It is okay to take sildenafil once a week, please take it regularly as prescribed by your doctor. As the world’s first type 5 phosphodiesterase inhibitor, sildenafil is the drug of choice for the treatment of erectile dysfunction (ED), which is easy to use, safe and effective. Sildenafil can be taken on an as-needed basis, with 50mg/100mg being sufficient 0.5 hours to 1 hour before sex, or it can be taken on a regular basis, with the recommended dosage being 2 times per week for a total of 16 doses (8 weeks). Regardless of the regimen with which it is taken, the drug should not exceed a single daily dose of 100mg. In the clinical use of sildenafil, the ED population showed improvements in erectile function of 56%, 77%, and 84% after 24 weeks of using sildenafil citrate in different dosage forms of 25mg, 50mg, and 100mg, respectively. Sildenafil is prohibited in combination with nitrates (e.g., nitroglycerin), and is contraindicated in sildenafil-hypersensitive individuals and users of guanylate cyclase agonists (e.g., linaclotide). Adverse effects of sildenafil mainly include headache, flushing, dyspepsia, nasal congestion and so on. Specific use should be under the supervision of a clinician to avoid adverse events.