Taking sildenafil once every ten days is generally harmless for adult men who take a reasonable dose of the drug (single <100 mg) and have no contraindications to the drug. Sildenafil is a first-line drug for the treatment of erectile dysfunction (ED) and is convenient, safe and effective. The drug can be taken as needed 30 minutes to 4 hours before sex; it can also be taken regularly. Taking sildenafil once every ten days is part of the on-demand dosing regimen, and is harmless to healthy adult males in the absence of contraindications, the absence of other underlying medical conditions, and a reasonable dosage of the drug. The main adverse reactions when using the drug are blushing, indigestion, nasal congestion, headache. It should also be noted that the drug is contraindicated in people who are allergic to the drug, those who have already used guanylate cyclase agonists (for example, linaclotide). At the same time, the drug is strictly prohibited in combination with nitrates (nitroglycerin). The drug is contraindicated in women, children, and people with recent cardiovascular conditions who should not be sexually active. Specific use should follow the instructions of the clinician to avoid adverse events.