Viagra is known generically as sildenafil citrate tablets; 必利勁 is the trade name for dapoxetine hydrochloride tablets. If there is an indication for both drugs then they can be used in combination with caution as prescribed by the doctor. Sildenafil citrate tablets can treat erectile dysfunction in men, and dapoxetine hydrochloride tablets can treat premature ejaculation, and the two generally do not have significant drug interactions, but considering that the use of dapoxetine may result in a reduction of standing endurance, it is necessary to be careful to combine the use of sildenafil citrate tablets. Note that sildenafil citrate tablets should be contraindicated in people who have recently taken guanylate cyclase stimulators and nitrates, and those who are allergic to the product. Adverse drug reactions include indigestion, headache, hot flashes (bouts of fever), nasal congestion, back pain, and myalgia. Dapoxetine hydrochloride tablets should be contraindicated in people who are allergic to the drug, people with moderate or severe liver injury, and people with significant pathological conditions of the heart. Common adverse reactions include nausea, diarrhea, headache, dizziness, insomnia, and fatigue. Specific medications regarding both should be used under the guidance of a specialist.