If you are taking Mounjaro (tirzepatide) and wondering whether what you are feeling could be early pregnancy symptoms, it can be difficult to tell. Nausea, tiredness, changes in appetite and constipation can happen with both Mounjaro and early pregnancy.
The important thing to remember is that symptoms alone cannot confirm pregnancy. If pregnancy is possible, a pregnancy test is the best way to check.
Mounjaro should not be used during pregnancy. The current UK product information says there is limited information about tirzepatide use in pregnant women, and animal studies have shown effects on reproduction. If you become pregnant while taking Mounjaro, stop taking it and speak to your prescriber or GP.
Pregnancy Symptoms vs Mounjaro Side Effects
This is where things can get confusing. Nausea, vomiting, tiredness, changes in appetite and constipation can all occur with Mounjaro, and some of these are also common in early pregnancy.
Feeling sick or having less appetite while taking Mounjaro does not, on its own, tell you whether you are pregnant.
You may notice that some Mounjaro side effects are more noticeable after starting treatment or after a dose increase. However, there is no reliable symptom pattern that can tell you whether nausea is caused by Mounjaro or pregnancy.
A missed period can be a reason to take a pregnancy test, but periods can also be irregular for many reasons. A positive pregnancy test is the clearest way to confirm pregnancy.
Symptom Overlap at a Glance
| Symptom | Can be caused by Mounjaro | Can be early pregnancy | What it tells you |
|---|---|---|---|
| Nausea or vomiting | Yes | Yes | Can happen with both |
| Tiredness | Yes | Yes | Can happen with both |
| Appetite or food changes | Yes | Yes | Can happen with both |
| Food aversions | Possible | Yes | Not enough to confirm pregnancy |
| Constipation | Yes | Yes | Can happen with both |
| Missed period | Not usually a Mounjaro side effect | Yes | A reason to take a pregnancy test |
| Positive pregnancy test | No | Yes | Confirms pregnancy |
Is Breakthrough Hunger a Sign of Pregnancy?
Not necessarily. Changes in appetite can happen for many reasons while taking Mounjaro.
Your appetite may change as your body gets used to the medicine or as your response to a particular dose changes. A missed dose can also affect how you feel.
So, if you suddenly feel hungrier while taking Mounjaro, it does not mean that you are pregnant. If pregnancy is possible, taking a pregnancy test is a much more useful step than trying to interpret a change in appetite.
What to Do If You Think You Might Be Pregnant
If there is a chance you could be pregnant, take a pregnancy test. Home pregnancy tests look for the hormone hCG. Tirzepatide is not known to interfere with hCG testing, so taking Mounjaro should not stop a pregnancy test from detecting pregnancy.
If the test is positive:
- Stop taking Mounjaro. You do not need to taper the dose. Speak to your prescriber about what to do with your next scheduled dose.
- Contact your GP, prescriber or other healthcare professional promptly so they can advise you about your treatment.
- Try not to panic. UKTIS says that the limited available data on GLP 1 medicines do not currently indicate an increased risk of miscarriage, birth defects, stillbirth, low birth weight or premature birth following early pregnancy exposure. However, the available evidence is limited, so this does not mean that tirzepatide has been proven safe during pregnancy.
- If you take Mounjaro for type 2 diabetes, do not leave your diabetes untreated. Your healthcare team can discuss suitable treatment during pregnancy. Metformin and insulin are among the treatments used during pregnancy, depending on the individual situation.
- If you are concerned about medicine exposure during pregnancy, your healthcare professional can advise whether you need any further assessment or monitoring.
How Long to Stop Mounjaro Before Trying to Conceive
If you are planning a pregnancy, the current UK Mounjaro product information recommends stopping tirzepatide at least 1 month before a planned pregnancy.
This is because tirzepatide has a long half life of about 5 days, so it takes several weeks for the medicine to leave the body after the last dose. You do not need to taper Mounjaro before stopping it.
Your prescriber can advise you on when to stop treatment based on your health and treatment plan. If you are planning a pregnancy, it is also a good idea to discuss folic acid and any other medicines you take with your healthcare professional.
Contraception While on Mounjaro
Mounjaro should not be used during pregnancy, so contraception is important if you could become pregnant.
Tirzepatide slows stomach emptying. The current UK product information says that reduced effectiveness of oral contraception cannot be ruled out in women with overweight or obesity. For this reason, it advises switching to a non oral contraceptive method or adding a barrier method, such as condoms, for 4 weeks after starting tirzepatide and for 4 weeks after each dose increase.
This advice is specifically linked to oral contraception in women with overweight or obesity. If you are unsure whether it applies to your contraceptive method, ask your prescriber or pharmacist.
It is also possible to become pregnant even if your periods are irregular. Changes in weight can affect menstrual cycles and ovulation, so an irregular period should not be treated as reliable contraception.
Mounjaro and Wegovy in Pregnancy
The advice is similar for Mounjaro and Wegovy. Neither medicine should be used during pregnancy.
The recommended time to stop them before a planned pregnancy is different:
- Mounjaro (tirzepatide): stop at least 1 month before a planned pregnancy.
- Wegovy (semaglutide): stop at least 2 months before a planned pregnancy.
Semaglutide stays in the body for longer, which is why the recommended gap is longer for Wegovy.
If you are taking either medicine and planning a pregnancy, speak to your prescriber before stopping or changing treatment.
If You Are Already Pregnant
If you have found out that you are pregnant while taking Mounjaro, stop taking it and contact your GP, midwife or prescriber.
Taking Mounjaro before you knew you were pregnant does not automatically mean that something is wrong. UKTIS says that the limited available information on GLP 1 medicines does not currently suggest an increased risk of several adverse pregnancy outcomes following early exposure. However, there is not enough evidence to confirm that these medicines are safe during pregnancy.
Your healthcare professional can look at when you took Mounjaro, your dose and your individual circumstances and advise you about any further care.
If you take Mounjaro for type 2 diabetes, make sure you get advice about alternative treatment because good blood glucose control is important during pregnancy.
A Note on Eligibility
If you are pregnant or planning a pregnancy, Mounjaro is not suitable for use during that time. The current product information recommends stopping tirzepatide at least 1 month before a planned pregnancy.
Breastfeeding is different. The current UK product information says tirzepatide may be considered during breastfeeding based on the available information, although there is still limited evidence. If you are breastfeeding, discuss Mounjaro with your prescriber rather than assuming that it is automatically suitable or unsuitable.
