VIAGRA is a prescription medication, so you'll need to talk to your healthcare provider to find out if it's right for you. Be sure to ask your healthcare provider if your heart is healthy enough to handle the extra strain of sexual activity. If you have chest pains, dizziness, or nausea during sex, stop and immediately tell your healthcare provider. With VIAGRA, the most common side effects are headache, facial flushing, and upset stomach. VIAGRA may also briefly cause bluish or blurred vision, or sensitivity to light. In the rare event of an erection lasting more than 4 hours, seek immediate medical help. Remember to protect yourself and your partner from sexually transmitted diseases.