Macitentan is used to manage the symptoms of pulmonary arterial hypertension (PAH; high blood pressure in the vessels that carry blood to the lungs). Macitentan is in a class of medications called endothelin receptor antagonists. It works by stopping the action of endothelin, a natural substance that causes blood vessels to narrow and prevents normal blood flow in people who have PAH.

Side Effects Of Macitentan

Macitentan may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • stuffy nose
  • sore throat
  • cough
  • flu-like symptoms
  • headache
  • urgent, frequent, or painful urination
  • rash

Some side effects can be serious. If you experience any of these symptoms, stop taking macitentan and call your doctor immediately or get emergency medical treatment:

  • itchy skin
  • dark urine
  • yellowing of your skin or eyes
  • pain in the upper right part of your stomach
  • unexplained nausea or vomiting
  • loss of appetite
  • extreme tiredness
  • fever
  • swelling of the face, throat, tongue, lips, and eyes
  • difficulty swallowing or breathing
  • hoarseness
  • shortness of breath, especially when lying down
  • coughing up pink, frothy sputum, or blood
  • unusual weight increase
  • swelling of the ankles or legs

Macitentan may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

Warnings & Precautions

Before taking macitentan:

  • tell your doctor and pharmacist if you are allergic to macitentan, any other medications, or any of the ingredients in macitentan tablets. Ask your pharmacist or check the Medication Guide for a list of the ingredients.
  • tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, and nutritional supplements you are taking or plan to take. Be sure to mention any of the following: carbamazepine (Carbatrol, Epitol, Equetro, Tegretol), clarithromycin (Biaxin, in Prevpac); efavirenz (Sustiva); certain HIV protease inhibitors such as nelfinavir (Viracept), indinavir (Crixivan), and ritonavir (Norvir, in Kaletra); itraconazole (Onmel, Sporanox); ketoconazole; nefazodone; nevirapine Viramune); phenobarbital; phenytoin (Dilantin, Phenytek); rifabutin (Mycobutin); and rifampin (Rifadin, Rifamate, Rifater, Rimactane). Your doctor may need to change the doses of your medications or monitor you carefully for side effects. Many other medications may also interact with macitentan, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list.
  • tell your doctor what herbal products you are taking, especially St. John’s wort.
  • tell your doctor if you have or have ever had anemia (a condition in which red blood cells do not bring enough oxygen to the organs) or liver disease.
  • do not breastfeed while taking this medication.
  • you should know that this medication may decrease fertility in men. Talk to your doctor about the risks of taking macitentan.

Dosage Of Macitentan

Macitentan comes as a tablet to take by mouth. It is usually taken with or without food once a day. Take macitentan at around the same time every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take macitentan exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Swallow the tablets whole; do not split, chew, or crush them.


Keep all appointments with your doctor and the laboratory. Your doctor may order tests to see how well your liver is working, and to check for anemia before starting treatment and from time to time during your treatment with macitentan.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.


All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.