Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
During sexual activity, if you become dizzy or nauseated, or have pain, numbness, or tingling in your chest, arms, neck, or jaw, stop and call your doctor right away. You could be having a serious side effect of sildenafil.
Stop using sildenafil and call your doctor at once if you have a serious side effect such as:
- sudden vision loss;
- ringing in your ears, or sudden hearing loss;
- chest pain or heavy feeling, pain spreading to the arm or shoulder, nausea, sweating, general ill feeling;
- irregular heartbeat;
- swelling in your hands, ankles, or feet;
- shortness of breath;
- vision changes;
- feeling light-headed, fainting; or
- penis erection that is painful or lasts 4 hours or longer.
Less serious side effects may include:
- warmth or redness in your face, neck, or chest;
- stuffy nose;
- memory problems;
- upset stomach; or
- back pain.
This is not a complete list of side effects and others may occur.