Side effects of Ozempic and Wegovy: what’s common and what should you look out for?

In this guide, we’ll explain how semaglutide works, the common side effects you might notice, and how treatment can be adjusted to improve tolerance and overall experience. We’ll also share how we at Yazen work in a structured way with follow-ups and support, so treatment feels as safe and sustainable as possible.

Why can Ozempic cause side effects?

To understand why side effects can happen, it helps to know how the medicine works. Ozempic and Wegovy contain semaglutide, which mimics a natural hormone in your body called GLP-1. This hormone is released after you eat and helps regulate blood sugar, hunger and fullness.

Semaglutide activates the GLP-1 receptor and strengthens and prolongs your body’s natural signals for fullness and blood sugar control. You feel full sooner, eat less and often notice fewer cravings. At the same time, the speed at which your stomach empties slows down.

Most side effects affect the digestive system, especially at the start of treatment or when the dose is increased. Nausea is the most common. This can happen because:

• Your stomach empties more slowly
  Food stays in your stomach for longer. That can help you feel fuller for longer, but it may also cause nausea, bloating or discomfort.
• Appetite signals in the brain are affected
  The medicine reduces hunger signals. For some people, this change in the body’s signalling can temporarily feel like nausea.

For most people, side effects ease over time as the body adjusts.

How do Ozempic and Wegovy (semaglutide) work?

Semaglutide increases insulin release when blood sugar rises, reduces glucagon secretion and affects appetite regulation in the brain. This leads to increased fullness, lower energy intake and, for many people, clinically meaningful weight loss.

The effect of Ozempic is greatest when treatment is combined with healthy eating habits and regular physical activity, based on advice from your doctor or dietitian.

Ozempic, developed by Novo Nordisk, is licensed in the UK for adults with insufficiently controlled type 2 diabetes, alongside diet and exercise.

Wegovy contains the same active ingredient, semaglutide, but is licensed specifically for weight management in adults living with obesity, or overweight with at least one weight-related health condition. The main difference between Ozempic and Wegovy is their licensed use and dosing schedule.

Common side effects of Ozempic and other GLP-1 medicines

Most people who experience side effects with GLP-1 medicines notice symptoms from the digestive system. These are usually temporary and tend to happen at the start of treatment or when the dose increases.

Below are the most common symptoms and what may help.

1. Nausea

Nausea is the most common side effect. It happens because the medicine affects appetite regulation and slows stomach emptying. If portions are too large or you eat quickly, discomfort can feel worse.

This may help:

• Reduce fatty and very energy-dense foods, as fat stays in the stomach longer
• Eat slowly and stop before you feel completely full
• Avoid large portions

2. Constipation and wind

Because GLP-1 medicines affect how the gut moves, digestion can slow down and cause more wind. When food moves more slowly through the bowel, more fluid is absorbed, which can lead to harder stools.

This may help:

• Drink enough fluids throughout the day
• Stay physically active. Even regular daily movement helps stimulate the bowel
• Increase fibre gradually to avoid bloating and excess wind
• Try to keep regular meal times

3. Diarrhoea

Some people experience loose stools or diarrhoea at the start of treatment or when the dose increases. This can be linked to how the medicine affects the gut, but also to changes in eating habits. For most, it settles over time.

This may help:

• Choose gentle, easy-to-digest foods for a few days, such as bananas, boiled rice, white bread, pasta or plain fish
• Eat smaller portions that are easier on your stomach
• Drink regularly to replace lost fluids, ideally little and often
• Temporarily avoid coffee, alcohol, dairy, high-fibre foods, fatty or fried foods, and very spicy meals if they make symptoms worse

If diarrhoea is severe, persistent, or combined with fever, dehydration or significant abdominal pain, contact a doctor.

4. Tiredness and headache

Some people feel tired or get headaches at the beginning of treatment. This can be linked to eating less than before or drinking less fluid. Symptoms usually improve as your body adjusts to the new energy balance.

This may help:

• Keep regular meals with nutritious foods, even if portions are smaller
• Make sure you’re drinking enough during the day
• Review your sleep routine and prioritise rest
• Avoid cutting food intake too quickly

If tiredness is severe, ongoing or significantly affecting daily life, speak to your doctor.

Serious but rare side effects

In rare cases, more serious side effects can occur and need medical assessment. They are uncommon, but important to be aware of.

• Gallstones
Rapid weight loss, whatever the method, can increase the risk of gallstones. Symptoms may include sudden and intense pain under the right ribcage, sometimes with nausea or fever. Seek medical advice if this happens.

• Pancreatitis
Cases of acute pancreatitis have been reported with GLP-1 medicines, but they are very rare. Typical symptoms include severe and persistent pain in the upper abdomen, sometimes spreading to the back, often with nausea and vomiting. If pancreatitis is suspected, stop the treatment and seek urgent medical care.

• Allergic reactions
In rare cases, allergic reactions can occur. Symptoms may include swelling of the face, lips or tongue, difficulty breathing or a severe skin reaction. Seek urgent medical help if this happens.

• Low blood sugar
Ozempic and Wegovy on their own rarely cause low blood sugar. The risk increases if they are used together with insulin or sulfonylureas. Symptoms of low blood sugar can include shaking, sweating, palpitations, confusion or difficulty concentrating.

Mild stomach symptoms are common during treatment. But if you have severe and persistent abdominal pain, fever, a marked decline in your general health or severe nausea, seek medical care promptly.

When should you seek medical advice?

If you have questions or concerns about treatment with Ozempic or Wegovy, speak to a healthcare professional. A doctor or nurse can assess your symptoms and make sure your treatment is used safely and correctly.

Even milder side effects should be discussed if they persist or affect daily life. Sometimes the dose needs to be adjusted, increased more slowly, or paused temporarily.

If you’re unsure, it’s always better to check. Treatment should feel safe, and your health always comes first.

How Yazen works to reduce the risk of side effects

Individual treatment and careful follow-up

Treatment with GLP-1 medicines is always tailored to you. A slow dose increase reduces the risk of side effects and improves tolerance over time.

Side effects can temporarily increase when the dose goes up. That’s why dose adjustments are done gradually and under medical supervision.

At Yazen, safety and quality of life are always in focus. Both dosing and follow-up are handled carefully to support the best possible outcome.

The principle of the lowest effective dose

It’s a common myth that you need to reach the maximum dose to see results. In reality, the dose is only increased to the lowest level where reduced hunger and weight loss are achieved. This helps reduce the risk of side effects.

A whole-person approach and everyday support

Medication works best as part of a structured, long-term treatment plan. Regular follow-ups and support help tailor the plan to your needs and life situation. If one type of medication causes too many side effects, alternatives or other strategies can be considered.

Food choices, meal structure and lifestyle habits all influence both tolerance and results. That’s why individual support is a key part of treatment, helping you build sustainable routines and reduce discomfort.

At Yazen, the focus is on safety, quality of life and long-term results, through careful dosing, medical follow-up and continuous support.

Summary

When starting Wegovy or another GLP-1 medicine, treatment should begin in consultation with a doctor and with a clear plan for follow-up and dose increases if needed. Side effects can occur, especially when the dose is increased, which is why adjustments are made gradually under medical supervision. A slower increase reduces the risk of discomfort and improves tolerance over time.

For most people, side effects are mild and temporary. At the same time, the long-term health benefits of treating obesity are well documented, including a reduced risk of type 2 diabetes, cardiovascular disease, and improvements in physical function and quality of life.

At Yazen, the focus is on safety, quality of life and long-term results, supported by careful dosing, medical follow-up and ongoing support.

Sources

European Medicines Agency (EMA) – Ozempic (semaglutide) Prescribing Information
https://www.ema.europa.eu/en/medicines/human/EPAR/ozempic

The New England Journal of Medicine – Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1)
https://www.nejm.org/doi/full/10.1056/NEJMoa2032183

European Medicines Agency (EMA) – Wegovy: European Public Assessment Report (EPAR)
https://www.ema.europa.eu/en/medicines/human/EPAR/wegovy

Postgraduate Medicine. Managing the gastrointestinal side effects of GLP-1 receptor agonists in obesity: recommendations for clinical practice.
https://www.tandfonline.com/doi/full/10.1080/00325481.2021.2002616

Journal of Clinical Medicine. Clinical Recommendations to Manage Gastrointestinal Adverse Events in Patients Treated with GLP-1 Receptor Agonists: A Multidisciplinary Expert Consensus.
https://pmc.ncbi.nlm.nih.gov/articles/PMC9821052/#jcm-12-00145-t002

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