Viagra, the trade name and generic name for sildenafil citrate, may be consumed with normal occurrences such as penile erection, or adverse reactions such as dry mouth and flushing. Sildenafil citrate is a kind of drug to treat erectile dysfunction, about one hour after the drug is used, patients may experience body heat, dry mouth, penile erection and other phenomena after receiving sexual stimulation, which is a manifestation of the drug’s effect, there is no need to worry. However, adverse reactions such as headache, flushing, dizziness, nasal congestion, dyspepsia, visual abnormalities, facial edema, shock, malaise, pain, rash, tachycardia, palpitations (rapid heartbeat, often accompanied by panic), low blood pressure, postural hypotension, and other adverse reactions may occur. The drug is prohibited in combination with nitrate drugs, it is contraindicated in women, people who are allergic to the product, children, people whose recent cardiovascular state is not suitable for sexual life. If you need to take sildenafil citrate tablets, you should know whether you are allergic to the components of the drug, and then follow the doctor’s instructions to use the drug, do not blindly use the drug on your own.