Make sure you tell your doctor if you have any other medical problems, especially: Abnormal penis, including a curved penis or birth defects of the penis—Chance of problems occurring may be increased and this medicine should be used with caution in these patients. These include itraconazole Sporanox, Tolsura , ketoconazole Extina, Ketozole, others and ritonavir Norvir. A small placebo-controlled week study performed on men with erectile dysfunction used the Self Esteem and Relationship SEAR questionnaire to assess the impact of sildenafil treatment on patients. However the dose is usually not more than 40 mg 3 times a day. Its use is not studied in patients with severe hepatic impairment. Epistaxis was not observed in patients with idiopathic PAH.Oral Tablet 20 mg sildenafil oral tablet from $ for 10 tablets 25 mg sildenafil oral tablet from $ for 30 tablets 50 mg sildenafil oral tablet from $ for 15 tablets . Sildenafil is used to treat erectile dysfunction (ED) and to reduce blood pressure in pulmonary arterial hypertension (PAH). It is taken when needed for ED and daily for PAH. A headache, stomach upsets, and flushing are the main side effects, and it should not be taken within 24 hours of a nitrate. 5. Tips. Sildenafil is a generic drug, which is an exact copy of the active drug in a brand-name medication. The generic is considered to be as safe and effective as the original drug. And generics tend to.