Isosorbide is used to prevent or treat chest pain (angina). It works by relaxing the blood vessels to the heart, so the blood and oxygen supply to the heart is increased.

This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

Isosorbide comes as a regular, sublingual, chewable, and extended-release (long-acting) tablet and extended-release (long-acting) capsule to be taken by mouth. The tablet usually is taken every 6 hours. The extended-release tablet usually is taken one or two times a day. The extended-release capsule usually is taken every 8-12 hours. Do not crush, chew, or divide the extended-release tablets or capsules. The sublingual or chewable tablet is used as needed to relieve chest pain that has already started or to prevent pain before activities known to provoke attacks (e.g., climbing stairs, sexual activity, heavy exercise, or being outside in cold weather). The chewable tablet also may be used every 2-3 hours to prevent chest pain. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take isosorbide exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Isosorbide controls chest pain but does not cure it. Continue to take isosorbide even if you feel well. Do not stop taking isosorbide without talking to your doctor. Stopping the drug abruptly may cause chest pain.

Isosorbide can lose its effectiveness when used for a long time. This effect is called tolerance. If your angina attacks happen more often, last longer, or are more severe, call your doctor.

If you are using isosorbide sublingual or chewable tablets for acute chest pain, you should carry the tablets with you at all times. If you are taking isosorbide and your chest pain is not relieved within 5-10 minutes, take another dose. Call for emergency assistance or go to a hospital emergency department if pain persists after you have taken three tablets (at 5-10-minute intervals) and 15-30 minutes have passed.

When an attack occurs, sit down. If you use chewable tablets, chew a tablet thoroughly and swallow it. To use the sublingual tablets, place a tablet under your tongue or between your cheek and gum and allow it to dissolve. Do not swallow the tablet. Try not to swallow saliva too often until the tablet dissolves.

SIDE EFFECTS, that may go away during treatment, include headache, dizziness, or nausea. If they worsen, continue, or are bothersome, check with your doctor. If you notice other effects not listed above, contact your doctor, nurse, or pharmacist.

If overdose is suspected, contact your local poison control center or emergency room immediately. Symptoms of overdose may include throbbing headache, confusion, dizziness, perspiring skin, nausea, vomiting, difficulty breathing, slow pulse, and loss of consciousness.

DO NOT SHARE THIS MEDICINE with others for whom it was not prescribed. DO NOT USE THIS MEDICINE for other health conditions. KEEP THIS MEDICINE out of the reach of children. IF USING THIS MEDICINE FOR AN EXTENDED PERIOD OF TIME, obtain refills before your supply runs out.

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

This medicine is a vasodilator used to prevent angina (chest pain).

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Keep sublingual and chewable tablets in the original container. Do not open a container of sublingual or chewable isosorbide until you need a dose. Do not use tablets that are more than 12 months old. Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

DO NOT STOP TAKING THIS MEDICINE without first discussing it with your doctor. Stopping suddenly may bring on an angina attack. THIS MEDICINE MAY cause dizziness or lightheadedness. This may be especially noticeable after getting up from a lying or sitting position. Drinking alcohol with this medicine will add to this effect. Do not drive, operate machinery, or do anything else that could be dangerous until you know how you react to this medicine. WHEN YOU BEGIN USING THIS MEDICINE, headaches are likely to occur. Ask your doctor for instructions on ways to reduce this side effect. FOR MEN: DO NOT TAKE VIAGRA (sildenafil) while using this medicine. FOR WOMEN: IF YOU PLAN ON BECOMING PREGNANT, discuss with your doctor the benefits and risks of using this medicine during pregnancy. IT IS UNKNOWN IF THIS DRUG IS EXCRETED in breast milk. IF YOU ARE OR WILL BE BREAST-FEEDING while you are using this medicine, check with your doctor or pharmacist to discuss the risks to your baby.