Safety information:

Cialis

Do NOT use Cialis if:

you are allergic to any ingredient in Cialis, you have severe kidney problems and will be taking Cialis daily you have severe liver problems or certain hereditary degenerative eye problems (eg, retinitis pigmentosa)... read more

Levitra

Do NOT use Levitra if:

you are allergic to any ingredient in Levitra, you have been advised by your doctor to avoid sexual activity because of heart problems, you have certain heart problems (eg, severe heart failure, angina), low or high blood pressure, severe liver problems or severe kidney problems that require dialysis...read more

Side effects:

Cialis

All medicines may cause side effects, but many people have no, or minor, side effects.Check with your doctor if any of these most common side effects persist or become bothersome:
Dizziness; flushing; headache; heartburn; mild back or muscle pain; stomach upset; stuffy or runny nose... read more

Levitra 

All medicines may cause side effects, but many people have no, or minor, side effects.Check with your doctor if any of these most common side effects persist or become bothersome:
Dizziness; flushing; headache; heartburn; nausea; stuffy or runny nose; upset stomach... read more