Its use is not studied in patients with severe hepatic impairment. Children younger than 1 year of age—Use and dose must be determined by your doctor. However the dose is usually not more than 40 mg 3 times a day. Pediatric Patients: Increased mortality with increasing sildenafil dose was observed in a clinical trial of pediatric patients with PAH. Patients should always ask their doctors for medical advice about adverse events.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 available as oral tablets of 25 mg, 50 mg, and mg strength for erectile dysfunction (ED). Most patients receive a prescription for 50 mg of oral sildenafil, taken as needed approximately 1 hour before sexual activity. The dose can be titrated upward to a maximum of mg or down to 25 mg based on individual . your treatment plan your insurance coverage the pharmacy you use whether Viagra has a savings program (see the “Financial and insurance assistance” section .