The Hormone Harmony Guide

1. Understanding the menstrual cycle

The menstrual cycle is a monthly-ish conversation between the brain and the ovaries. It runs from the first day of one period to the day before the next, and its job is to mature and release an egg while preparing the uterine lining for a possible pregnancy. Cycle length varies, and that variation is often normal. Read the illustrated breakdown on our cycle health page.

2. The role of estrogen and progesterone

Estrogen (mainly estradiol during the reproductive years) builds the uterine lining and also influences bone density, skin, the vaginal and urinary tissues, cholesterol metabolism and the brain. Progesterone, produced mainly after ovulation, stabilises the lining. When both fall at the end of the cycle, a period follows.

You'll often see “hormone imbalance” online used as a catch-all explanation. In medicine, hormone problems are specific — for example, low thyroid hormone or high androgens — and are identified through clinical assessment and, where appropriate, tests interpreted in context. Hormone levels naturally change across the cycle, so a single result can be misleading without clinical context.

3. Common menstrual symptoms and cycle variability

Cramps, bloating, breast tenderness, headaches and mood shifts are commonly reported. Many people manage mild symptoms with heat, rest and over-the-counter pain relief as directed on the label. Symptoms are worth discussing when they are severe, worsening, or affecting school, work or relationships. PMDD — a severe, cyclical mood condition — is recognised and treatable.

4. Understanding perimenopause and menopause

Perimenopause is the transition, menopause is the milestone (12 months without a period), and postmenopause is everything after. During perimenopause, hormone levels can swing rather than steadily decline, which helps explain why symptoms can come and go. Explore the stages on our menopause page.

5. Common menopause symptoms and management options

Hot flushes, night sweats, sleep disruption, mood changes, brain fog, vaginal dryness and joint aches are frequently reported. Options include hormone therapy, local vaginal estrogen, non-hormonal prescription medicines and CBT. The right choice depends on individual history — which is why guidelines emphasise shared decision-making with a clinician.

6. PCOS education and common misconceptions

Polycystic ovary syndrome is a common hormonal condition. The 2023 international guideline uses criteria based on irregular or absent ovulation, clinical or biochemical signs of higher androgens, and polycystic ovarian morphology on ultrasound (or raised AMH in adults) — after other causes are excluded.

• Myth: you must have ovarian cysts. Fact: the “cysts” are immature follicles and are not required for diagnosis.
• Myth: PCOS only affects fertility. Fact: it is also linked to insulin resistance, type 2 diabetes risk and mental health.
• Myth: one diet cures PCOS. Fact: healthy lifestyle helps, but there is no single proven “PCOS diet”.

See our PCOS resource guide.

7. Endometriosis awareness and clinical evaluation

Endometriosis occurs when tissue similar to the uterine lining grows outside the uterus. The WHO estimates it affects roughly 10% of reproductive-age women and girls worldwide. Painful periods, pain with sex, bowel or bladder pain and fertility difficulties are common symptoms, and diagnosis is often delayed. Evaluation may include history, examination, imaging and sometimes laparoscopy. Read our endometriosis guide.

8. Thyroid health and menstrual changes

Thyroid disorders are more common in women. An underactive thyroid may be associated with heavier or irregular periods; an overactive thyroid with lighter or less frequent periods. Because tiredness, mood changes and cycle changes overlap with perimenopause, clinicians may check thyroid function with a blood test. See the thyroid guide.

9. Sleep, nutrition and physical activity

Regular activity (including muscle strengthening), a varied diet, good sleep habits, not smoking and moderating alcohol support bone, heart and mental health throughout life. These habits support well-being but should not be presented as cures for hormonal conditions. See our physical activity guide.

10. Questions to ask a healthcare professional

Use our appointment question list. Clear notes about timing, severity and impact help clinicians understand what you're experiencing.

11. Recognising symptoms that may warrant medical assessment

12. How to evaluate health claims and find reliable sources

• Who is behind it? Prefer public-health bodies, national health services, hospitals and professional associations.
• Is it dated and sourced? Trustworthy pages show review dates and cite evidence.
• Is someone selling something? Be cautious of “hormone balancing” supplements, detoxes and tests sold alongside the advice.
• Does it promise a cure? Claims that one product fixes complex conditions are a red flag.
• Is a personal story presented as proof? Experiences are valid but are not evidence of effectiveness for everyone.