Nitroglycerin ointment (Nitro-Bid) is used to:

Nitroglycerin ointment, known by the brand name Nitro-Bid, is primarily used to prevent angina, which is chest pain caused by reduced blood flow to the heart. The active ingredient in this ointment works by relaxing and dilating blood vessels, thereby improving blood flow and reducing the heart's workload. This results in alleviating the episodes of angina that patients might experience due to conditions such as coronary artery disease.

The prevention of angina makes this ointment particularly useful for patients who have a known history of heart issues or angina attacks. By applying the ointment, patients can manage and reduce the frequency and severity of their angina episodes effectively.

Other options such as softening dry skin, treating skin infections, or preventing migraine headaches are not associated with the pharmacological action of nitroglycerin and thus are not relevant to its intended use. The regulation of blood flow and reduction of heart strain through vasodilation is the specific application that distinguishes nitroglycerin ointment in clinical settings.