Tranexamic Acid
Is It Right for You?
A complete guide to Tranexamic Acid — what it treats, how it works, dosages, side effects, and when a clinician may prescribe it following an online consultation.
What Is Tranexamic Acid?
Tranexamic acid is a synthetic antifibrinolytic agent that reduces bleeding by inhibiting the breakdown of blood clots. It is available in tablets (500 mg) and as an intravenous injection (100 mg/mL). Oral tranexamic acid tablets are widely used in primary care and gynaecology for the management of heavy menstrual bleeding (HMB), while intravenous tranexamic acid is a cornerstone of surgical, trauma, and obstetric haemorrhage management in secondary care.
Tranexamic acid is not a haemostatic agent in the traditional sense — it does not promote clot formation directly. Rather, it stabilises clots that have already formed by preventing their premature dissolution, allowing the body's normal haemostatic mechanisms to work effectively.
Oral tranexamic acid is a prescription-only medication in the UK for the management of heavy menstrual bleeding, though it is licensed and available over the counter in some other countries. A clinician must assess the cause of bleeding before prescribing.
What Conditions Is Tranexamic Acid Used For?
Tranexamic acid is indicated for:
the principal indication for oral tranexamic acid in primary care; reduces menstrual blood loss by 40–60% on average; used only during menstruation
IV tranexamic acid is used perioperatively to reduce blood loss in elective and emergency surgery (orthopaedic, cardiac, and major general surgery)
IV tranexamic acid is a standard of care in major trauma management (evidenced by the CRASH-2 trial); most effective when given within 3 hours of injury
WHO-recommended IV tranexamic acid for PPH management alongside uterotonic agents
tranexamic acid mouthwash is used to control dental extraction bleeding in patients on warfarin or direct oral anticoagulants (DOACs)
used for short-term prophylaxis around procedures
In heavy menstrual bleeding, tranexamic acid controls blood loss during menstruation but does not address the underlying gynaecological cause (such as fibroids, endometrial polyps, adenomyosis, or endometrial pathology). Appropriate investigation of HMB is essential before and alongside treatment, particularly to exclude uterine malignancy.
How Does Tranexamic Acid Work?
Tranexamic acid is a synthetic derivative of the amino acid lysine. Its antifibrinolytic mechanism is well-characterised:
Plasminogen and plasmin inhibition: The fibrinolytic system is responsible for dissolving blood clots. Plasminogen is converted to plasmin — the principal clot-dissolving enzyme — by tissue plasminogen activator (tPA) and other activators. Plasmin then degrades fibrin (the structural protein of blood clots) into fibrin degradation products, breaking down the clot.
Tranexamic acid reversibly binds to the lysine-binding sites on plasminogen and plasmin, the sites through which these molecules attach to fibrin within a clot. By occupying these binding sites, tranexamic acid prevents plasminogen from binding to fibrin and blocks the action of already-formed plasmin on fibrin. The clot is therefore protected from premature fibrinolytic breakdown.
In heavy menstrual bleeding specifically, the endometrium releases high levels of tPA and has an upregulated fibrinolytic system relative to the coagulation system — resulting in excessive clot dissolution and heavy bleeding. Tranexamic acid corrects this imbalance by reducing fibrinolysis in the endometrium, allowing effective clot formation and haemostasis.
Dosages & Administration
The correct dose depends on the type and severity of infection, age, weight, and kidney function. Always follow your clinician's instructions. The table below is for general reference only.
Administration Tips
Always follow your clinician's instructions. For oral use in HMB, tranexamic acid is taken only during the days of heavy bleeding. It should not be taken throughout the entire menstrual cycle — it is a short-course intervention taken only during the heaviest bleeding days (typically up to 4 days maximum per cycle). Can be taken with or without food. Gastrointestinal side effects may be reduced by taking tablets with food.
Side Effects of Tranexamic Acid
Most side effects are mild and resolve on their own. Serious side effects are rare but require immediate medical attention.
- Nausea and vomiting
- Diarrhoea
- Abdominal discomfort
- Headache
- Dizziness (particularly with IV administration)
- Thromboembolic events --- deep vein thrombosis (DVT) and pulmonary embolism (PE) are theoretically possible; clinical risk at oral doses used for HMB is low in otherwise healthy women.
- Retinal venous and arterial occlusion --- rare but reported; sudden changes in vision during treatment require urgent ophthalmological assessment.
- Seizures --- reported particularly with high-dose IV administration; rare at oral doses.
- Severe hypersensitivity reactions --- anaphylaxis; rare.
Tranexamic acid inhibits fibrinolysis and could theoretically promote thrombosis by stabilising clots that would otherwise be dissolved. It should be used with caution in patients with a personal or family history of DVT, PE, stroke, or other thromboembolic events.
Drug Interactions
Tranexamic acid may interact with other medications, including combined oral contraceptives and procoagulant agents. Always inform your clinician about all medications you are taking.
both COCPs and tranexamic acid carry an inherent thromboembolic risk; concurrent use for management of HMB increases combined thrombotic exposure; clinical benefit-risk assessment is required before co-prescribing.
combination with antifibrinolytic agents increases the risk of thrombosis; avoid unless under haematologist supervision.
tranexamic acid may partially counteract the effect of anticoagulation; however, it is used clinically post-dental extraction in anticoagulated patients as a local mouthwash (not systemic) to control bleeding without fully reversing anticoagulation; systemic concurrent use requires specialist assessment.
no significant additional thromboembolic risk identified; progestogen-only contraceptives are generally preferred over COCPs in women requiring concurrent antifibrinolytic therapy.
Important Warnings
Tranexamic acid is contraindicated in patients with a history of thromboembolic disease (DVT, PE, stroke, or arterial thrombosis) and in those with known thrombophilia (e.g., Factor V Leiden, antiphospholipid syndrome, protein C or S deficiency). The antifibrinolytic action of tranexamic acid may increase thrombotic risk in these patients.
Tranexamic acid is renally excreted. Dose reduction is required in patients with renal impairment to prevent drug accumulation and seizure risk. Clinician review is essential in patients with reduced eGFR.
Tranexamic acid manages the symptom of heavy bleeding; it does not treat the cause. Heavy menstrual bleeding can be caused by fibroids, polyps, adenomyosis, endometrial hyperplasia, or malignancy. Appropriate gynaecological assessment — including pelvic examination, ultrasound, and endometrial sampling where indicated — is essential before attributing HMB to dysfunctional uterine bleeding and initiating symptomatic treatment.
Tranexamic acid is generally contraindicated in upper urinary tract bleeding (from the kidney or ureter) as the antifibrinolytic action can cause clot formation and obstruction within the urinary collecting system (clot colic or ureteric obstruction).
Speak to a Clinician About Treatment
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The treatment you need, when you need it.
Tranexamic Acid FAQs
Clinical trials consistently demonstrate that oral tranexamic acid reduces menstrual blood loss by approximately 40–60% compared to no treatment. Most women notice a meaningful reduction in the heaviness of flow, the number of days with heavy bleeding, and the number of pads or tampons required.
No. For heavy menstrual bleeding, tranexamic acid is taken only on the days of heavy flow — typically the first 3–4 days of the period. It is not taken throughout the entire cycle or on non-bleeding days.
if you are taking a combined oral contraceptive pill (COCP), your clinician will carefully review whether adding tranexamic acid is appropriate, as both carry a small thromboembolic risk. Progestogen-only pills and hormonal IUDs (such as the Mirena coil) are alternatives that both provide contraception and substantially reduce heavy menstrual bleeding without additive thrombotic risk.
At standard oral doses used for heavy menstrual bleeding, the absolute thromboembolic risk in otherwise healthy women without pre-existing risk factors is low based on available clinical evidence. However, it is contraindicated in patients with a history of DVT, PE, or stroke, and in those with known clotting disorders. Inform your clinician of any personal or family history of blood clots before taking tranexamic acid.
If tranexamic acid does not provide sufficient symptom control, alternative or additional treatments include hormonal therapies (levonorgestrel-releasing IUS, the Mirena coil, combined oral contraceptive pill, progestogens), non-hormonal options (NSAIDs such as mefenamic acid), and — following gynaecological assessment — procedural or surgical options such as endometrial ablation. Your clinician will guide you through these options based on your individual circumstances.