Silfenadil Oral belongs to the class of Phosphodiesterase (PDE) Inhibitors. This medicine is prescribed for the treatment of Erectile Dysfunction (ED). It increases the blood flow in penis and causes erection upon sexual stimulation. Moreover, this drug enhances the ability of an adult to exercise with Pulmonary Arterial Hypertension (PAH). The side effects of Silfenadil Oral include - Nausea and vomiting - Headache - Runny nose and sore throat - Trouble sleeping - Nose bleeds - Respiratory infection - Extra long duration of erection - Weakness - Light headedness - Visual disturbances Silfenadil Oral interacts with the following drugs. - Drugs for blood pressure e.g. Amiodipine - Anti-Fungals e.g. Itroconazole, Ketoconazole - Antibiotics e.g. Erythromycin, Clarithromycin, - Drugs for HIV e.g. Ritonavir, Indinavir