Cialis (tadalafil) is a prescription drug intended for effective treatment of sexual disorders, namely erectile dysfunction. It can be caused by a combination of physical or psychological factors. Vision loss is a rare but serious side effect of taking Cialis that in some cases is irreversible. This is why it’s so important to report this symptom to your health care provider as soon as possible. There is not sufficient data on whether this symptom is related to taking Cialis (as other ED medications have the same rare side effect reported), to certain factors (being older than 50, smoking and being diagnosed with high blood pressure, diabetes or high cholesterol levels) or a combination of all the factors. Do not let other people take your medicine and make sure children are unable to access it.