In my practice, PMOS, still better known as PCOS, is one of the most commonly misdiagnosed women’s health issues I see. And it goes both ways.
A quick note on the name: in May 2026, PCOS was officially renamed polyendocrine metabolic ovarian syndrome, or PMOS. The new name reflects that it affects your hormones and metabolism, not just your ovaries. You’ll still hear PCOS for a while, so if that’s the name you know, this post is for you. From here on, I’ll use PMOS.
I’ve had women come to me with a PMOS diagnosis, and when I look at their bloods and their symptoms, I’m thinking: you don’t have PMOS. You have none of the signs. Then I’ll have a woman who was told she doesn’t have PMOS, and when we look at the full picture, it really looks like she does.
I find it baffling, honestly. It can feel like whatever is going on with a woman’s cycle, PMOS is the front runner. And very often the next step is the pill.
The pill can be the right choice for some women, and that’s always your decision to make. But it’s worth knowing what it’s actually doing.
The bleed you get on the pill isn’t a true period. It’s a withdrawal bleed, caused by the break in hormones. So when women are told the pill is “regulating your cycle,” that isn’t quite what’s happening. It’s switching your own cycle off and replacing it. Whatever was behind your irregular periods in the first place is still there, just hidden. That’s often why symptoms come back, sometimes stronger, when women come off it.
I believe your cycle is like a monthly report card. When it’s irregular, it’s telling you something. I’d always rather we find out what.
This isn’t just about getting the name right. A PMOS diagnosis comes with a very specific set of advice, and the main one is: cut your carbs. That’s because the most common type of PMOS is driven by insulin resistance.
But what if it isn’t PMOS?
One of the conditions I see mistaken for PMOS most often is hypothalamic amenorrhea. That’s when your periods stop, or become very irregular, because your brain has turned down the signals to your ovaries. It’s usually a response to stress on the body: not eating enough, not eating enough carbs, a lot of high-intensity exercise, or a life that’s simply running too fast for too long.
And the advice for hypothalamic amenorrhea is almost the complete opposite of PMOS advice. It’s about eating enough, making sure you’re having carbs, easing off intense exercise and bringing your stress down. So a woman with hypothalamic amenorrhea who’s been told she has PMOS, and starts cutting carbs and pushing harder at the gym, can end up moving further away from getting her period back.
I’ve caught this numerous times in clinic, just by looking at bloods properly.
I want to say this clearly: I never give out about GPs. It isn’t their fault. They have very little time with each person, and unless they have a special interest in women’s health, the finer detail of what these hormone levels mean isn’t always their focus.
That’s where I can help. When a woman comes to me with irregular cycles, I look at her bloods and her symptoms together. If you’d like to ask your GP for a fuller picture, these are the tests worth requesting:
Thyroid and prolactin are in there because both can cause irregular periods on their own, and they need to be ruled out before anyone settles on PMOS.
Very low LH and FSH, for example, point more towards hypothalamic amenorrhea than PMOS. It’s patterns like this that tell us what’s really going on.
One thing I see missed again and again is DHEAS. It often isn’t checked at all. And when it is, it can come back “within range” when, for that woman and her symptoms, it isn’t where it should be.
In my practice it’s quite common to find raised DHEAS sitting behind acne (often along the jawline), facial hair, thinning hair on the head, and other androgen-type symptoms. If no one has looked at it, those symptoms can stay a mystery for years.
When it really is PMOS, the picture I usually see is:
Not everyone will have facial hair or acne, but they’re common.
PMOS isn’t one condition with one cause. In my practice, and in Lara Briden’s work, whose writing and research I draw on a lot, there are four main types:
Knowing which type you have changes everything about what will help.
There’s no one-size-fits-all plan, and we start with your foundations and build from there, so it isn’t a shock to the system. Depending on what’s driving your PMOS, the foundations usually include:
Reducing carbs can help some women with insulin-resistant PMOS. But I never cut them out completely. Women need carbohydrates for their hormones to stay balanced, and going too low can create a whole new set of problems.
A note on how I work: real change doesn’t happen overnight. We start with your foundations and build from there, and there’s always more we can do as your body responds. Anything hormonal takes at least three months to shift (it takes around three months for a follicle to mature), so the real difference comes from consistency: sticking with the changes, giving your body time on the plan (your food, your lifestyle, and herbs or supplements where they’re needed), and being patient with yourself. There’s no magic pill that will fix everything at once.
If you’ve been told you have PMOS and it’s never quite made sense, or you’ve been told you don’t but your body is saying otherwise, I’d love to help you get to the bottom of it. We’ll look at your bloods, your symptoms and your cycle together, and build a plan that fits your life.
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I'm a nutritionist and registered herbalist, and I help women get to the bottom of what's going on with their hormones: painful or irregular periods, PCOS, endometriosis, coming off the pill, fertility and perimenopause. I also support mams through the postpartum years, when so much of the care stops. I work online with women across Ireland and beyond. Slowly, gently and bit by bit, so the changes actually last.
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