As with all medicines, taking Saxenda may cause some side effects. Although usually mild and likely to lessen or disappear within two weeks of starting treatment, some can be more severe and could require stopping treatment. You should always read the patient information leaflet fully before you begin treatment.
Some of the most common side effects include:
Please note that you should not drive or operate machinery if you feel unwell from side effects.
If diarrhoea is severe, be mindful that oral contraceptives may not be effective.
If you experience side effects that you’re concerned about, please contact us through your online patient record.
Click below for tips on how to manage some of these side effects.
Nausea and heartburn are common side effects affecting up to 1 in 10 users, and are seen with increasing doses of Saxenda.
An over the counter antacid medicine can also help as your body adjusts to the higher dose. Your Boots or local pharmacist can help you with these.
Constipation is a very common side effect affecting more than 1 in 10 people using Saxenda.
You may wish to try a mild laxative to help, which your Boots or local pharmacist can help you with. Visit the NHS website for more information on dealing with constipation.
Headache is a very common side effect of Saxenda affecting more than 1 in 10 users. This tends to settle within a few days, but may last a few weeks.
If your headache symptoms persist, become worse or you remain worried please contact your GP or NHS 111 for further advice.
More than 1 in 10 people who use Saxenda experience vomiting.
A key to managing this, and most other side effects, is good hydration. Make sure you are drinking plenty of water.
An over the counter antacid medicine can help as your body adjusts to the higher dose. Your Boots or local pharmacist can help you with these.
Vomiting more than 3 times a day may suggest that Saxenda is not suited to you. Please keep an eye on your symptoms.
If your urine turns a dark colour, or you feel light-headed, this may be a sign that you are dehydrated and need to drink more fluids. If this is not possible, or you are becoming more unwell, you need to call NHS 111 for further advice.
This is a very common side effect experienced by more than 1 in 10 people who use Saxenda.
The key thing to managing this is to keep hydrated. Make sure you are drinking plenty of clear fluids (such as water or squash).
If diarrhoea persists over a few days, you are unable to tolerate any fluids, you have bloody diarrhoea or there is bleeding from your bottom, you must call NHS 111 for further advice.
Up to 1 in 10 people who use Saxenda experience injection site reactions. These include redness, bruising, itching, swelling and pain. These tend to settle as your body gets used to the drug. Until then you may wish to try a non-drowsy antihistamine tablet or a local antihistamine cream. Your Boots or local pharmacist can help you with this.
In a few patients redness and itching remains while using Saxenda.
If your rash is getting worse, spreading, becoming more red or the pain is not tolerable please stop using Saxenda and seek further help from your GP, NHS 111 or A & E. Please also let us know this happened via your patient record.
Gallstones are common in the general population, and many people don't even know they have them.
Up to 1 in 10 users of Saxenda develop gallstones, and up to 1 in 100 get an inflamed gallbladder. The main reason for this is rapid weight loss of around 1.5kg (over 3 pounds) a week. It may not be a direct effect of Saxenda.
You can use Saxenda if you are known to have gallstones.
If you develop abdominal pain, especially on the right side under your ribs you must seek medical attention.
If you develop severe pain/ vomiting/ any blood in your urine or a high temperature, please call NHS 111 for advice, or attend A&E. We encourage you to continue to eat small meals throughout the day, so that weight loss doesn’t occur too quickly. Aim to stay well hydrated.
Unpleasant side effects
These usually go away within a few days or weeks. You should stay on your current dose for up to another week before increasing the dose as described in the dosing schedule.
Strong side effects
Drop down to the previous lower dose for up to another 7 days before increasing again.
Please note, if your side effect symptoms persist on the lowest dose, then Saxenda may not be suited to you.
Severe and intolerable side effects
You should immediately stop the medication. If you have very severe abdominal pain contact your GP, NHS 111 or attend A & E as pancreatitis is a rare but serious side effect.
Some people find they can not tolerate Saxenda.
In rare cases, serious side effects may be experienced. You should be aware of these and make sure you stop treatment and seek medical attention.
This is an uncommon but serious side effect. Most patients feel very unwell with it.
If you have severe abdominal pain which might reach through to your back, as well as nausea or vomiting call 111 for advice, or attend A & E.
This is a rare severe allergic reaction. If you have difficulty breathing, or there is swelling of your face, tongue or throat, call 999 or attend A & E.
There have been some theoretical links discussed about using Saxenda and thyroid lumps and cancer. These are based on studies in rodents, but have not been seen in primate or human studies.
A thyroid goitre is a swelling in the thyroid gland. About 15% of the UK population have thyroid goitres or nodules, and the lifetime risk of developing a thyroid nodule is around 5 to 10%.
Saxenda clinical studies showed an increased risk of developing thyroid swellings, like goitres, particularly in patients with pre-existing thyroid disease.
If you have thyroid disease and develop a swelling in your neck or thyroid whilst using Saxenda, you must tell your doctor.
Thyroid cancer is the 20th most common cancer in the UK, accounting for 1% of all new cancer cases. 8% of thyroid cancers are caused by being overweight or obese. Find out more on the Cancer Research UK website.
Saxenda clinical trials carried out on rats and mice showed an increase in thyroid cancer. In particular, this was medullary cancer of the thyroid. This increase was not seen in studies carried out on primates, and importantly has not been seen in human studies of almost 6000 patients.
Pancreatic cancer is the 10th most common cancer in the UK. Almost half of all new cases are diagnosed in people aged 75 and over. A person’s risk of developing cancer depends on many factors. To put this into context, 22% of pancreatic cancers are caused by smoking, and 12% by being overweight or obese. Find out more on the Cancer Research UK website.
Saxenda clinical studies have not shown a link with pancreatic cancer.
We have prepared some answers to the most common questions our patients ask us. If you want to know more about Saxenda, how it works and how to take it, take a look at our Saxenda FAQs.
Page last reviewed by: Dr. Christina Hennessey 20/04/2022