Antifibrinolytic (Gynaecological Use) Pregnancy: Avoid — insufficient data for HMB indication; IV tranexamic acid is used in obstetric haemorrhage (different risk-benefit context)

Tranexamic Acid (Heavy Menstrual Bleeding)

Brand names: Cyklokapron, Urimex

Adult dose

Dose: 1 g three times daily for up to 4 days during menstruation

Route: Oral

Frequency: Three times daily (during heavy days only)

Max: 4 g/day; maximum 4 days per cycle

First-line pharmacological treatment for idiopathic HMB in women who do not require contraception; start at onset of heavy flow; does not affect cycle length or regularity

Paediatric dose

Dose: Not established for menstrual use N/A/kg

Route: N/A

Frequency: N/A

Max: N/A

Adolescent HMB: specialist use only

Dose adjustments

Renal

Reduce dose in renal impairment — risk of accumulation; CrCl 20-50: 15 mg/kg twice daily; CrCl <20: 15 mg/kg once daily

Hepatic

No dose adjustment required

Paediatric weight-based calculator

Patient weight (kg)

Adolescent HMB: specialist use only

Clinical pearls

NICE NG88 (Heavy Menstrual Bleeding 2018): tranexamic acid is first-line pharmacological treatment for HMB with no identified pathology, when the woman does not require contraception — reduces blood loss by ~50% vs placebo in trials; levonorgestrel IUS (Mirena) preferred for women also requiring contraception
Mechanism of action: competitively inhibits plasminogen activation by binding lysine-binding sites — prevents fibrinolysis and stabilises clots; does not affect normal coagulation or cause thrombosis at HMB oral doses
Unlike NSAIDs (mefenamic acid): tranexamic acid does not reduce dysmenorrhoea — both can be combined for women with HMB AND dysmenorrhoea; NSAIDs address pain, tranexamic acid addresses blood loss
WOMAN trial (NEJM 2017): IV tranexamic acid within 3 hours of postpartum haemorrhage significantly reduced maternal mortality — this obstetric context (tranexamic_obstetric) is distinct from the HMB oral use here
Endometrial assessment: tranexamic acid for HMB should not be started without excluding endometrial pathology in women ≥45 or with irregular bleeding — consider pipelle biopsy or hysteroscopy before long-term treatment

Contraindications

Active thromboembolic disease
History of convulsions (high doses)
Subarachnoid haemorrhage (in other contexts)
Ureteric obstruction (in haematuria context — note: this is GI/haem context, not menstrual use)

Side effects

Nausea
Vomiting
Diarrhoea
Abdominal pain
Headache
Thromboembolic events (theoretical, rarely reported at oral doses for HMB)
Colour vision disturbance (prolonged/high-dose IV use)

Interactions

Combined oral contraceptives — theoretical additive thrombotic risk; not contraindicated but monitor
Factor IX concentrate — avoid combination (thrombosis risk)
MHRA 2010: no convincing evidence that therapeutic oral doses for HMB increase VTE risk

Monitoring

Menstrual blood loss assessment (PBAC or patient-reported improvement)
VTE symptoms (counsel)
Response at 3 cycles — review

Reference: BNFc; BNF 90; NICE NG88 (Heavy Menstrual Bleeding 2018); WOMAN trial (Shakur et al. Lancet 2017 — PPH context); MHRA guidance on VTE and tranexamic acid; SPC Cyklokapron. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators