Adverse effect of barbiturates, initial encounter

This code signifies an undesirable or harmful reaction experienced by a patient due to the therapeutic use of a barbiturate medication. This reaction is not an overdose, but rather an unintended side effect occurring at a standard or prescribed dosage. It represents the first time the patient is being treated for this specific adverse effect.

Apply this code when a patient presents with symptoms such as drowsiness, confusion, ataxia, or skin rash, and these symptoms are directly attributed to a prescribed barbiturate. This is appropriate for the initial visit where the adverse effect is diagnosed and treatment begins. Do not use for intentional poisoning or overdose.

• Ensure documentation clearly states the reaction is an "adverse effect" and not an overdose or poisoning.
• Always sequence this code after the code for the specific manifestation of the adverse effect (e.g., R40.0 for somnolence).
• Verify the encounter is indeed the "initial encounter" for this specific adverse effect; subsequent encounters would use the appropriate seventh character.