Get emergency medical help if you have signs of an allergic reaction to drug: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Stop taking sildenafil and get emergency medical help if you have:
- heart attack symptoms–chest pain or pressure, pain spreading to your jaw or shoulder, nausea, sweating;
- vision changes or sudden vision loss; or
- erection is painful or lasts longer than 4 hours (prolonged erection can damage the penis).
Common side effects may include:
- flushing (warmth, redness, or tingly feeling);
- headache, dizziness;
- abnormal vision (blurred vision, changes in color vision)
- runny or stuffy nose, nosebleeds;
- sleep problems (insomnia);
- muscle pain, back pain; or
- upset stomach.
This is not a complete list of side effects and others may occur.