Macitentan and tadalafil is a combination medicine used in adults to treat pulmonary arterial hypertension (PAH), which causes high blood pressure in the lungs.

Macitentan and tadalafil is available only under a special program. You must be registered in the program and understand the risks and benefits of this medicine.

Macitentan and tadalafil may also be used for purposes not listed in this medication guide.

You should not take macitentan and tadalafil if you are allergic to it, or if you use other medicines to treat pulmonary arterial hypertension, such as riociguat (Adempas).

Do not take macitentan and tadalafil if you are also using certain medicines for chest pain or heart problems called nitrates. These include nitroglycerin, isosorbide dinitrate, and isosorbide mononitrate. Nitrates are also found in some recreational drugs such as amyl nitrate, butyl nitrate or nitrite ("poppers"). Taking this medicine with a nitrate can cause a sudden and serious decrease in blood pressure.

Some macitentan and tadalafil can remain in your bloodstream for 2 or more days after each dose you take (longer if you have liver or kidney disease). Avoid nitrate use during this time.

Tell your doctor if you have or have ever had:

• heart problems (chest pain, a heart rhythm disorder, congestive heart failure);
• a heart attack or stroke;
• low blood pressure;
• retinitis pigmentosa (an inherited condition of the eye);
• problems with hearing or vision;
• a blood cell disorder such as sickle cell anemia, multiple myeloma, or leukemia;
• anemia (low red blood cells);
• pulmonary veno-occlusive disease (PVOD);
• priapism (an erection that is painful or lasts longer than 4 hours);
• a penis deformity (such as Peyronie's disease);
• a stomach ulcer;
• liver disease; or
• kidney disease (or if you are on dialysis).

You will need to take a pregnancy test before, during, and after treatment with macitentan and tadalafil.

May cause birth defects. Do not use if you are pregnant. You must use effective birth control while using macitentan and tadalafil and for at least 30 days after your last dose. Tell your doctor if you become pregnant.

It may be harder for you to get a woman pregnant while you are using this medicine.

Do not breastfeed.

Use Macitentan And Tadalafil (Oral) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Call your doctor at once if you have:

• severe vision problems, including sudden vision loss;
• ringing in your ears or sudden hearing loss;
• a light-headed feeling, like you might pass out;
• a painful erection or one that lasts longer than 4 hours;
• low red blood cells (anemia)--pale skin, tiredness, feeling light-headed or short of breath, cold hands and feet;
• symptoms of liver problems--loss of appetite, pain or swelling in your stomach, swelling in your legs, easy bleeding, drowsiness, confusion, or jaundice (yellowing of the skin or eyes);
• fluid retention--shortness of breath (even while lying down), swelling, rapid weight gain (especially in your face and midsection); or
• heart attack symptoms--chest pain or pressure, pain spreading to your jaw or shoulder, nausea, sweating.

Common side effects may include:

• fluid retention;
• anemia; or
• headache, migraine headache.

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.

Avoid drinking alcohol. Alcohol can further lower your blood pressure and may increase your risk of headache, dizziness, or fainting.

Avoid getting up too fast from a sitting or lying position, or you may feel dizzy.

Grapefruit may interact with macitentan and tadalafil and cause side effects. Avoid consuming grapefruit products.