Tranexamic acid: uses, side effects and cautions

Tranexamic acid belongs to the group of medicines that control bleeding. The NHS describes it as helping your blood to clot, which is why it appears in very different settings: a gynaecology clinic, an ear, nose and throat department, a dentist and a haematology ward.

The NHS lists nosebleeds, heavy periods, tooth extraction and hereditary angioedema, which is swelling under the skin. It is also used to prevent bleeding before surgery in people who have a bleeding disorder. Brand names given by the NHS are Cyklokapron and Evana Heavy Period Relief.

It comes as tablets, as a mouthwash and as an injection. The injection form is normally given in hospital rather than at home.

Your body already has a natural clotting process. Tranexamic acid supports it by stopping fibrin, the mesh that holds a clot together, from breaking down too soon. The practical result is that a clot lasts long enough for the bleeding to settle.

The NHS says it can take up to 24 hours for the medicine to work fully, so it is not an instant fix for a heavy flow that has already started. Because it only acts while it is in the body, it is used in short bursts for episodes of bleeding rather than as a standing hormone-style treatment.

The NHS says most adults and children of all ages can take tranexamic acid when a doctor prescribes it. Adults aged 18 and over can also obtain a pharmacy-sold version for heavy periods.

Tell the prescriber or pharmacist first if any of the following apply, because they affect whether it is suitable or how it is used:

• You have had an allergic reaction to tranexamic acid or any other medicine.

• You have had a deep vein thrombosis or a pulmonary embolism, which are clots in a leg vein or the lungs.

• You have a rare condition called coagulopathy, in which many small clots form and are followed by abnormal bleeding.

• You have epilepsy.

• You have kidney problems, which can mean a lower dose.

• You are pregnant or trying to become pregnant.

• Your periods are irregular, since a doctor needs to look for the cause before treating the bleeding.

For adults the NHS gives the usual tablet dose as 2 or 3 tablets of 500mg, taken three times a day, with 2 tablets three times a day being the most common pattern. Doses for children are set by the doctor according to weight and age, and your dose may change if bleeding is not controlled or if your kidneys work less well. Always follow the label from your prescriber or pharmacist.

Swallow tablets whole with water, with or without food, and spread the doses evenly through the day. The usual length of treatment is short: about 4 days for heavy periods or 7 days for other bleeding. For hereditary angioedema it is taken when needed, for example around dental treatment.

If you miss a dose, take it when you remember unless the next one is nearly due, in which case skip it. Never take two doses together. Someone who takes one extra dose is unlikely to come to harm, but may have nausea, diarrhoea or dizziness.

The NHS says most people have no side effects with the tablets or mouthwash and lists no common side effects. Serious problems are rare, affecting fewer than 1 in 1,000 people, but the ones that matter involve clots and allergy.

• Call NHS 111 for eyesight problems, or for a leg or arm that is painful, swollen, red and warm to touch, which can be a sign of a clot.

• Call 999 or go to A&E for chest pain with shortness of breath and coughing, or coughing up blood, which can be a clot in the lungs.

• Call 999 for signs of a serious allergic reaction, such as swelling of the lips, mouth, throat or tongue, difficulty breathing, confusion, fainting, or a swollen, blistered or peeling rash.

Tranexamic acid is not often recommended in pregnancy but can be used when needed, and only on a doctor's prescription. It may be used after birth for heavy bleeding or clotting disorders. The NHS says it is safe to use while breastfeeding if your baby is healthy, because only small amounts reach the milk; watch for feeding difficulties, unusual restlessness or stomach upset in the baby. It does not reduce fertility in men or women on the evidence the NHS cites.

The one named interaction is the combined contraceptive pill, where taking both could add a very small increase in clot risk. Tranexamic acid does not stop any type of contraception from working, but anyone on the combined pill should raise it with their doctor. The NHS also says there is not enough information to call herbal remedies and supplements safe alongside it.

You can drink alcohol while taking tranexamic acid, and the NHS says it will not affect your ability to drive or ride a bike. Eating and drinking can continue as normal.

People with regular nosebleeds or heavy periods can use it over many months or years, but each use is normally a short run of days during the bleeding episode. The NHS notes that evidence is still preliminary and does not recommend it for skin discolouration.

The NHS names etamsylate and desmopressin as other medicines used for bleeding, which work in different ways from tranexamic acid. Which option fits depends on why you are bleeding, so the cause matters more than the drug name. Background on the causes is in our guides to heavy periods and nosebleeds.

In the UK tranexamic acid is a prescription medicine, with a pharmacy-sold tablet for heavy periods limited to adults aged 18 and over. If you think you have had a side effect, you can report it through the Yellow Card scheme run by the MHRA.