What is the IV bolus dose range for phenylephrine?

• A. 5-10 mcg
• B. 50-100 mcg
• C. 200-400 mcg
• D. 1-2 mg

Answer: (B)

Phenylephrine raises blood pressure mainly by constricting blood vessels through alpha-1 receptor activation. Because it is very potent, the IV bolus is given in micrograms to allow precise, rapid effect without overshooting. The typical bolus range to promptly correct hypotension is 50–100 mcg. A dose of 5–10 mcg is usually too small to achieve a meaningful rise in pressure quickly, while 200–400 mcg or 1–2 mg can cause excessive vasoconstriction and hazards like severe hypertension and reflex bradycardia. In practice, you administer about 50 mcg, reassess, and repeat every 1–2 minutes as needed, titrating to the desired blood pressure.