Written and medically assessed by W. van Donselaar, MD, BIG 79020681301, on 10-06-2026.
Saxenda often causes side effects, especially in the first few weeks. Most are mild and go away by themselves. Complaints to your stomach and intestines top the list. A small group keeps suffering for longer. An even smaller group gets a rare, serious side effect requiring prompt medical attention. Which complaints there are, how often they occur, what you can do about them yourself and when to call your doctor: you can read all about it below.
What side effects occur?
The package leaflet classifies side effects by how often they occur. For Saxenda, this looks as follows:
| How often | Update |
|---|---|
| Very often (more than 1 in 10) | Nausea, diarrhoea, vomiting, constipation |
| Frequent (1 in 100 to 1 in 10) | Headache, fatigue, dizziness, abdominal pain, heartburn, burping, dry mouth, low blood sugar when combined with other blood sugar reducers |
| Sometimes (1 in 1,000 to 1 in 100) | Inflammation of the pancreas, gallstones, kidney complaints, accelerated heart rate |
| Rarely | Severe allergic reaction |
Why exactly stomach and intestines?
Liraglutide, the active ingredient in Saxenda, slows down gastric emptying. Your food stays in your stomach longer. This helps you feel full faster, but it can also induce nausea and abdominal pain. You especially notice this with large or fatty meals.
In the build-up phase, your body is not yet used to that new rhythm. This is why symptoms are strongest in the first weeks. And again when the dose goes up. For most people, the symptoms diminish within two to four weeks on a stable dose.
Saxenda is therefore a daily injection with a gentle build-up schedule. You start at 0.6 mg a day and go up in steps to 3.0 mg. Each step takes at least a week. Increasing too quickly is more likely to cause symptoms without allowing your tolerance to grow.
What can you do yourself?
A few practical adjustments help a lot:
- 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, even if your plate is not yet empty.
- Drink small sips of water, spread throughout the day.
- Take a short walk after dinner.
Specifically for nausea, ginger tea, dry crackers and light meals work well. Avoid alcohol in the build-up phase; it intensifies symptoms.
In case of persistent diarrhoea, drink plenty and eat easily digestible food (rice, banana, toasted bread). Leave dairy and highly spiced food for one to two days. For constipation, fibre, water and regular exercise help. Does a complaint persist for more than two to three days, or do you feel really bad? If so, call your doctor or counselling on your course.
Considering the medical way to lose weight? Schedule a no-obligation consultation at WeightConsult. Do our own health check. Do you know if you qualify? Then fill in the simple questionnaire right away to start the process.
When do you call your doctor?
Most side effects are annoying but not dangerous. In case of these signs, do call your doctor or the GP station immediately:
- Persistent, severe abdominal pain, possibly radiating to your back. This may indicate inflammation of the pancreas.
- Signs of gallstones: severe pain in the upper right of your abdomen, especially after eating fatty foods, sometimes with yellowing of skin or eyes.
- Signs of a severe allergic reaction: swelling of face, lips, tongue or throat, difficulty breathing, severe rash.
- Signs of dehydration due to persistent vomiting or diarrhoea: little urination, dry mouth, dizzy when standing up.
When in doubt: better to call than escalate a complaint.
When combined with other medications
Saxenda together with other agents changes the side-effect profile. Two combinations require extra attention. With insulin or other blood sugar-lowering drugs, the risk of low blood sugar (hypoglycaemia) increases. Your doctor then often lowers the dose of the other drug. Never adjust your insulin yourself when starting Saxenda. With drugs that work on your kidneys or withdraw fluid, your doctor will check your kidney function extra, especially if you lose a lot of weight.
During an intake, we map out all your medication and assess where adjustment or additional monitoring is needed. Do you use oral contraception? Due to slower gastric emptying, intake may change slightly, although this is rarely clinically relevant.
Do the check If you want to know whether a guided path suits you and how we monitor 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 stressful. In clinical trials, some of the participants stop early, often because of side effects or insufficient response.
A few questions will help with that consideration.
- On a scale of one to 10, how severe are your symptoms?
- How much hindrance do you experience in your daily life?
- What alternatives have not yet been tried, such as a lower dose, a slower build-up or a different drug?
- And which lifestyle changes do you already support, and which ones not yet?
In a course, we discuss this at the evaluation moments. Those with persistent excessive symptoms discuss options with the doctor. A lower maintenance dose may help, e.g. 2.4 mg instead of 3.0 mg, or switching to another drug.
For product information such as composition, contraindications and storage see the Saxenda medication review. For a guided route with Saxenda injections where monitoring for side effects comes along by default, you can fill in the questionnaire If you qualify.
Key points blog
How common are side effects of Saxenda?
How common are side effects of Saxenda?
Gastrointestinal complaints are the most common. Nausea, diarrhoea, vomiting and constipation are very common: in more than one in 10 users, according to the package leaflet. They occur mainly in the first two to four weeks and around each dose increase.
When should I worry?
When should I worry?
In case of severe persistent abdominal pain, continued vomiting, swelling of the face or tongue, or signs of dehydration. 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 maintenance dose may help.