PMS: What's Really Causing Your Premenstrual Symptoms

If you spend the week before your period dreading your own body — riding waves of irritability, crying over small things, aching through swollen breasts, or feeling so bloated you can barely button your jeans — you are not alone. PMS is one of the most common health complaints I encounter in my work, affecting anywhere from 30 to 75 percent of menstruating women at some point in their lives.

And yet the response most women receive from their doctors is some version of: "That's just how periods are." Maybe you've been offered the pill to flatten out your cycle, or an antidepressant for the luteal phase, or simply told to take ibuprofen and push through. What you're rarely offered is an explanation of why this is happening — and what you can actually do about it.

PMS is not a character flaw, a side effect of being a woman, or something you have to simply tolerate. It's a sign that something is off hormonally — and once you understand what's driving it, you have real, meaningful options for change.

What PMS Actually Is

Premenstrual syndrome (PMS) is defined as a cluster of physical and emotional symptoms that appear in the luteal phase of the menstrual cycle — the second half, between ovulation and the start of menstruation — and resolve within a few days of bleeding beginning. The pattern is cyclical and predictable: symptoms appear, the period arrives, and then they lift.

That cyclical pattern is the diagnostic clue. It tells us these symptoms are tied to the hormonal events of the luteal phase — specifically, the dramatic fall in estrogen and progesterone that triggers menstruation. When those hormones decline in a disorderly or imbalanced way, the body responds with PMS.

It's also worth distinguishing PMS from PMDD (Premenstrual Dysphoric Disorder), which is a more severe presentation characterised by debilitating mood symptoms — intense depression, rage, or anxiety — that significantly impair daily functioning. PMDD sits at the extreme end of the same hormonal-neurological spectrum, but warrants specific clinical attention. If you're reading this and recognise your experience in that description, please reach out to a qualified healthcare provider.

The Most Common PMS Symptoms

PMS presents differently in different women, but the symptoms cluster into predictable categories that reflect the underlying hormonal and neurological mechanisms at work.

Mood and emotional symptoms

• •Irritability and mood swings — often disproportionate to the situation
• •Anxiety, tension, or a feeling of being on edge
• •Tearfulness or emotional sensitivity
• •Low mood or a flat, depressed feeling
• •Difficulty concentrating or mental fogginess

Physical symptoms

• •Breast tenderness and swelling, sometimes severe enough that wearing a bra is painful
• •Bloating and abdominal distension — often appearing within days of ovulation
• •Fluid retention — puffiness in the hands, face, or legs
• •Headaches or migraines, often timed to the premenstrual estrogen drop
• •Acne or skin breakouts in the week before the period
• •Food cravings — particularly for sugar, refined carbohydrates, and salty foods
• •Fatigue and low energy, even if sleep is adequate

Sleep symptoms

• •Insomnia or disrupted sleep in the luteal phase, particularly waking in the early hours
• •Hypersomnia — excessive sleeping or difficulty getting up in the morning

The Hormone Picture Behind PMS

PMS is fundamentally a luteal phase hormone story. To understand it, we need to understand what's supposed to happen hormonally after ovulation — and what goes wrong in women who experience significant premenstrual symptoms.

The estrogen-progesterone seesaw

After ovulation, progesterone rises sharply. Produced by the corpus luteum — the temporary structure that forms in the ovary after the egg is released — progesterone acts as estrogen's counterbalance. It calms the nervous system via GABA receptor modulation, limits estrogen's proliferative effects on the uterine lining and breasts, has a mild diuretic effect to counter fluid retention, and promotes deep sleep. When progesterone rises sufficiently, the luteal phase can feel relatively stable.

In women with PMS, one or both of the following is occurring: progesterone production is insufficient relative to estrogen (low luteal phase progesterone), or estrogen levels are elevated — creating a relative dominance of estrogen over progesterone. This imbalance, known as estrogen dominance, is the hormonal signature of most PMS presentations.

Serotonin and the mood connection

Progesterone's conversion to allopregnanolone — a potent neurosteroid that activates GABA-A receptors — is a key mechanism behind its calming effect. When progesterone is low, allopregnanolone levels fall, reducing GABA tone and leaving the nervous system more reactive. Simultaneously, declining estrogen in the late luteal phase lowers serotonin availability, contributing to the low mood, cravings, and emotional sensitivity many women experience in the days before their period.

This serotonin connection explains why vitamin B6 — which is a cofactor in serotonin synthesis — is one of the most evidence-supported nutritional interventions for PMS mood symptoms.

Root Causes

Low luteal phase progesterone

This is the single most common hormonal driver of PMS in my experience. Without adequate progesterone in the second half of the cycle, estrogen's effects go unopposed — driving breast tenderness, bloating, mood instability, and sleep disruption. Low progesterone can occur because of anovulation (no ovulation means no corpus luteum means no progesterone), because of a weakly functioning corpus luteum, or because chronic stress is diverting the progesterone precursor pregnenolone toward cortisol production.

Poor estrogen clearance via the gut

Estrogen is processed by the liver and excreted through the bowel — but only if the gut microbiome is healthy and bowel transit is regular. A specific group of gut bacteria (collectively called the estrobolome) produce an enzyme called beta-glucuronidase that can deconjugate estrogen, reactivating it and allowing it to re-enter circulation. When the gut microbiome is disrupted — through antibiotic use, poor diet, or chronic stress — beta-glucuronidase activity increases, estrogen recirculates, and estrogen dominance deepens. Constipation further worsens this: if estrogen doesn't exit through the bowel promptly, it gets reabsorbed.

Blood sugar instability

In the luteal phase, progesterone slightly reduces insulin sensitivity, making blood sugar harder to regulate. This means that the diet and lifestyle habits that might be manageable in the follicular phase can cause significant blood sugar swings in the second half of the cycle. Those swings trigger cortisol and adrenaline release, which worsen mood, anxiety, and cravings in a vicious cycle. Women who notice that their PMS symptoms are significantly worse when they've been eating more sugar or skipping meals are picking up on this mechanism.

Chronic stress and cortisol burden

Cortisol and progesterone share the same biosynthetic precursor — pregnenolone. Under chronic stress conditions, the body's demand for cortisol is given priority, pulling pregnenolone away from progesterone synthesis. This "pregnenolone steal" (a useful conceptual framework, even if the biochemistry is slightly more nuanced) is a significant contributor to low luteal phase progesterone. Beyond this direct effect, elevated cortisol also disrupts sleep, amplifies emotional reactivity, and worsens blood sugar regulation — making every PMS symptom worse.

Magnesium deficiency

Magnesium is one of the most well-researched nutrients in PMS research, with multiple clinical trials showing reductions in mood symptoms, bloating, breast tenderness, and cramping with supplementation. Magnesium is depleted by stress, poor diet, excess sugar, alcohol, and caffeine — a list that describes the modern lifestyle almost perfectly. It's also required for more than 300 enzymatic processes in the body, including progesterone synthesis and the production of GABA. Low magnesium directly reduces GABA tone, worsening anxiety and sleep in the luteal phase.

Liver burden and impaired estrogen metabolism

The liver is responsible for conjugating estrogen into its water-soluble forms for excretion. When the liver is under load — from alcohol, medications, processed foods, or high toxic burden — estrogen metabolism becomes less efficient, and estrogen recirculates rather than being cleared. Supporting liver function through cruciferous vegetables, adequate protein, and minimising alcohol is foundational to estrogen dominance and PMS management.

Where to Start

Nutrition fundamentals

Diet is where the most meaningful short-term changes are possible. The foundational shifts I recommend for PMS are:

• •Significantly reduce sugar and refined carbohydrates — this is the single most impactful dietary change for most women with PMS. Focus especially on the luteal phase, but the whole-cycle foundation matters.
• •Increase dietary fibre — particularly from vegetables, legumes, and whole grains. Fibre binds excess estrogen in the gut and supports its excretion. Aim for 25–35 g per day.
• •Eat cruciferous vegetables daily — broccoli, cauliflower, Brussels sprouts, kale, cabbage, and rocket contain indole-3-carbinol and diindylmethane (DIM), compounds that support healthy estrogen metabolism and promote the production of less potent estrogen metabolites.
• •Prioritise protein at every meal — protein stabilises blood sugar, provides amino acids for neurotransmitter synthesis (including serotonin and dopamine), and supports hormone production. Aim for at least 25–30 g per meal.
• •Reduce or eliminate alcohol — alcohol significantly impairs liver estrogen metabolism and directly worsens PMS symptoms, including mood, sleep, and bloating. Even moderate consumption in the luteal phase can have a meaningful impact.
• •Include anti-inflammatory omega-3 fats — from fatty fish, walnuts, flaxseed, and chia seeds. Omega-3s reduce prostaglandin synthesis, which drives cramping and inflammation in the luteal phase and during menstruation.

Key supplements

Several supplements have strong clinical evidence for PMS specifically:

• •Magnesium glycinate (300–400 mg daily) — the most consistently supported supplement for PMS across the research literature. Reduces bloating, breast tenderness, mood symptoms, and cramping. Take daily, not just premenstrually, for best effect.
• •Vitamin B6 (50–100 mg daily in the luteal phase) — a cofactor for serotonin synthesis and progesterone production. Multiple randomised trials show reductions in PMS mood symptoms. Do not exceed 200 mg daily long-term without practitioner guidance.
• •Vitex agnus-castus / chaste tree berry — the most researched herbal support for PMS, particularly when driven by low luteal phase progesterone. Works by supporting LH secretion and corpus luteum function. Takes 3–6 months of daily use to see the full effect. Not appropriate if you're on hormonal contraception or fertility medications — work with a practitioner.
• •Calcium (1,000 mg daily from food and supplement) — a surprisingly well-supported intervention for PMS. Research from Columbia University found that women with PMS have abnormally low calcium levels and that supplementation significantly reduced both physical and mood symptoms over multiple cycles.
• •DIM (diindylmethane, 100–200 mg daily) — a concentrated form of the active compound from cruciferous vegetables. Supports healthy estrogen metabolism, particularly in women with estrogen dominance driving their PMS.

Stress management as a clinical strategy

I want to be direct about this: stress management for PMS is not about adding a meditation app on top of an overwhelming life. If chronic stress is driving your cortisol burden and depleting your progesterone, the most important intervention is actually reducing the demands that are generating that stress. That might mean setting different boundaries with work, getting more help at home, or having an honest conversation about what's unsustainable in your current situation.

Alongside structural changes, practices that directly lower cortisol output include: daily gentle movement (walking, yoga, swimming — not intense training in the luteal phase), diaphragmatic breathing exercises, prioritising 7–9 hours of sleep, and reducing caffeine. Adaptogenic herbs — ashwagandha, rhodiola, holy basil — can provide meaningful HPA axis support as adjuncts to lifestyle change.

Track your cycle to identify your patterns

One of the most powerful things you can do for PMS is to start tracking your symptoms by cycle phase. Many women discover that their symptoms are more cycle-phase-specific than they realised — that what feels like generalised mood disorder, chronic bloating, or persistent fatigue is actually a luteal phase pattern that resolves reliably once their period arrives. That realisation is both validating and actionable: it tells you exactly where in the cycle to intervene and gives you a measurable way to track improvement over time.

Track mood, energy, appetite, breast tenderness, bloating, sleep, skin, and headaches — and note where in your cycle each entry falls. Within a few months, your pattern will become clear.

Getting the Right Support

Most women see meaningful improvement in PMS symptoms within 2–3 months of consistent nutritional and lifestyle change. Supplements typically require at least 2–3 cycles before their full effect becomes apparent. Vitex, in particular, needs 3–6 months of use — patience matters here.

If your symptoms are severe, if you suspect PMDD, or if self-care measures haven't produced clear improvement after 3–4 months, it's time to work with a hormone-literate practitioner. Useful investigations include mid-luteal progesterone testing (7 days before your next expected period), estradiol, thyroid function, and in some cases, a DUTCH hormone test to assess estrogen metabolism pathways and cortisol patterns.

I've seen women who had been struggling with PMS for years experience a profound transformation once they understood what was driving it and applied the right targeted support. Your luteal phase does not have to be something you survive. It can feel stable, productive, and even enjoyable — and that is what we're working toward.