PRECAUTIONS: Tell your doctor your medical history, especially: stomach problems (e.g., colitis), uncorrected low mineral levels in the blood (e.g., potassium and magnesium), asthma or breathing disorders, kidney disease, liver disease, certain heart diseases (cardiac hypertrophy, cardiac conduction conditions - e.g., prolonged QT interval), head injury, seizure disorder, depression, substance abuse problems, any allergies. To avoid dizziness and lightheadedness when rising from a seated or lying position, get up slowly. Avoid intake of alcoholic beverages because it may intensify these effects. Use caution performing tasks requiring alertness if this medication makes you drowsy or dizzy. The elderly may be more sensitive to the effects of methadone. Use with caution. Children may be more sensitive to the effects of methadone. Use with caution. This medication should be used during pregnancy only if clearly needed. Discuss the risks and benefits with your doctor. This medication is excreted into breast milk and may have undesirable effects on a nursing infant. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: Tell your doctor or all prescription and nonprescription drugs you may be using, especially: MAO inhibitors (e.g., furazolidone, linezolid, phenelzine, selegiline, tranylcypromine), psychiatric drugs (e.g., desipramine), tranquilizers, sleeping pills (e.g., zolpidem), zidovudine, didanosine, stavudine, nevirapine, efavirenz, ritonavir, ritonavir/lopinavir, other narcotic pain relievers, drugs which affect certain liver enzymes (CYP 3A4 substrates, inhibitors, and inducers such as St John's wort, cimetidine, azole antifungals--itraconazole, macrolide antibiotics--erythromycin, rifamycins--rifampin, certain anti-seizure medications--phenobarbital, phenytoin, carbamazepine), certain antihistamines (e.g., diphenhydramine) or other drugs which can also cause drowsiness. Other drugs besides methadone which may affect the heart rhythm (QTc prolongation in the EKG) include dofetilide, pimozide, procainamide, quinidine, sotalol, sparfloxacin, "water pills" (diuretics such as furosemide), and laxatives among others. QTc prolongation can infrequently result in serious, rarely fatal, irregular heartbeats. Other symptoms may include unusual dizziness or fainting. Seek immediate medical attention should these occur. Consult your doctor or pharmacist for details. Ask for instructions about whether you need to stop any other QTc-prolonging drugs you may be using in order to minimize the risk of this effect. Check the labels on all your medicines (e.g., cough-and-cold products) because they may contain drowsiness-causing ingredients. Ask your pharmacist about the safe use of these products. Do not start or stop any medicine without doctor or pharmacist approval.