Viagra generic name is sildenafil citrate tablets, if the drug size is 25 mg, some patients can take 4 pills at a time, but need to follow the doctor’s instructions for medication. Sildenafil citrate tablets are clinically used for the treatment of erectile dysfunction in men, and the recommended dosage for most patients is 50 milligrams, but because of differences in efficacy and tolerability, the dosage can be increased to 100 milligrams (the maximum recommended dosage) in some patients. If the patient’s dosage size is 25 mg, he or she can take 4 pills at a time after a thorough evaluation by the doctor. If sildenafil citrate tablets are available in 50 mg and 100 mg sizes, patients are not allowed to take 4 tablets at a time. In case of Sildenafil Citrate Tablet, some patients may experience adverse reactions such as headache, indigestion and nausea after using the drug. If patients are allergic to this drug, then the drug is contraindicated. During taking Sildenafil Citrate Tablets, combining with nitrates and guanylate cyclase agonists is contraindicated. It is recommended that patients take Sildenafil Citrate Tablets under the guidance of a doctor, and should not use the drug on their own to avoid accidents.