Common side effects of Cialis include dizziness, facial flushing, nasal congestion, and headaches. Some men also report indigestion, back pain, and vision changes. These side effects are usually mild and go away on their own, but you should contact your healthcare provider should they worsen or bother you for more than a week.
Severe side effects are rare with Cialis. However, serious side effects may include sudden vision loss, hearing loss, low blood pressure, and priapism (an erection that lasts longer than four hours). Serious side effects require medical help and prompt treatment. If any of these side effects occur, you'll want to seek medical attention immediately.