Viagra is the trade name and generic name for Sildenafil Citrate Tablets, this product is taken up to once a day, twice a day may increase liver burden and adverse reactions. Sildenafil citrate tablets are indicated for the treatment of erectile dysfunction, the recommended dosage of this product instruction is 50mg, but based on the efficacy and resistance, the maximum dosage can be up to 100mg or reduced to 25mg, but the maximum dosage is taken once a day. Since the elimination of this product is mainly metabolized by the liver, if taken twice a day, it may increase the burden on the liver and cause damage to the liver. In addition, taking it twice a day may aggravate the adverse reactions with headache, flushing, indigestion, nausea, etc. This product should be contraindicated for those who are allergic to the ingredients contained in this product, or those who are taking any dosage form of nitrate, etc. If there is a need for medication, it is recommended to follow the doctor’s instructions, avoid blindly using the drug or increase the dose, so as not to cause discomfort.