WARNINGS AND PRECAUTIONS

Tolerance
Excessive use may lead to the development of tolerance. Only the smallest dose required for effective relief of the acute angina attack should be used. A decrease in therapeutic effect of sublingual nitroglycerin may result from use of long-acting nitrates.

Hypotension
Severe hypotension, particularly with upright posture, may occur with small doses of nitroglycerin particularly in patients with constrictive pericarditis, aortic or mitral stenosis, patients who may be volume-depleted, or are already hypotensive. Hypotension induced by nitroglycerin may be accompanied by paradoxical bradycardia and increased angina pectoris. Symptoms of severe hypotension (nausea, vomiting, weakness, pallor, perspiration and collapse/syncope) may occur even with therapeutic doses.

Hypertrophic Obstructive Cardiomyopathy
Nitrate therapy may aggravate the angina caused by hypertrophic cardiomyopathy.

Headache
Nitroglycerin produces dose-related headaches, especially at the start of nitroglycerin therapy, which may be severe and persist but usually subside with continued use.