Adverse effect of methadone, initial encounter

This code signifies an undesirable or harmful reaction experienced by a patient due to the therapeutic use of methadone. This reaction is not an overdose but rather an expected or unexpected side effect when the drug is administered correctly. It indicates the patient is receiving initial treatment for this adverse effect.

Apply this code when a patient presents for the first time with symptoms directly attributable to an adverse effect of prescribed or properly administered methadone. Examples include severe constipation, respiratory depression (not due to overdose), or cardiac arrhythmias occurring during the initial phase of managing the adverse reaction.

• Always sequence this code first if it is the primary reason for the encounter.
• Requires an additional code to identify the specific manifestation of the adverse effect (e.g., R06.02 for respiratory depression).
• Distinguish carefully from poisoning (T40.3X1-) or underdosing (T40.3X6-).