Phenylephrine, also known as neoforin, mescaline, phenylephrine hydrochloride, etc. Phenylephrine is an alpha-adrenergic receptor stimulant. It mainly increases the resistance of peripheral blood vessels and raises blood pressure. In addition to direct excitation of alpha receptors, it is also able to cause the release of phenylephrine. Its effect is weaker than that of norepinephrine, but it is long-lasting. It can be effective in 10-15 min after intramuscular injection and can be maintained for 1 h. It can be maintained for 20 min after injection and is effective when taken orally. However, the absorption is not too regular, and there is a weak excitatory effect on beta receptors at high doses. In addition, it can be used as a rapid and short-acting pupil dilator for supraventricular paroxysmal tachycardia. Then there is the prevention of hypotension and anaphylaxis during spinal anesthesia. It can also be used for allergic symptoms such as rhinitis and kwashiorkor fever, pupil dilation, and to prolong the action of local anesthetics, among other effects. The above is for reference only. Please refer to the doctor’s face-to-face guidance for specific medication and treatment.