Your doctor or other health care professional can recommend one for you based on these factors, other health conditions you have and any other medicines you take. If you experience chest pain, dizziness, or nausea during sex, seek immediate medical help. You are encouraged to report adverse events related to Viatris products by calling U. You should make an appointment with your doctor to get a prescription before trying to buy Viagra. Your doctor will prescribe whatever he deems is best for you. They include dutasteride Avodart, Jalyn and finasteride Propecia, Proscar.CHOOSE BRAND-NAME VIAGRA. The original little blue pill prescribed by doctors for over 20 years. Clinically proven to treat men with erectile dysfunction (ED) Ongoing . Sildenafil (Viagra). This medicine works best when you take it on an empty stomach an hour before sex. The body takes longer to absorb it after a high-fat meal or alcohol. Its effects often last for 4 to 5 hours. It might work longer if you have mild to moderate erectile dysfunction. Vardenafil. See more.  · Viagra is usually taken only when needed, 30 minutes to 1 hour before sexual activity. You may take it up to 4 hours before sexual activity. Stop taking sildenafil and .