Vomiting is a common side effect of weight loss medications, affecting more than 1 in 10 people taking Mounjaro® or Wegovy®. You are most likely to experience this when you first start your treatment or when you increase your dose.
Use this guide to:
Learn how to manage nausea and vomiting at home.
Understand the updated guidance regarding oral contraception.
Identify when you need to seek urgent medical attention.
How to Manage Vomiting
While your body adjusts to Mounjaro® or Wegovy®, you can use the following strategies to manage symptoms and stay nourished:
Prioritise hydration: Take small, frequent sips of water to avoid dehydration. Herbal teas, such as ginger or peppermint, can also help settle the stomach.
Eat bland foods: Stick to a simple diet that is easy on the digestive system, such as toast, rice, and bananas.
Eat small, frequent meals: Rather than eating large amounts at once, try small portions throughout the day to maintain your energy levels.
Important Guidance: Weight Loss Medication and Contraception
Recent medical guidance highlights that weight loss injectables can impact the effectiveness of oral contraceptive pills due to the way they slow down gastric emptying.
Tirzepatide (Mounjaro®)
Clinical evidence suggests that Mounjaro® may reduce the absorption of oral contraceptive pills. To ensure you remain protected against pregnancy, you should:
Use barrier methods: Use a barrier method of contraception (such as condoms) in addition to your pill for four weeks after starting the medication and for four weeks after every dose increase.
Consider non-oral options: Alternatively, you may wish to discuss switching to a non-oral form of contraception (such as the coil, implant, or patch) with your GP, as these are not affected by weight loss injectables.
Semaglutide (Wegovy®)
Currently, there is no evidence that semaglutide reduces the effectiveness of the oral contraceptive pill. However, for all patients using GLP-1 medications, effective contraception is essential, as these drugs are not recommended during pregnancy.
If You Experience Vomiting or Diarrhoea
Vomiting or severe diarrhoea can interfere with the absorption of any oral medication, including the contraceptive pill.
If you vomit within three hours of taking your pill, or if you experience severe diarrhoea for more than 24 hours, the medication may not have been fully absorbed.
In these instances, you should follow the standard guidance for a "missed pill" and use additional barrier protection (such as condoms) until your symptoms resolve.
When to Contact Your GP or Call 111
Contact a healthcare professional if you experience any of the following:
You have been vomiting for more than two days.
You show signs of dehydration, such as passing dark urine or urinating less frequently than usual.
(Always inform the healthcare provider that you are taking weight loss medication.)
When to Seek Urgent Medical Help
Call 999 or go to your nearest A&E immediately if your vomiting is accompanied by any of the following:
Your vomit contains blood or looks like coffee granules.
You are vomiting three or more episodes per day.
You have a high fever or chills alongside the vomiting.
You experience sudden or severe stomach pain.
Additional Resources
For further information on managing side effects and general guidance on GLP-1 weight loss treatments, visit our Weight Loss Health Guide.
If you still need help after reviewing the information above, additional assistance is available from the MedExpress team.