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Bosentan tablets


The usual dose is one tablet twice daily, morning and evening. You can take bosentan either with or without food.

The most common side-effects are headache, and swollen feet and ankles.

You must avoid getting pregnant while you are taking bosentan because it could cause harm to an unborn baby. If you are a woman who could get pregnant, you must use suitable contraception. Please discuss this with your doctor before you take bosentan.

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About bosentan

Type of medicine

A vasodilator antihypertensive medicine, called an endothelin receptor antagonist

Used for

Pulmonary arterial hypertension; to prevent skin ulcers in people with systemic sclerosis

Also called


Available as


You will have been prescribed bosentan for one of two different conditions: pulmonary arterial hypertension, or systemic sclerosis. It will be prescribed for you by a doctor who is a specialist.

Pulmonary arterial hypertension (PAH) is a condition where there is too high a blood pressure in the blood vessels that supply your lungs from your heart. Bosentan relaxes the muscle cells in the walls of the blood vessels to your lungs, allowing them to become wider (dilated). This reduces the pressure in these blood vessels and allows blood to flow more easily through them. In turn, this increases the supply of blood to your lungs and improves your ability to do physical activities.

Systemic sclerosis is an autoimmune connective system disorder. This is a disorder where your immune system (which normally protects your body) causes damage to your connective system. Some people with systemic sclerosis develop ulcers on their fingertips or toes as a symptom of the condition. These ulcers can be painful and difficult to heal. Bosentan can help prevent new ulcers from occurring.

Before taking bosentan

Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking bosentan tablets it is important that your doctor knows:

  • If you are or could become pregnant, or if you are breastfeeding.

  • If you have problems with the way your liver works.

  • If you have a low blood pressure.

  • If you have a rare inherited blood disorder called porphyria.

  • If you have ever had an allergic reaction to a medicine.

  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.

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How to take bosentan tablets

  • Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about bosentan, and it will also provide you with a full list of the side-effects which you could experience from taking it.

  • Take bosentan tablets exactly as your doctor tells you to. They are usually taken twice daily, morning and evening. There are two different strengths of tablet - 62.5 mg and 125 mg. It is likely you will be started on the lower strength and then changed to the higher strength after about four weeks. If bosentan has been prescribed for a child, the dose will be calculated from your child's weight and so will be different to the doses given here.

  • Swallow the tablet whole, preferably with a drink of water. You can take bosentan tablets either with or without food.

  • If you forget to take a dose, take it as soon as you remember (unless it is nearly time for your next dose, in which case take the next dose when it is due and leave out the forgotten dose). Do not take two doses together to make up for a missed dose.

Getting the most from your treatment

  • Try to keep all your regular appointments with your doctor. This is so your doctor can check on your progress. You will need to have regular blood tests while on bosentan to check that you do not develop anaemia. Your doctor will also want to check that your liver stays healthy. Signs that your liver may not be working properly are feeling sick, a high temperature, dark urine, yellowing of your skin or the whites of your eyes (jaundice), stomach pain, feeling unusually tired, and flu-like symptoms - let your doctor know straightaway if you develop any of these.

  • You must avoid getting pregnant while you are taking bosentan because it could cause harm to an unborn baby. Make sure you have discussed with your doctor which types of contraception are suitable for you, as some hormonal contraceptives (such as 'the pill') are not sufficiently reliable. Your doctor will ask you to have a pregnancy test before you start taking bosentan, and then monthly during the treatment.

  • It is possible that bosentan taken long-term reduces fertility in men by lowering the sperm count. Discuss this with your doctor if you have any concerns about it.

  • If you are due to have an operation or some other medical treatment, it is important that you tell the person carrying out the treatment that you are taking bosentan.

  • If you buy any medicines, check with your doctor or a pharmacist that they are suitable for you to take.

  • Keep taking the tablets regularly until your doctor tells you otherwise. Stopping suddenly can cause problems and your doctor may want you to reduce your dose gradually if this becomes necessary.

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Can bosentan cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the more common ones associated with bosentan. The best place to find a full list of the side-effects which can be associated with your medicine, is from the manufacturer's printed information leaflet supplied with the medicine. Alternatively, you can find an example of a manufacturer's information leaflet in the reference section below. Speak with your doctor or pharmacist if any of the following continue or become troublesome.

Very common bosentan side-effects (these affect more than 1 in 10 people)

What can I do if I experience this?


Drink plenty of water and ask your pharmacist to recommend a suitable painkiller. If the headaches continue, speak with your doctor

Swollen feet or ankles, fluid retention

If this becomes troublesome, speak with your doctor

Changes to some blood tests

Your doctor will regularly check for these

Common bosentan side-effects (these affect fewer than 1 in 10 people)

What can I do if I experience this?

Feeling dizzy or faint

Do not drive and do not use tools or machines while affected

Gastric reflux, diarrhoea

Eat simple meals - avoid fatty or spicy food. Drink plenty of water to replace lost fluids

The sensation of having a 'thumping heart' (palpitations), flushing, a stuffy nose

If troublesome, speak with your doctor

Allergic-type reactions such as an itchy red rash

Let your doctor know as soon as possible

If you experience any other symptoms which you think may be due to the tablets, speak with your doctor or pharmacist for further advice.

How to store bosentan

  • Keep all medicines out of the reach and sight of children.

  • Store in a cool, dry place, away from direct heat and light.

Important information about all medicines

Important information about all medicines

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Report side effects to a medicine or vaccine

If you experience side effects, you can report them online through the Yellow Card website.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

  • Next review due: 12 Jan 2026
  • 13 Jan 2023 | Latest version

    Last updated by

    Michael Stewart, MRPharmS

    Peer reviewed by

    Sid Dajani
  • 5 Oct 2013 | Originally published

    Authored by:

    Helen Allen
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