When oral medicines might not be safe

Not everyone can safely take oral medicine for erectile dysfunction. These medicines include avanafil (Stendra), sildenafil (Viagra), tadalafil (Cialis) and vardenafil.

Oral medicine for ED might not work or might be dangerous if you already take:

• Nitrate medicines often prescribed for chest pain, also called angina.
• Alpha-blocker medicines commonly prescribed for an enlarged prostate.
• Medicine that affects an enzyme called CYP3A4.

Oral medicine for ED also might not be safe or effective if you have:

• A recent history of heart or blood vessel problems. This includes a heart attack, stroke or a serious heart rhythm disorder in the past six months.
• Very low blood pressure, called hypotension.
• Uncontrolled high blood pressure, called hypertension.
• Severe liver disease.
• An inherited eye disease that affects the retina.
• Kidney disease that needs to be treated with dialysis.

Some people with ED also might choose another treatment so they don't get side effects caused by certain oral medicines.