Quinidine is used to help keep the heart beating normally in people with certain heart rhythm disorders, usually after other treatments have failed. Quinidine has not been proven to lower the risks of stroke or death.

Quinidine is also used to treat a life-threatening form of malaria.

Quinidine may also be used for purposes not listed in this medication guide.

quinidine may increase your risk of death, especially if you have heart problems affecting the tissues or valves of your heart (including heart problems you may have been born with). Ask your doctor about the risks and benefits of using quinidine.

Quinidine comes as a tablet (quinidine sulfate) and an extended-release (long-acting) tablet (quinidine gluconate) to take by mouth. Quinidine sulfate tablets are usually is taken every 6 hours. Extended-release quinidine gluconate tablets are usually is taken every 8 to 12 hours. Take quinidine at around the same times every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take quinidine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

The extended-release tablet may be split in half. Swallow the whole or half tablets whole; do not chew or crush them.

Quinidine helps control your condition but will not cure it. Continue to take quinidine even if you feel well. Do not stop taking quinidine without talking to your doctor.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed. Your blood pressure and heart rate should be monitored in a hospital or clinic setting when you start using quinidine, and whenever your dose is changed.

Do not change your medication dose or schedule without your doctor's advice.

Quinidine oral is taken by mouth. Quinidine injection is given as an infusion into a vein. A healthcare provider will give you this injection if you are unable to take the medicine by mouth.

Do not crush or chew an extended-release tablet. Swallow it whole. You may break the tablet in half if your doctor instructs you to.

When quinidine is given to treat malaria, you may also be given antibiotic medication. Keep using the antibiotic for as long as your doctor has prescribed.

Store at room temperature away from moisture and heat.

Although quinidine can reduce episodes of irregular heart rhythm, this medicine may increase your risk of death. Your risk may be higher if you have heart problems affecting the tissues or valves of your heart (including heart problems you may have been born with). Ask your doctor about the risks and benefits of using quinidine.

You should not use quinidine if you are allergic to it, or if you have:

• a serious heart condition called "AV block" (unless you have a pacemaker);

• myasthenia gravis; or

• a history of bruising or bleeding after using quinidine or quinine.

Tell your doctor if you have ever had:

• a heart condition called "sick sinus syndrome";

• slow heartbeats;

• congestive heart failure;

• a heart valve disorder, a hole in your heart, an enlarged heart, or mitral valve prolapse;

• long QT syndrome (in you or a family member);

• Marfan syndrome;

• heart rhythm problems with past use of quinidine;

• liver or kidney disease; or

• an electrolyte imbalance (such as low levels of potassium or magnesium in your blood).

It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

You should not breastfeed while using quinidine.

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

Because you will receive quinidine injection in a clinical setting, you are not likely to miss a dose.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of quinidine can be fatal.

Overdose can cause vomiting, diarrhea, ringing in your ears, hearing loss, severe dizziness, double vision, confusion, irregular heartbeats, or feeling like you might pass out.

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).

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

Do not drink grapefruit juice while taking this medication. Do not change the amount of salt in your diet without talking to your doctor.

Grapefruit may interact with oral quinidine and lead to unwanted side effects. Avoid the use of grapefruit products.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Quinidine may cause serious side effects. Call your doctor at once if you have:

• fast or pounding heartbeats, fluttering in your chest, shortness of breath, and sudden dizziness (like you might pass out);

• vomiting and diarrhea;

• confusion, ringing in your ears, hearing loss;

• severe eye redness, vision problems, increased sensitivity to light;

• wheezing, chest tightness, trouble breathing;

• easy bruising, unusual bleeding;

• pale or yellowed skin, stomach pain (upper right side), dark urine;

• fever, chills, sore throat, mouth sores, swollen glands;

• skin itching, flaking, blistering, peeling, or rash on your cheeks or arms that worsens in sunlight;

• muscle or joint pain; or

• dry mouth, trouble swallowing.

Common side effects of quinidine may include:

• chest pain, pounding heartbeats;

• dizziness;

• heartburn, nausea, vomiting, diarrhea;

• flushing (sudden warmth, redness, or tingly feeling);

• feeling weak or tired; or

• pain or tenderness where the medicine was injected (may last for several weeks).

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Sometimes it is not safe to use certain medications at the same time. Some drugs can affect your blood levels of other drugs you take, which may increase side effects or make the medications less effective.

Many drugs can affect quinidine. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here. Tell your doctor about all your current medicines and any medicine you start or stop using.

Keep all appointments with your doctor and the laboratory. Your doctor will need to determine your response to quinidine.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.