Heavy Menstrual Bleeding and Period Pain: A Stepwise Toolkit

First, exclude a cause you can't drug away

Before any prescription, the question is whether the bleeding is a symptom of something structural or systemic. Heavy menstrual bleeding (menorrhagia) is defined by its impact on the woman — blood loss that interferes with physical, social or emotional quality of life — not by a number in a bucket. The first job is to sort the many women with no demonstrable pathology from the few with a cause that drugs won't fix. Structural culprits include fibroids and polyps; systemic ones include a bleeding disorder such as von Willebrand disease, or a clotting problem, and thyroid dysfunction. A history of easy bruising or bleeding since menarche should prompt a clotting screen — this connects directly to the Haematology section, where inherited bleeding disorders are worked up. Where a fibroid or endometriosis is driving the bleeding, management shifts toward the Endometriosis and fibroids chapter. Only once structural and systemic causes are addressed does the pharmacological ladder for idiopathic heavy bleeding come into play.

First-line: the levonorgestrel intrauterine system

When no structural cause needs surgery and the woman is happy with a hormonal, contraceptive option, NICE names the levonorgestrel-releasing intrauterine system (the IUS) as first-line. It is a small device that releases a steady, tiny dose of levonorgestrel — a progestogen — directly onto the endometrium. The local hormone makes the endometrium thin and atrophic, so month after month there is far less lining to shed. Blood loss typically falls by 70–95%, and many women become amenorrhoeic altogether. Because the progestogen acts locally, systemic levels stay low, and as a bonus the device is one of the most effective contraceptives available. The catch worth warning about is irregular spotting for the first three to six months while the endometrium settles — counsel for it, or women abandon the device before it has done its job. The IUS itself is covered in depth in the Contraception chapter; here it simply happens to be the best treatment for bleeding too.

Non-hormonal options: tranexamic acid and NSAIDs

Some women want to conceive, or want no hormones at all — and here the pharmacology gets elegant. The first non-hormonal drug is tranexamic acid, an antifibrinolytic. Normally, plasminogen is converted to plasmin, the enzyme that dissolves clots; the endometrium of women with heavy bleeding is unusually rich in this fibrinolytic activity, so clots that should stem the flow are broken down too fast. Tranexamic acid blocks the activation of plasminogen, stabilising the clot in the uterine bed and cutting blood loss by roughly a third to a half. It is taken only during the days of heavy bleeding — not all month — which makes it convenient and non-contraceptive. This is the very same drug, working by the very same mechanism, that saves lives in trauma and in postpartum haemorrhage (the WOMAN trial), and which you will meet again in the Haematology section; the natural caution is a history of venous thromboembolism. The second option is an NSAID such as mefenamic acid. Prostaglandins are over-produced in the endometrium of women with heavy, painful periods; NSAIDs inhibit cyclo-oxygenase and cut prostaglandin synthesis, reducing blood loss by about a quarter to a third — and, crucially, easing the pain at the same time. That dual action, dissected in the Inflammation and joints section, is why an NSAID is often the single most useful tablet for a woman whose periods are both heavy and painful.

Hormonal options and the refractory case

If the IUS is declined and non-hormonal tablets are not enough, the combined oral contraceptive pill lightens bleeding by suppressing ovulation and thinning the endometrium, while also delivering contraception and cycle predictability — remembering its own contraindications (migraine with aura, high VTE risk), which are laid out fully in the Contraception chapter. Cyclical oral progestogens, such as norethisterone given for the second half of the cycle (or in higher doses to arrest an acute bleed), are another lever. For the genuinely refractory case heading toward theatre, GnRH analogues can be used short-term: by continuously stimulating — and thereby down-regulating — the pituitary GnRH receptor, they shut down FSH and LH, induce a temporary menopausal state, and shrink the endometrium (and any fibroids) before surgery. Because that hypo-oestrogenic state causes bone loss and menopausal symptoms, use is limited to a few months, often with add-back hormone therapy; the mechanism and its figure live in the Endometriosis and fibroids chapter.

Dysmenorrhoea: pain that is prostaglandin, made visible

Period pain is not simply "cramps" — it is a prostaglandin storm you can target directly. In primary dysmenorrhoea — painful periods with no underlying pelvic disease, typically starting within a year or two of menarche — the mechanism is beautifully specific. As the corpus luteum regresses and progesterone falls, the endometrium releases a surge of prostaglandins. These make the myometrium contract intensely and constrict its vessels, so the uterine muscle becomes transiently ischaemic — cramping, colicky pain, sometimes with the nausea and diarrhoea of prostaglandin spillover. Because the whole cascade is prostaglandin-driven, NSAIDs are first-line: mefenamic acid, ibuprofen or naproxen block cyclo-oxygenase and stop the prostaglandins at their source. The clinical trick is timing — start the NSAID at the very onset of pain or bleeding (or just before, if periods are predictable) rather than waiting for pain to peak, because it is far easier to prevent the prostaglandin surge than to chase it. Where an NSAID alone is insufficient or contraception is also wanted, hormonal methods work upstream: the combined pill suppresses ovulation and thins the endometrium, and the levonorgestrel IUS thins it locally — both leaving less prostaglandin-producing tissue behind.

The essential fork is between primary and secondary dysmenorrhoea. Pain that begins years after menarche, that worsens over time, that strikes deep during intercourse, or that no longer responds to NSAIDs and hormones, points away from simple prostaglandins and toward secondary dysmenorrhoea — a structural cause such as endometriosis, adenomyosis, fibroids, or pelvic inflammatory disease. That patient needs investigation, not just a stronger analgesic, and her management belongs to the Endometriosis and fibroids chapter. Missing this switch — treating cyclical progressive pelvic pain as ordinary period cramps for years — is one of the classic delays in gynaecology.