PMS: What's Really Causing It and How to Fix It

What PMS Actually Is

Premenstrual syndrome is one of the most normalized — and most misunderstood — experiences in women's health. PMS describes a collection of physical and psychological symptoms that appear in the second half of the menstrual cycle, typically in the one to two weeks before menstruation, and resolve within a day or two of bleeding starting. That timing is not random. It is telling you exactly where in your hormonal system something has gone off track.

The symptoms can range from mild to life-disrupting. They include mood changes like irritability, anxiety, and low mood; physical symptoms like breast tenderness, bloating, cramps, and fatigue; and cognitive symptoms like brain fog, difficulty concentrating, and overwhelm. Some women experience a handful of these. Others experience so many that their quality of life is significantly impaired in the two weeks before their period every single month.

The critical thing to understand is this: PMS is not a personality flaw, a sign of emotional weakness, or an inevitable part of being a woman. It is a physiological signal — a message from your body that something in your hormonal environment during the luteal phase needs attention.

The Luteal Phase and What Goes Wrong

After ovulation, your cycle enters what is called the luteal phase — the second half of your cycle, spanning roughly days 15 through 28 in a typical 28-day cycle. During this time, the follicle that released the egg transforms into the corpus luteum, a temporary endocrine gland that produces progesterone. Estrogen also remains present, though it dips slightly after ovulation before rising again mid-luteal.

In a healthy cycle, these two hormones exist in balance. Progesterone is calming, anti-inflammatory, and acts on the GABA receptors in the brain — the same receptors targeted by anti-anxiety medications. Estrogen at the right levels supports mood, energy, and libido. When the balance shifts — specifically when progesterone is insufficient relative to estrogen — the result is the cluster of symptoms we call PMS.

The medical term for this imbalance is estrogen dominance, which does not necessarily mean estrogen is high in absolute terms. It means progesterone is relatively low, leaving estrogen's effects unopposed. This is an important distinction, because many women with PMS have estrogen levels that look "normal" on a lab report but experience significant symptoms because their progesterone is inadequate to counterbalance it.

Low Progesterone and PMS

Progesterone is produced primarily by the corpus luteum after ovulation. That means you need to actually ovulate to make meaningful amounts of progesterone. Many women cycle without ovulating — a phenomenon called anovulation — and yet they still bleed. These cycles look normal from the outside but lack the progesterone that a healthy luteal phase requires.

Even when ovulation occurs, progesterone can still fall short. Factors that suppress progesterone production include:

• Chronic stress, which diverts the progesterone precursor pregnenolone toward cortisol production (known as the progesterone steal)
• Under-eating or low body fat, which signals to the body that it is not a safe time to sustain a pregnancy
• Thyroid dysfunction, particularly hypothyroidism, which impairs ovulation quality and luteal function
• Elevated prolactin levels, which can suppress the LH surge needed to trigger ovulation
• Nutrient deficiencies, particularly in vitamin B6, zinc, and magnesium — all of which are required for progesterone synthesis and metabolism

When progesterone is low, the brain's GABA system is deprived of its primary support during the luteal phase. This is a direct neurochemical pathway to the irritability, anxiety, and emotional volatility that characterize PMS for so many women.

Blood Sugar Instability

One of the most underappreciated drivers of PMS is blood sugar dysregulation. In the luteal phase, insulin sensitivity naturally decreases — meaning your cells become slightly more resistant to insulin's signal to absorb glucose. This is a normal physiological shift. But when it occurs on top of an already unstable blood sugar pattern, the result is exaggerated PMS symptoms.

Blood sugar swings trigger cortisol release. Cortisol in the luteal phase competes with progesterone and further suppresses it. This creates a feedback loop: unstable blood sugar leads to cortisol spikes, cortisol steals progesterone, low progesterone worsens mood and cravings, cravings lead to carbohydrate-heavy eating, and the cycle continues.

This is also why so many women experience intense sugar and carbohydrate cravings in the week before their period. The body is attempting to quickly correct dropping blood sugar, but the foods chosen — refined carbohydrates, chocolate, processed snacks — cause a rapid spike followed by an equally rapid crash, making symptoms worse.

Prioritizing protein and fat at each meal, eating regularly (every 3 to 4 hours during the luteal phase), and reducing refined sugar and alcohol in the two weeks before your period can produce noticeable improvements in PMS symptoms within one to two cycles.

Gut Health and Estrogen Metabolism

Your gut plays a more significant role in PMS than most people realize. A specific collection of gut bacteria called the estrobolome is responsible for metabolizing estrogens that have been processed by the liver and are awaiting excretion. When this microbial community is out of balance — a state called dysbiosis — it can reactivate estrogens in the colon, allowing them to be reabsorbed into circulation rather than eliminated.

This recirculation of estrogen contributes directly to estrogen dominance and, by extension, to worsening PMS. Signs that gut-driven estrogen excess may be a factor for you include bloating and digestive changes that worsen premenstrually, a history of antibiotic use, constipation (which slows estrogen excretion), and symptoms that do not improve with other interventions.

Supporting the estrobolome involves increasing dietary fiber — particularly from cruciferous vegetables like broccoli, cauliflower, and Brussels sprouts, which contain compounds that directly support estrogen detoxification — as well as reducing inflammatory foods, managing intestinal permeability, and in some cases working with a practitioner on targeted probiotic therapy.

What Actually Works for PMS

Effective PMS management is not about suppressing your cycle with hormonal contraception and calling it fixed. It is about identifying and addressing the underlying imbalances driving your symptoms. The approaches with the strongest evidence include:

• Magnesium glycinate or bisglycinate (300–400 mg daily) — reduces muscle tension, headaches, mood symptoms, and fluid retention associated with PMS
• Vitamin B6 (50–100 mg daily) — supports progesterone production and dopamine synthesis, with multiple randomized controlled trials showing significant PMS symptom reduction
• Vitex agnus-castus (chasteberry) — shown in clinical trials to reduce PMS symptoms by modulating dopamine and prolactin, supporting the LH surge and improving luteal phase progesterone levels
• Blood sugar stabilization through consistent protein intake, reducing refined carbohydrates, and eating regularly throughout the day
• Stress reduction — not as a platitude, but as a genuine clinical necessity. Even one daily stress-reduction practice (breathwork, yoga, walking, meditation) measurably reduces cortisol and its downstream impact on progesterone
• Addressing constipation and supporting daily bowel movements to enhance estrogen clearance
• Testing — specifically a DUTCH hormone test or a day-21 serum progesterone level — to confirm whether low progesterone is actually the driver and to rule out other factors

PMS is common. It is not, however, normal in the sense of being inevitable or untreatable. Most women who commit to addressing their luteal phase hormonal environment see meaningful improvement within two to three cycles. Your cycle can tell you a great deal about your health — PMS is one of the clearest signals it sends, and it is one worth listening to.

This article is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider for diagnosis and treatment of any health condition.