It's important to note that Caverta 100 mg should only be taken as prescribed by a healthcare professional. Taking higher dosages without medical supervision can increase the risk of side effects and complications. Common side effects of sildenafil citrate may include headache, flushing, indigestion, nasal congestion, and dizziness. In rare cases, more serious side effects such as priapism (a prolonged and painful erection lasting more than four hours) or sudden loss of vision or hearing may occur.