Moderate methadone cimetidine Applies to: methadone and Tagamet (cimetidine)

Cimetidine may increase the blood levels and effects of methadone. You may need a dose adjustment or more frequent monitoring by your doctor to safely use both medications. Contact your doctor if you experience increased side effects such as excessive drowsiness, tiredness, confusion, disorientation, nausea, vomiting, and shallow or difficult breathing. High blood levels of methadone can also occasionally cause an irregular heart rhythm that may be serious. You should seek immediate medical attention if you develop sudden dizziness, lightheadedness, fainting, shortness of breath, or fast or pounding heartbeats. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

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