Your doctor may adjust your dose as needed and tolerated. If you experience a sudden loss of vision in one or both eyes, contact your doctor immediately. This medication is taken with or without food an hour before sex. When choosing one, tell your doctor or other health care professional what your preferences are, such as cost, ease of use, how long the drug’s effects last and side effects. Read and follow these instructions carefully before you start using sildenafil and each time you get a refill of your medicine. Bleeding disorders, history of or Stomach ulcer, or history of or—Chance of problems occurring may be increased. For treatment of erectile dysfunction: For oral dosage form tablets : Adults up to 65 years of age—50 milligrams mg as a single dose no more than once a day, 1 hour before sexual intercourse. · Initial dose: 5 or 20 mg orally three times a day, 4 to 6 hours apart. Maximum dose: 20 mg orally three times a day. Injection: Initial dose: or 10 mg IV bolus three times a day. Comments: No greater efficacy was achieved with oral doses higher than the maximum recommended dose. Examples of Viagra’s more commonly reported side effects include: headache. flushing (temporary warmth, redness, or deepening of skin color) stuffy nose. indigestion (upset stomach) mild vision. The recommended dosage of Viagra for erectile dysfunction (ED) is 50 mg, taken as needed about 1 hour before sexual activity. You can take it 30 minutes to 4 hours before sexual activity. And you.