A patient with angina pectoris has been discharged with a new prescription for nitroglycerin tablets. What is the most important instruction for the practical nurse (PN) to emphasize to the patient regarding the administration of nitroglycerin?

Flushing, dizziness, and general body warmth are common occurrences with each sublingual tablet taken.

If chest pain is not relieved after taking one nitroglycerin tablet three times at 5-minute intervals, call the emergency medical service (EMS).

A pounding headache is a common side effect of both the nitroglycerin patch and the sublingual tablets.

Use the nitroglycerin patch for long-term prevention and use the sublingual tablets for acute attacks.