing stomach emptying and reducing appetite.'

As the use of weight-loss medications continues to rise, understanding the benefits and risks of Ozempic has become increasingly important for patients considering treatment.

What Is Ozempic and Why Is It Prescribed?

Ozempic is a prescription medicine containing semaglutide, a type of medication known as a glucagon-like peptide-1 (GLP-1) receptor agonist.

It is primarily licensed in the UK to help adults with type 2 diabetes manage blood sugar levels. It works by mimicking a hormone naturally produced in the body that helps regulate blood glucose, slows digestion and reduces appetite.

Although semaglutide is also used for weight management under different brand names, Ozempic itself is not a general-purpose slimming drug.

Within the NHS, Ozempic is mainly prescribed for people with type 2 diabetes. For weight loss, semaglutide treatment is available only through specialist weight management services for eligible patients.

'It isn't a standalone slimming drug and works best alongside a healthy diet, regular exercise and medical supervision,' Dr Ahmad said.

Common Ozempic Side Effects

Many people tolerate Ozempic well, but side effects are most likely to appear during the early stages of treatment or after increasing the dose.

Common side effects include:

Nausea

Feeling sick is one of the most frequently reported Ozempic side effects. It happens because semaglutide slows the rate at which food leaves the stomach, which can make people feel fuller for longer.

Eating smaller meals, avoiding rich or fatty foods and staying hydrated may help reduce nausea.

Vomiting

Some patients experience vomiting, particularly after starting Ozempic or moving to a higher dose.

Repeated vomiting can lead to dehydration and may require medical advice, especially if a person cannot keep fluids down.

Diarrhoea

Changes in bowel habits, including diarrhoea, can occur as the digestive system adjusts to the medication.

Patients should drink enough fluids to avoid dehydration.

Constipation

Because Ozempic slows digestion, some people may experience constipation. Increasing fibre intake, drinking water and staying physically active may help.

Bloating and Stomach Discomfort

Feeling bloated, having excess gas or experiencing abdominal discomfort are also possible side effects.

These symptoms are usually temporary but should be discussed with a healthcare professional if they persist or become severe.

Serious Ozempic Side Effects That Need Medical Attention

Severe Abdominal Pain
Stefamerpik via Magnific

Although serious reactions are uncommon, patients should be aware of warning signs.

Severe Abdominal Pain and Pancreatitis Risk

Severe, persistent stomach pain that may spread to the back could indicate pancreatitis, a rare but serious inflammation of the pancreas.

Anyone experiencing this symptom should seek urgent medical advice.

Gallbladder Problems

Some people taking semaglutide may develop gallbladder-related problems, including gallstones.

Symptoms can include:

  • Severe pain in the upper abdomen
  • Fever
  • Nausea or vomiting
  • Yellowing of the skin or eyes

Dr Ahmad advised that 'urgent assessment is required in the event of persistent vomiting, severe abdominal pain, yellowing of the skin or eyes, dehydration, difficulty breathing or major changes in your vision.'

Low Blood Sugar (Hypoglycaemia)

Ozempic alone does not usually cause low blood sugar, but the risk increases when it is taken alongside insulin or medicines called sulphonylureas.

Patients using these medications may need their doses reviewed by their healthcare team.

'Patients taking insulin or sulphonylureas will also need to review their dose due to the risk of hypoglycaemia,' Dr Ahmad said.

Vision Changes

People with diabetes may notice changes in their eyesight when blood sugar levels change rapidly.

Any major or sudden changes in vision should be assessed by a healthcare professional.

Who May Be More Likely To Experience Side Effects?

Some people may have a higher chance of experiencing Ozempic side effects.

Risk factors include:

  • Increasing the dose too quickly
  • Becoming dehydrated
  • Having existing gastrointestinal problems
  • Taking Ozempic alongside certain diabetes medications

Following the prescribed dosing schedule is important. Patients should not increase their dose without medical guidance, even if they feel the medication is not working quickly enough.

Ozempic Interactions: What Should Patients Know?

Before starting Ozempic, patients should tell their doctor or pharmacist about all medicines they take.

Because semaglutide slows stomach emptying, it may affect how quickly some medicines are absorbed.

People using insulin or sulphonylureas may need closer monitoring because of the increased risk of low blood sugar.

Patients should also discuss any history of digestive conditions, pancreatitis or gallbladder problems before treatment.

Common Myths About Ozempic Side Effects

Myth: Ozempic is a quick-fix weight loss injection

Ozempic may reduce appetite and support weight loss in some people, but it is not a replacement for healthy lifestyle changes.

Long-term results usually require changes to diet, activity levels and ongoing medical support.

Myth: Everyone taking Ozempic will experience severe side effects

While digestive symptoms are common, many people experience mild effects that improve as their body adapts.

Serious complications are possible but uncommon.

Myth: You can stop Ozempic suddenly without advice

Patients should speak to their healthcare provider before stopping treatment. Abruptly stopping medication may affect blood sugar control in people with diabetes.

When Should You Seek Urgent Medical Help?

Patients taking Ozempic should seek urgent medical advice if they experience:

  • Severe or persistent abdominal pain
  • Signs of dehydration, such as dizziness or inability to keep fluids down
  • Yellow skin or eyes
  • Difficulty breathing
  • Sudden or significant vision changes
  • Symptoms of a severe allergic reaction

For less severe but ongoing side effects, patients should contact their GP, diabetes team or pharmacist for advice.