Can Mounjaro affect your periods?

Mounjaro was supposed to change your weight, not your periods too! This wasn’t a 2 for 1 deal! So what gives? Let’s unpack the menstrual mysteries between Mounjaro and periods.

First, what is Mounjaro?

Mounjaro (or medically known as tirzepatide) is a weekly injection designed to treat type 2 diabetes, and help with weight loss. It works by mimicking some of your gut hormones that curb appetite and regulate your blood sugar levels. So you’re eating less and losing weight. 

Is there a link between weight loss and period changes? 

Yes, it’s all connected, in a strange and not-so mysterious way! There is a strong, evidence-based link between weight changes and your menstrual cycle. The key player in this is the hypothalamic-pituitary-ovarian (HPO) axis, which describes the cascade of hormones from your brain to your ovaries that controls the menstrual cycle. The HPO axis regulates the production of your reproductive hormones and it is very sensitive to any big or sometimes small shifts in body fat¹. 

Our body fat is a major source of oestrogen production. When you lose body fat rapidly, through calorie restriction or weight loss medications, your oestrogen levels may fall. This disrupts ovulation and can lead to changes in your menstrual cycle. 

In people who are underweight or have lost a significant amount of weight quickly, your body suppresses your reproductive hormones leading to hypothalamic amenorrhea (absent periods). This is a protective mechanism, probably through evolution, that meant we didn’t getting pregnant with new babies in times of famine or stress. For those struggling with obesity or polycystic ovarian syndrome (PCOS), losing weight can improve insulin sensitivity and restore your menstrual cycles, leading to more regular periods². 

Can Mounjaro affect your periods? 

Mounjaro isn’t directly trying to cause period drama. But by helping you lose weight, it has an indirect effect on your reproductive hormones and shakes up your menstrual cycle. Some people might notice more regular or irregular cycles, changes to their flow or stronger cramps. This is just your cycle’s way of adjusting to your new weight, and think of it as a temporary shake up. However, if your body has been missing its period or you develop changes like heavy periods or bleeding in between periods or after sex for more than 3 months, speak to your doctor!

A survey done by Natural Cycles of 1754 users looking into Mounjaro and period changes found some interesting results. Of all respondents, 45% experienced more predictable periods, 21% noticed more frequent periods and 19% had shorter periods. In women with PCOS, 64% experienced more predictable periods, 23% noticed more frequent periods and 20% had shorter periods⁵. 

Can Mounjaro stop or delay periods?

Wondering why your period is showing up fashionably late, or taking her own sweet time? It is likely due to the weight loss – shock! The disruption of your HPO axis can temporarily halt ovulation and can cause delayed or even missed periods. This is called hypothalamic amenorrhea. This is when the disruption to your menstrual cycle is specifically due to issues with the hypothalamus, a part of the brain that regulates hormone production. 

Think of it this way, if you’ve lost too much weight your body goes into survival mode and shuts down your HPO axis. Why, because it doesn’t think it can support a pregnancy!

If you’ve been googling can Mounjaro stop periods for more than 3 cycles, it is best to book an appointment with your GP pronto!

Can Mounjaro make periods heavier and painful?

I’ve searched and sourced the internet but the research is questionable around how GLP-1 agonists like Mounjaro can cause heavy periods or painful periods. You’ll find streams of entries on Reddit talking about how their periods are running amok. One of the tales tells a story about how this might be due to the ‘oestrogen surge’ experienced due to sudden weight loss. Medically, this theory isn’t founded.

Though interestingly, I found a case study where a woman with severe period pains that were resistant to standard treatments found real relief in her symptoms after starting Mounjaro. Researchers think this could be down to the anti-inflammatory and anti-oestrogenic effects that can help dial down the pain levels. Let’s not get too excited, for now it’s just the one case but it opens the door to the idea that GLP-1 medications like Mounjaro might work outside weight loss or diabetic management. 

We’ve actually taken a deep dive into how Mounjaro might do more than just mess with your period, it could potentially help ease painful periods, especially in conditions like endometriosis, thanks to its anti-inflammatory powers.

What else can Mounjaro do?

What about Mounjaro and spotting? Well anything COULD happen really. It is not exactly researched but with your hormones going on a roller coaster ride, your body could react in any way it wants. If you are spotting with Mounjaro on HRT, you must see your doctor. And any spotting for 3 months or more, should be checked out.

There is still so much we don’t know about the human body – especially the female body! But once we know more, I promise we’ll get back to you! If you don’t want to miss out on the latest women’s health research, sign up to our newsletter!

Final thoughts

Period changes are technically not listed on the side effect sheet of Mounjaro, though there are many women who have found it messing with their periods. The research into Mounjaro and menstrual health is still a little thin, but the theory lies behind the HPO axis. 

Users of Mounjaro can experience no-show cycles, constant spotting or unbearable cramps. If it’s causing a little too much chaos in your life, please talk to your Mounjaro provider. Until then, keep track of these changes and any other side effects you might be having.