Sexual activity may put extra strain on your heart especially if you have problems. If you have heart problems and experience any of these serious side effects while having s stop and get medical help right away: severe dizziness,, chest/jaw/left arm pain,

Rarely, sudden decreased, including permanent blindness, in one or both (NAION) may occur. If this serious problem occurs, stop taking sildenafil and get medical help right away. You have a slightly greater chance of developing NAION if you have certain other (“crowded disk”), if you are over 50, or if you smoke.