Which of the following is a contraindication for nitroglycerin use?

• A. Hypotension
• B. Dehydration
• C. Asthma
• D. Allergic to penicillin

Answer: (A)

Nitroglycerin works by dilating veins and arteries, which lowers preload and afterload and reduces the heart’s demand for oxygen. The biggest risk from giving nitroglycerin is causing a dangerous drop in blood pressure. If a patient is already hypotensive, adding nitroglycerin can lead to syncope, inadequate organ perfusion, or shock. That’s why hypotension is a contraindication.

Dehydration isn’t an absolute contraindication, though severe dehydration can contribute to low blood pressure and may worsen effects if nitroglycerin is given. Asthma isn’t a contraindication for nitroglycerin, and an allergy to penicillin has no bearing on nitroglycerin use. In practice, always check blood pressure before administration and withhold if the patient is hypotensive or has signs of low perfusion.