Patient instructed on Nitroglycerin sublingual tablets usually give relief in 1 to 5 minutes. If the pain is not relieved, you may use a second tablet 5 minutes after you take the first tablet. If the pain continues for another 5 minutes, a third tablet may be used. If you still have chest pain after a total of 3 tablets, contact your doctor or go to a hospital emergency room right away. Do not drive yourself and call 911 if necessary.