Ambrisentan: What It Does and How to Use It

If you’ve been prescribed ambrisentan for pulmonary arterial hypertension (PAH), this short guide will help you understand what the drug does, how to take it, and the main safety checks you need. Ambrisentan is an endothelin receptor antagonist — it blocks a substance called endothelin‑1 that tightens blood vessels in the lungs. By lowering that signal, the medicine eases pressure in the pulmonary arteries and can improve your ability to exercise and breathe easier.

How to take ambrisentan safely

Most people start at 5 mg once a day, and some move up to 10 mg daily if tolerated. Take it the same time each day, with or without food, unless your doctor says otherwise. It’s prescription-only, so never buy from an unverified online seller.

Before you start, your provider will usually run baseline tests: a pregnancy test for people who can get pregnant, liver tests (ALT/AST), and a hemoglobin level. You’ll need monthly pregnancy tests during treatment and for a month after stopping because ambrisentan can harm a fetus. Liver and blood tests are repeated on a schedule your clinic sets — this helps spot problems early.

Tell your doctor about other meds you take. Some drugs can change ambrisentan levels (for example, certain strong enzyme inhibitors), and other PAH meds may be combined with it but require close monitoring. If you have severe liver disease, ambrisentan may not be safe for you.

Common side effects and when to call your doctor

Watch for swelling in your legs or hands (peripheral edema), nasal congestion, headache, flushing, and feeling tired. Ambrisentan can also lower hemoglobin, so your doctor will check your blood counts. Serious but less common issues include worsening liver function and signs of heart failure or severe fluid buildup.

Call your provider right away if you notice yellowing of the skin or eyes, dark urine, severe belly pain, fainting, sudden worsening shortness of breath, or if you become pregnant while on the drug. These need prompt attention.

Practical tips: keep a list of your meds and bring it to every visit; fill prescriptions at a licensed pharmacy; set monthly reminders for required tests; and ask your clinic about any financial assistance programs if cost is a concern.

Ambrisentan can meaningfully help people with PAH when used correctly and monitored closely. If you’re unsure about dosing, side effects, or interactions, ask your doctor or pharmacist — getting clear answers early prevents trouble later.