Adverse effect of penicillins, initial encounter

This code signifies an undesirable or harmful reaction experienced by a patient due to the therapeutic use of a penicillin-based antibiotic. This adverse effect is not an allergic reaction but rather a side effect or toxicity from the drug itself, occurring during the initial period of treatment.

Apply this code when a patient presents with symptoms such as nausea, diarrhea, or kidney dysfunction directly attributable to penicillin administration, and this is the first time the adverse effect is being documented for this specific course of treatment. It is appropriate for situations where the penicillin was correctly prescribed and administered, but the patient still experienced a negative outcome.

• Always sequence this code after the primary diagnosis for which the penicillin was prescribed.
• Distinguish carefully between an adverse effect (T36.0X5A) and a true allergic reaction (T36.0X3A).
• Ensure documentation clearly states the reaction is an "adverse effect" and not an "allergy" to support this code.