When taken at the correct time and paired with sexual stimulation, the erection lasts long enough for successful intercourse. Payment options: Consider how you’d like to pay. Make sure you have discussed any other medications you are currently taking or plan to take before starting sildenafil with your doctor and pharmacist. Before starting, stopping, or changing any medications while taking sildenafil, please get the advice of your doctor or pharmacist. According to the FDA, generic medications contain the same active ingredients as brand names, meaning there’s no difference in effectiveness or safety. It’s available in 10 mg and 20 mg tablets.Viagra Dosage and Use Tips for First-Timers. Viagra dosage for erectile dysfunction (ED) is usually milligrams (mg), but those over 65 may start at 25 mg. Your doctor will also need to.  · How GoodRx Works. Compare prices. Drug prices vary by pharmacy. Use GoodRx to find current prices and discounts. Get free coupons. GoodRx coupons can help you pay less than the cash price for your prescription. Show to your pharmacist. It’s easy. Just bring your free coupon to the pharmacy when picking up your prescription.  · Viagra comes as an oral tablet that contains the active drug sildenafil. Sildenafil is also available in generic form. Viagra is classified as a phosphodiesterase type 5 (PDE5) inhibitor.