However they can’t charge you for doing so. Read and follow these instructions carefully before you start using sildenafil and each time you get a refill of your medicine. For erectile dysfunction, it’s best to take sildenafil on an empty stomach. The FDA has also approved an injectable medication, bremelanotide Vyleesi , as a treatment for low sexual desire in premenopausal women. Severe liver disease. This medicine works best when you take it on an empty stomach an hour before sex.Drugs and Supplements Sildenafil (Oral Route) Description and Brand Names Before Using Proper Use Precautions Side Effects Products and services Proper Use Drug information . The VIAGRA Savings Card allows eligible patients to save 50% on up to 12 prescriptions of brand-name VIAGRA—and could save up to $4, a year. If you have a prescription for brand-name VIAGRA, you can use the card for every fill through December 31, * *Terms and conditions apply. Sildenafil tablets for erectile dysfunction come in different strengths ranging from 25mg to mg. The usual dose is 50mg, when you need it. Do not take it more than once a day. The dose can be increased to mg or decreased to 25mg depending on its effect. Take sildenafil up to 4 hours before you want to have sex.