Pharmacology · Antifibrinolytic haemostatics

Tranexamic acid !

A lysine analogue that blocks clot breakdown. WHO recommends it for postpartum haemorrhage; it is also used in trauma, surgery and heavy periods.

Updated 2026-11-01

Class: Antifibrinolytic haemostatics
Target: Lysine-binding sites (kringle domains) of plasminogen
ATC code: B02AA02
WHO Model List of Essential Medicines

Also called: TXA

Lysine-binding sites (kringle domains) of plasminogenTranexamic acid

The figure shows tranexamic acid (trans-4-aminomethylcyclohexane-1-carboxylic acid) bound in the lysine-binding pocket of kringle 1 of human plasminogen.

Target in 3D: Lysine-binding sites (kringle domains) of plasminogen. PDB structure 1CEB (RCSB PDB, public domain). View the structure at RCSB PDB

Mechanism of action

Tranexamic acid is a synthetic lysine analogue. It occupies the lysine-binding sites on plasminogen and plasmin, so they can no longer attach to fibrin. Fibrinolysis slows down and the clots that form at a bleeding site last longer. It does not activate coagulation.

Plasminogen binds fibrin through its lysine-binding sites
The drug, a lysine analogue, occupies those sites
Plasminogen and plasmin cannot attach to fibrin
The clot is protected from early breakdown

Pharmacokinetics

Absorption: Given intravenously or by mouth
Distribution: Crosses the placenta; cord blood levels are similar to the mother's
Elimination: Kidneys, almost entirely unchanged; lower doses are used in renal impairment
Half-life: About 2 hours (terminal phase)

Indications

Treatment of postpartum haemorrhage, together with standard obstetric care (WHO recommendation) Postpartum haemorrhage →
Major trauma with bleeding, during resuscitation Major trauma (polytrauma): ATLS primary survey →
Heavy menstrual bleeding (tablets) Abnormal uterine bleeding →
Haemophilia, to reduce bleeding around tooth extraction Haemophilia A and B →
Reducing blood loss in surgery such as hip or knee replacement or cardiac surgery

Adverse effects

Common

Nausea, vomiting, diarrhoea
Dizziness
Visual disturbances

Contraindications

Neuraxial (intrathecal or epidural) injection
Subarachnoid haemorrhage
Active intravascular clotting
Hypersensitivity to tranexamic acid

Key interactions

Hormonal contraceptives: Together they raise the risk of thrombosis
Factor IX complex and anti-inhibitor coagulant concentrates: Pro-thrombotic products; the combination increases thrombosis risk

What is monitored

Bleeding and haemoglobin
Kidney function
Signs of thrombosis (leg swelling, chest pain, neurological deficit)
Vision; it is stopped if visual symptoms appear

Administration and safety

The injection is for intravenous use only; fatal reactions have followed accidental intrathecal injection
Label syringes with the drug and route; keep it apart from local anaesthetics and other solutions used at the same time
Given slowly intravenously; rapid injection can cause hypotension

Nursing care

In postpartum haemorrhage, give it alongside uterotonics and the other steps of the protocol and record the time
Check the route before every injection, especially in obstetric and spinal anaesthesia settings
Watch for seizures, visual changes and signs of thrombosis
Check kidney function before repeated doses

Pregnancy and breastfeeding

It crosses the placenta; it is used in pregnancy and childbirth when the benefit justifies it, and WHO recommends it for postpartum haemorrhage.

Test yourself

Think of the answer, then tap the question to see it.

How does tranexamic acid reduce bleeding?

It blocks the lysine-binding sites of plasminogen, so plasmin cannot break down fibrin.

Which obstetric emergency has a WHO recommendation for it?

Postpartum haemorrhage.

Which route error is dangerous?

Neuraxial (intrathecal or epidural) injection: seizures, arrhythmias and death.

Why is the dose lowered in kidney failure?

It is excreted almost entirely unchanged in urine.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: DailyMed - TRANEXAMIC ACID injection, solution (DailyMed (U.S. National Library of Medicine), 2026); WHO recommendation on tranexamic acid for the treatment of postpartum haemorrhage (World Health Organization, 2017); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 36 (McGraw Hill, 2023); Tranexamic Acid: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2017).

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Representative model, for educational purposes only.