Skip to main content


Generic name: ambrisentanAM-bri-SEN-tan ]
Drug class: Agents for pulmonary hypertension

Medically reviewed by Philip Thornton, DipPharm. Last updated on Sep 11, 2023.

What is Letairis?

Letairis prevents thickening of the blood vessels, especially those in the lungs and heart. Ambrisentan also lowers blood pressure in your lungs, helping your heart pump blood more efficiently.

Letairis is used to treat pulmonary arterial hypertension (PAH) in adults. It improves your ability to exercise and prevents your condition from getting worse.

Letairis is sometimes used with a medicine called tadalafil (Adcirca).

For women, Letairis is available only from a certified pharmacy under a special program. You must be registered in the program and sign agreements to use birth control and undergo pregnancy and blood testing.


Letairis can harm an unborn baby or cause birth defects. Do not use if you are pregnant. You will need to take a pregnancy test before, during, and after treatment with ambrisentan.

If you are a woman of child-bearing potential, you will be required to use two forms of birth control to prevent pregnancy during your treatment, and for at least 1 month after your treatment ends.

You should not use Letairis if you have idiopathic pulmonary fibrosis.

Before taking this medicine

You should not use Letairis if you are allergic to ambrisentan, or if you have idiopathic pulmonary fibrosis (IPF).

Do not use Letairis if you are pregnant or think you might be pregnant. This medicine can cause serious birth defects. Tell your doctor right away if you miss a menstrual period or think you may have become pregnant.

You will need to have a negative pregnancy test before starting this treatment. You will be re-tested every month during your treatment, and 1 month after your last dose.

Even if you are not planning a pregnancy, you are considered able to become pregnant if:

While taking Letairis and for at least 30 days after your last dose, you must use a highly effective form of birth control or two methods together.

Recommended forms of birth control forms include:

Letairis comes with patient instructions about acceptable forms of birth control to use while taking this medicine. Follow these directions carefully. Ask your doctor about emergency contraception if you have unprotected sex or if you believe your contraception has failed.

To make sure Letairis is safe for you, tell your doctor if you have ever had:

You should not breastfeed while you are using ambrisentan.

Ambrisentan may lower a man's sperm count and could affect fertility (your ability to have children).

How should I take Letairis?

Letairis is usually taken once daily. Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Before you start treatment with Letairis, your doctor may perform blood tests to make sure it is safe for you to take this medicine. Your blood will need to be tested often during treatment.

Letairis can be taken with or without food. Take the medicine at the same time each day.

Do not crush, chew, or split the tablet. Swallow the pill whole.

Store at room temperature away from moisture and heat. Keep this medicine in its original container.

Dosing information

Usual Adult Dose for Pulmonary Hypertension:

Initial dose: 5 mg orally once a day.

-Consider increasing the dose to 10 mg orally once a day if 5 mg is tolerated.
-When used with tadalafil, the dose of either drug can be increased as needed and tolerated at 4-week intervals.

-For the treatment of pulmonary arterial hypertension (WHO Group 1) to improve exercise ability and delay clinical worsening.
-For the treatment of pulmonary arterial hypertension (WHO Group 1) in combination with tadalafil to reduce the risks of disease progression and hospitalization for worsening pulmonary arterial hypertension, and to improve exercise ability.

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while using Letairis?

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

Letairis side effects

Get emergency medical help if you have signs of an allergic reaction to Letairis: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

Common Letairis side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Letairis?

Tell your doctor about all your other medicines, especially:

This list is not complete. Other drugs may interact with ambrisentan, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Letairis only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.