Bleeding disorders, history of or Stomach ulcer, or history of or—Chance of problems occurring may be increased. If you experience chest pain, dizziness, or nausea during sexual activity, call your doctor immediately and avoid sexual activity until your doctor tells you otherwise. Some medications should not be taken with sildenafil. Dosing The dose of this medicine will be different for different patients. If you become pregnant while taking sildenafil, call your doctor. Children younger than 1 year of age—Use and dose must be determined by your doctor. What should I do if I forget a dose?If you have these symptoms, stop taking VIAGRA and contact a doctor right away. have or have had heart problems such as a heart attack, irregular heartbeat, angina, chest pain, narrowing of the aortic valve, or heart failure. have low blood pressure, or high blood pressure that is not controlled. Viagra (sildenafil) is a brand-name oral tablet prescribed for erectile dysfunction. The cost of the drug with and without insurance can depend on several . Viagra (sildenafil) is a prescription drug that’s used to treat erectile dysfunction (ED). The drug comes as a tablet you’ll take by swallowing. It’s usually taken as needed about 1 hour.