Fildena 150 Read the patient information leaflet provided by your pharmacist before you start taking sildenafil and each time you get a refill. If you have any further questions, ask your doctor or pharmacist.To treat erectile dysfunction-ED, take this medication by mouth as directed by your doctor, usually as needed. Take sildenafil at least 30 minutes, but no more than 4 hours, before s*xual activity (1 hour before is most effective). Do not take more than once a day.A high-fat meal can slow down how quickly the medicine starts to work.Dosage is based on your medical condition, response to treatment, and other medications you are taking. Be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, non-prescription drugs, and herbal products).Tell your doctor if your condition does not improve.