Before taking disopyramide, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: diabetes, glaucoma, kidney disease, liver problems, myasthenia gravis, urinary problems (such as due to enlarged prostate, urinary retention).

This drug may rarely make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Disopyramide may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away.

The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using disopyramide, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions: certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG), family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death).

Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/"water pills") or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using disopyramide safely.

This drug may cause low blood sugar (hypoglycemia), especially if you have diabetes, heart failure, decreased kidney/liver function, or nutrition problems. Tell your doctor right away if you have symptoms of low blood sugar including sudden sweating, shaking, fast heartbeat, hunger, blurred vision, dizziness, or tingling hands/feet. If you have diabetes, your diabetes medication, exercise program, or diet may need to be adjusted.

Older adults may be more sensitive to the side effects of this drug, especially urination problems and QT prolongation (see above).

During pregnancy, this medication should be used only when clearly needed. Rarely, disopyramide may cause early labor during pregnancy. Discuss the risks and benefits with your doctor.

This medication passes into breast milk, and the effect on a nursing infant is unknown. Consult your doctor before breastfeeding.