Written and medically assessed by W. van Donselaar, MD, BIG 79020681301, on 20-05-2026.
Ozempic has side effects, mainly gastrointestinal. Most are mild to moderate and occur in the first few weeks, when your body needs to get used to semaglutide. What proportion of users experience them depends on dosage, build-up phase and individual factors. Which side effects are common, how to manage them and when to call your doctor: we cover that below.
Which side effects are most common?
The package leaflet classifies side effects by how often they occur. For Ozempic we see the following picture:
| Frequency | Update |
|---|---|
| Very often (>1 in 10) | Miscommunication, diarrhoea, vomiting, , abdominal pain |
| Frequent (1 in 100 to 1 in 10) | Fatigue, headache, dizziness, gastroenteritis, heartburn, burping, low blood sugar when combined with other agents |
| Sometimes (1 in 1,000 to 1 in 100) | Inflammation of the pancreas, gallstones, kidney complaints, faster heart rate |
| Rarely | Severe allergic reaction |
| Very rarely | An eye disease (NAION) in recent reports; link still under investigation |
Gastrointestinal complaints are thus the most common. Nausea tops the list. In studies, about four in 10 people suffered from it in the build-up phase. The rest did not, or in milder form.
Why are gastrointestinal complaints so common?
Semaglutide makes your stomach empty more slowly. This helps you feel full. But it can also cause nausea and abdominal pain, especially with large or fatty meals. Your body has to get used to this new rhythm. That's why the symptoms are strongest in the first few weeks. And again when the dose goes up.
In most people, symptoms subside within two to four weeks. This is precisely why the dose goes up slowly: first 0.25 mg, then 0.5 mg, and only later higher. If you go too fast, you get more trouble.
An example. A 43-year-old woman had nausea and mild headaches for the first 10 days. Around week three, these were gone. When switching to 0.5 mg, nausea returned briefly, for a week. No serious symptoms. After that, the course continued steadily. Whether your body reacts in this way cannot be predicted. But we see this pattern more often.
What can you do yourself?
A few things help keep symptoms bearable:
- Eat smaller portions, more often a day.
- Avoid fatty, heavy or highly spiced meals in the first weeks.
- Stop eating as soon as you feel full.
- Drink small sips of water, spread throughout the day.
- Take a short walk after dinner.
For nausea, ginger tea, dry crackers and light meals work well. Don't drink alcohol in the build-up phase: it makes nausea worse. For diarrhoea, eat light meals (rice, banana, toasted bread) and drink plenty. For constipation, fibre, water and exercise help. Does a complaint persist for more than two to three days? Then call your doctor.
When do you call your doctor?
Most symptoms are annoying but not dangerous. In case of these signs, though, call your doctor or the GP station immediately:
- Severe, persistent abdominal pain, sometimes to your back. This may indicate inflammation of the pancreas.
- Signs of gallstones: severe pain in the upper right side of your abdomen, especially after fatty foods, sometimes with yellow skin or eyes.
- Suddenly seeing worse, especially with diabetes.
- Severe allergic reaction: swelling of the face, lips, tongue or throat, or difficulty breathing.
- Signs of dehydration: little urination, dry mouth, dizzy when standing up.
In doubt about a complaint? Then call anyway. Better to call once too many than let a serious side effect continue.
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Side effects with other drugs added
Combine your Ozempic injections by other means, then the picture changes. Two combinations require attention:
- With insulin or certain blood sugar reducers: the risk of low blood sugar increases. Your doctor will then often lower the dose of the other drug. Never adjust that yourself.
- With drugs that work on your kidneys: your kidney function will be checked extra, especially if you have lost a lot of weight.
At an intake, we chart all your medications. Do you use the pill? The slower stomach sometimes changes the absorption slightly, although this is rarely significant.
Do the check If you want to know if a supervised pathway suits you and how we follow the first weeks together.
Do the side effects outweigh the effect?
For most people, yes, if the symptoms subside after a few weeks and the effect sets in. For a small group, the symptoms remain too severe. In studies, about one in four people stop early, often due to side effects or too little effect.
A few questions to help with that consideration:
- How bad are your symptoms, on a scale of 1 to 10?
- How much do you suffer in your daily life?
- What hasn't been tried yet: a lower dose, building up more slowly, another drug such as Mounjaro?
- Which lifestyle changes do you already support, and which ones do you not yet?
You discuss this at the evaluation moments. Often the side effects have peaked after a few weeks. If someone keeps suffering too much, a lower dose or another drug may help. Read more about the duration in how long have you been using Ozempic.
Key points blog at a glance
How common are side effects?
How common are side effects?
Gastrointestinal complaints are the most common. Nausea, diarrhoea and constipation are very common: in more than one in 10 users. Especially in the first two to four weeks and after a higher dose.
When should I worry?
When should I worry?
In case of severe persistent abdominal pain, continued vomiting, swelling of the face or tongue, or sudden worsening of vision. If so, call your doctor or the GP surgery immediately. These symptoms are rare but deserve prompt help.
Do side effects disappear on their own?
Do side effects disappear on their own?
Usually yes, within two to four weeks, as your body gets used to it. After each higher dose, there may be another mild round, even temporarily. Does it persist? Discuss it with your doctor. Building up more slowly or a lower dose may help.