Treprostinil is primarily used in the treatment of pulmonary arterial hypertension (PAH), a condition characterized by high blood pressure in the arteries of the lungs. It helps to improve exercise capacity and reduce symptoms by dilating these arteries, thereby easing the workload on the heart.

It is administered in various forms, including intravenous, subcutaneous, oral, and inhaled routes, allowing flexibility based on patient needs and tolerability. The subcutaneous and intravenous forms are often used for severe cases, while the oral and inhaled forms provide convenience for long-term management.

Additionally, treprostinil is sometimes used off-label for other conditions involving poor blood flow, such as certain types of chronic thromboembolic pulmonary hypertension (CTEPH) or Raynaud's phenomenon. Its vasodilatory and antiplatelet properties make it beneficial in improving blood circulation and reducing complications associated with these conditions.

Patients using treprostinil require careful monitoring due to potential side effects, such as headache, nausea, jaw pain, and site reactions (for injectable forms). Despite these challenges, it remains a vital therapeutic option for improving quality of life in PAH patients.