Bosentan, sold under the brand name Tracleer among others, is a dual endothelin receptor antagonist medication used in the treatment of pulmonary artery hypertension (PAH).

[4] Bosentan causes harm to fetuses (teratogenic) and it may render hormonal contraceptives ineffective.

[4][3] Very common adverse effects (occurring in more than 10% of people) include headache, elevated transaminases, and edema.

Common adverse effects (between 1% and 10% of people) include anemia, reduced hemoglobin, hypersensitivity reactions, skin inflammation, itchiness, rashes, red skin, flushing, fainting, heart palpitations, low blood pressure, nasal congestion, gastro-esophageal reflux disease, and diarrhea.

Under normal conditions, endothelin-1 binding of ET-A receptors causes constriction of the pulmonary blood vessels.