When Weight Loss Medication Meets Hormones: What You Need to Know About Contraception and Hormone Replacement Therapy (HRT)
If you’re taking an incretin-based weight loss medication AKA GLP-1 agonist (GLP-1) e.g. Wegovy (semaglutide) or Mounjaro (tirzepatide) and you’re also using oral contraception or oral HRT, there’s some important information you need to know.
These medications can affect the way your body absorbs hormones taken by mouth. This means if you take oral hormonal contraception or oral HRT you might not be getting the protection or balance you expect - especially when your dose of weight loss medication is increased.
Let’s break down what that means and what to do about it.
Why dose changes matter
GLP-1s slow down how quickly your stomach empties (gastric emptying). This helps you feel full for longer, but it also means that anything taken by mouth — like an oral contraceptive or oral HRT — can take longer to absorb, or sometimes not fully absorb.
Current evidence suggests the impact of delayed gastric emptying is of greater importance if you are taking Mounjaro and more significantly when you start Mounjaro or your dose is changed or increased.
If you take oral contraception and Mounjaro
If you use the combined oral contraceptive pill or the progestogen-only pill, you’ll need to take extra precautions on starting Mounjaro and each time your dose of Mounjaro increases.
This advice does not apply to Wegovy based on current evidence.
The guidance is:
Use a barrier method of contraception (such as condoms) in addition to your pill for 4 weeks after starting Mounjaro, and for 4 weeks after any dose increase. Alternatively, talk to your healthcare provider about switching to a non-oral form of contraception — such as a hormonal implant, intrauterine device (IUD), injection, vaginal ring, transdermal patch, or copper IUD — which aren’t affected by how your stomach absorbs medication.
Diarrhoea and vomiting are common side effects of GLP-1 agonists and can also reduce the effectiveness of any oral contraceptive. If vomiting occurs within three hours of taking your contraceptive pill, or severe vomiting occurs for more than 24 hours you should follow the advice in the information leaflet in your contraceptive packet, speak to your GLP-1 prescriber or a healthcare professional such as a pharmacist, nurse or doctor or contact for advice.
This isn’t about making life complicated; it’s about making sure you stay protected throughout your weight loss journey.
If you are taking oral HRT during the menopause transition AKA perimenopause and a GLP-1 agonist Mounjaro OR Wegovy
A higher body weight and taking oral HRT can increase your risk of a blood clot (venous thromboembolism (VTE)), transdermal delivery of oestrogen (gel, patch or spray) is preferable as are neutral to VTE risk. This advice is also the case taking a GLP-1.
If you take oral progestogen (as part of HRT)
If you’re on HRT that includes oral progestogen, either synthetic or “body-identical” e.g. micronised progesterone, you’ll need to be a bit more cautious at initiation of a GLP-1 and during dose adjustments too. Progestogen is an essential hormone for all women taking HRT with a uterus (womb) to prevent thickening of its lining (endometrium). If the uterine lining becomes too thick there is an increased risk of endometrial hyperplasia and uterine (endometrial) cancer. Taking progestogen counteracts the growth-promoting effect of oestrogen on the uterine lining.
From a pragmatic perspective a non-oral route for the progestogen component of HRT in women with a uterus would be preferable whilst taking a GLP1-agonist. Transdermal patches or an intrauterine device (IUD) containing 52mg levonorgestrel such as Mirena, Levosert, or Benilexa — can be good alternatives, as they’re unaffected by the way GLP-1 agonists work in your gut and can also provide contraception during the perimenopause.
Current advice is for 4 weeks after initiation and for 4 weeks after each GLP-1 dose increase to double your oral progestogen dose until a stable dose is achieved.
It’s not just about contraception
Even if you’re taking HRT for symptom management during the perimenopause or menopause transition rather than contraception, reduced absorption can still leave you with fluctuating hormone levels. You may notice a temporary return of hot flushes, sleep disruption, or mood changes after a GLP-1 dose increase. If that happens, don’t panic — speak to your healthcare provider. A short-term adjustment to your HRT or a switch to a non-oral route usually resolves the issue.
The bottom line
GLP-1 medications can make a huge difference to your health and well-being, but it’s important to be aware of how they interact with other treatments — especially hormones taken by mouth.
If you’re using oral contraception or oral HRT:
Use barrier protection for 4 weeks after initiation and for 4 weeks after each GLP-1 dose increase, or
Switch to a non-oral method for steady protection and peace of mind.
Always talk through your options with your healthcare provider. With a bit of planning, you can stay protected, stay balanced — and stay on track with your weight-loss journey.
This is for informational purposes only. For medical advice pertaining to your personal treatment please consult your Mova Medical Professional.
Always follow the instructions that come with your medication and if in any doubt about your treatment contact Mova Medical Immediately.