Zestasil 100 Tablet contains Sildenafil 100 mg, a phosphodiesterase type 5 (PDE5) inhibitor used primarily for the treatment of erectile dysfunction (ED) in adult males. Sildenafil facilitates penile erection by enhancing the effects of nitric oxide, which relaxes muscles in the corpus cavernosum and increases blood flow to the penis during sexual stimulation. It is important to note that Zestasil 100 does not induce an erection without sexual arousal. The medication is administered orally, typically 30 minutes to one hour before anticipated sexual activity, and its effects may last up to four to six hours. Dosage should be individualized based on efficacy and tolerability, with a maximum recommended dose of 100 mg per day. Common side effects include headache, flushing, dyspepsia, nasal congestion, and dizziness. Zestasil 100 is contraindicated in patients using nitrates or nitric oxide donors due to the risk of severe hypotension. Caution is advised in patients with cardiovascular disease, hepatic or renal impairment, and those taking other medications that may interact with Sildenafil. Patients should consult a healthcare professional before initiating therapy to ensure safe and appropriate use.