For severe asthma/respiratory distress in adults, what is the magnesium sulfate dose?

• A. 2 gm slow IV drip over 20 minutes. Do not repeat.
• B. 4 gm IV drip over 20 minutes
• C. 2 gm IV push over 5 minutes
• D. 1 gm IV drip over 10 minutes

Answer: (A)

Magnesium sulfate helps relax bronchial smooth muscle and is used as an adjunct in severe asthma to improve bronchodilation when first-line therapies aren’t enough. In adults with severe respiratory distress, the standard dosing is 2 grams given as a slow intravenous infusion over about 20 minutes. This slow infusion minimizes the risk of side effects such as flushing, hypotension, or bradycardia, and many standing orders specify this as a single dose without repetition. A higher dose like 4 grams increases the chance of adverse effects without additional benefit in this setting, a rapid IV push is more likely to cause intolerance, and a smaller dose like 1 gram is typically not sufficient to achieve the desired bronchodilatory effect.