Viagra is the trade name for the generic name Sildenafil. When taking sildenafil, you usually do not need to drink a lot of water on purpose, and you can just take the medication with the right amount of warm water. Sildenafil is effective in improving erectile dysfunction in men, usually within thirty minutes to one hour after taking the drug. The probability of adverse reactions to the drug is relatively low, and there is no need to take large amounts of water to promote dilution of the drug. Therefore, it is generally not necessary to take the drug with a lot of water. Sildenafil has a chance of causing abnormal erections, which need to be treated promptly or permanent damage to the penis can occur. Sildenafil can also cause sudden vision and hearing loss, so the drug should be used under the supervision of a doctor. As sildenafil can enhance the antihypertensive effect of nitrate, it is forbidden to use the drug while taking nitrate drugs. Patients who are allergic to sildenafil should also not take it. When taking sildenafil, you do not need to drink a lot of water. If you have any discomfort after taking sildenafil, you should go to a professional hospital immediately and have a checkup and treatment under the doctor’s guidance.