Cialis (tadalafil) is a prescription anti-impotence drug successfully used for millions of men every year helping most of them to achieve harder erections. Before going to visit your other doctor and being prescribed any other medicine make sure you mention the fact of taking Cialis. You may be required to temporarily stop taking this medicine to avoid interactions, or your dosage will need to be adjusted. Serious side effects that should be reported as soon as possible include blurred vision, sudden loss of hearing or vision, chest pain, dizziness, rash, hives, priapism, ringing in the ears. Some other side effects are possible but these are individual for every patient. If you notice any side effects that you think may mean Cialis is not working properly for you, talk to your health care provider.