If you experience chest pain, dizziness, or nausea during sex, seek immediate medical help. The most common side effects of VIAGRA: headache; flushing; upset stomach; abnormal vision, such as changes in color vision such as having a blue color tinge and blurred vision; stuffy or runny nose; back pain; muscle pain; nausea; dizziness; rash. United States Sildenafil is available as a generic drug in the United States, labeled for pulmonary arterial hypertension. People with heart conditions should never take ED medications without consulting a doctor. The information provided is for educational purposes only and is not intended to replace discussions with a healthcare provider.Get sildenafil for as low as $, which is 95% off the average retail price of $ for the most common version, by using a GoodRx coupon. Prices Medicare Drug Info Side . Drug details Here are some details on sildenafil: Drug class: phosphodiesterase type 5 (PDE5) inhibitor Drug forms: oral tablet, liquid suspension, intravenous (IV) bolus . Typical dosing for Sildenafil (Viagra) The typical dose is to take 50 mg of sildenafil (Viagra) by mouth, about 1 hour before sex, as needed. The maximum recommended dose is .