Mounjaro (tirzepatide) is a prescription only medicine given as a once weekly pre filled pen, not a tablet. In the UK, it is licensed for weight management in eligible adults and for the treatment of type 2 diabetes in appropriate patients . Like any prescription medicine, Mounjaro can cause side effects, and two topics people commonly search for are changes in taste and its effect on hormonal contraception. This guide explains both, along with common gastrointestinal side effects and when to speak to a healthcare professional.
Does Mounjaro Affect Birth Control?
This is an important question for anyone using hormonal contraception alongside Mounjaro. Unlike general advice about illness affecting the contraceptive pill, Mounjaro has a specific interaction that is explained in its product information.
Mounjaro (tirzepatide) works partly by slowing down gastric emptying, which means food and medicines move through the stomach more slowly. This may affect the absorption of oral hormonal contraceptives, including the combined pill and progestogen only pill . This effect can happen even if you do not experience vomiting or diarrhoea.
The effect is considered most relevant when starting Mounjaro and after each dose increase, and it may reduce over time as your body adjusts to treatment.
If you take an oral hormonal contraceptive and are starting Mounjaro or increasing your dose, current product guidance advises using an additional barrier method of contraception, such as condoms, or considering a non oral contraceptive method for 4 weeks after starting treatment and for 4 weeks after each dose increase .
Contraceptive methods that are not taken by mouth, such as the intrauterine device (coil), contraceptive implant, contraceptive injection, contraceptive patch and vaginal ring, are not affected by this specific interaction because they do not rely on absorption through the digestive system in the same way.
It is also important to remember that general missed pill guidance still applies. If you experience vomiting or severe diarrhoea while taking an oral contraceptive, follow the advice in your contraceptive leaflet, as this is separate from the Mounjaro specific interaction.
If you are using or considering using an oral contraceptive while taking Mounjaro, discuss this during your clinical assessment and check the latest patient information leaflet for both medicines, as guidance can change over time.
Planning Pregnancy or Emergency Contraception While on Mounjaro
Mounjaro is not recommended during pregnancy unless specifically advised by a healthcare professional . If you are planning to try for a baby, speak to your prescriber before stopping treatment so they can advise you on the right approach for your circumstances.
If you become pregnant while taking Mounjaro, contact your GP or prescriber for advice.
There is limited information available on how medicines such as tirzepatide may affect emergency contraceptive pills. If you need emergency contraception while taking Mounjaro, tell the pharmacist or healthcare professional that you are using tirzepatide so they can recommend the most suitable option for you.
A copper intrauterine device (IUD), where suitable, is not affected by the same gastric emptying mechanism and is one recognised option for emergency contraception . However, the best choice depends on your individual circumstances and should be discussed with a healthcare professional.
Does Mounjaro Affect Hormone Replacement Therapy (HRT)?
If you use oral HRT alongside Mounjaro, speak to your healthcare provider for advice. Since Mounjaro can slow gastric emptying, it may affect how some medicines taken by mouth are absorbed .
The specific evidence and guidance around HRT is less established compared with oral contraceptives, so it is important to mention any oral HRT during your clinical assessment.
Non oral HRT options, such as patches or gels, do not rely on absorption through the digestive system in the same way.
Does Mounjaro Cause a Bad Taste in the Mouth?
Some people taking Mounjaro report changes in taste, which may include a metallic, bitter, sour or unusual taste sensation. Taste disturbance (dysgeusia) has been reported with Mounjaro, although the frequency and likelihood can vary between sources . For the most up to date information, check the patient information leaflet supplied with your medicine or speak to your pharmacist.
The exact reason why some people experience taste changes while taking Mounjaro is not fully understood. Possible contributing factors may include changes in digestion, slower stomach emptying, acid reflux, or nausea, which can affect how food and flavours are experienced.
If you notice a persistent or bothersome change in taste, mention it to your healthcare provider, especially if it is affecting your ability to eat or your daily routine.
Managing taste changes:
- Maintain good oral hygiene. If you experience dry mouth, reduced saliva production can make unusual tastes more noticeable.
- Stay well hydrated, as dehydration can reduce saliva flow and may make taste changes more noticeable.
- Chew sugar free gum to help increase saliva production and reduce an unpleasant taste.
- Choose mild, plain foods if strongly flavoured or spicy foods feel less enjoyable while your taste is affected. Eating smaller meals may also help if reflux appears to trigger the taste changes. Avoid lying down soon after eating.
- If taste changes continue beyond the first few weeks, become worse after a dose increase, or start affecting your ability to eat and drink enough, speak to your prescriber or pharmacist for advice.
- If taste changes are accompanied by mouth pain, swelling, or ulcers that last more than a couple of weeks, speak to a healthcare professional or dentist rather than trying to manage it yourself.
Taste and smell are closely connected, so some people may notice changes in both. However, altered taste (dysgeusia) and altered smell are different experiences, even though they can sometimes happen together.
Does Mounjaro Make Food Taste Different, and What About Smell Sensitivity?
Some people notice broader changes in how food tastes while taking Mounjaro, beyond a specific metallic or unusual taste. You may find that certain foods you previously enjoyed taste different, seem less appealing, or that some flavours feel stronger or weaker than before.
Changes in digestion, appetite, and eating patterns may affect how certain foods are experienced. For example, some people notice that richer or fatty foods taste different while taking Mounjaro. Some people also report changes in smell sensitivity, although altered smell and altered taste are separate experiences even though they can happen together.
If changes in taste or smell are affecting how much you eat or drink, mention this during a follow up consultation or speak to your prescriber. A change in food preferences is not always a concern, as Mounjaro may help reduce appetite and support smaller portion sizes for some people . However, there is a difference between eating less because you feel fuller and eating less because food tastes unpleasant. Persistent taste changes that affect your nutrition are worth discussing with a healthcare professional.
Mounjaro's Common Gastrointestinal Side Effects
The most commonly reported side effects of Mounjaro affect the digestive system. According to the UK product information, these can include nausea, diarrhoea, vomiting and constipation .
These side effects are usually mild to moderate and are reported more often when starting treatment or increasing the dose. For many people, digestive symptoms improve as the body adjusts to the medicine over time .
If side effects are severe, persistent, or affecting your ability to eat, drink, or continue treatment comfortably, speak to your prescriber or pharmacist for advice. Your healthcare provider can help you understand whether any changes to your treatment plan may be needed.
| Managing common GI side effects | Approach |
|---|---|
| Nausea | Smaller, more frequent meals, dietary adjustments such as avoiding trigger foods; taking fluids between meals rather than with food |
| Reduced appetite | Expected as part of how the medicine works, but monitor for inadequate overall nutrition |
| Diarrhoea or constipation | Stay hydrated, discuss persistent changes with your prescriber |
| Dehydration risk | The product information notes that GI side effects can lead to dehydration, which can affect kidney function, take precautions to maintain fluid intake, particularly if you're older or have existing kidney concerns, and seek advice if you notice reduced urination |
When to Seek Medical Advice
Contact your prescriber or seek medical advice promptly if you experience any symptoms that feel severe, unusual, or concerning, including:
Severe or ongoing vomiting that makes it difficult to keep fluids down, especially if you have signs of dehydration such as reduced urination or feeling unusually weak.
Severe or persistent abdominal pain, particularly if it happens alongside vomiting or fever, as this may need urgent medical assessment.
Signs of an allergic reaction, such as swelling of the face, lips, tongue, or throat, or difficulty breathing. Seek emergency medical help immediately if this happens.
Mouth or tongue symptoms that continue for more than a couple of weeks or do not improve.
Any side effect that is getting worse, feels difficult to manage, or is affecting your daily life.
If a change in taste continues or becomes more noticeable over time, speak to your healthcare professional for advice.
This page provides general information only and is not a replacement for personal medical advice. Your prescriber can advise on whether Mounjaro is suitable for you, how to manage side effects, and any medicine interactions based on your individual circumstances.
