Adverse effect of unsp prim sys and hematolog agent, subs

This code signifies an undesirable or harmful reaction to a medication that affects the body's systems broadly or its blood-forming components, where the specific drug causing the reaction is not documented. The "subsequent encounter" designation indicates that the patient is receiving follow-up care for this adverse effect after the initial treatment.

Apply this code when a patient presents for ongoing management or monitoring of an adverse effect from an unknown systemic or hematological agent. This is appropriate for situations such as a patient returning for a recheck of lab values or symptom management related to a previously identified, but unspecified, drug reaction.

• Ensure the documentation clearly states that the encounter is for follow-up care of the adverse effect, not the initial treatment.
• Only use this code when the specific drug responsible for the adverse effect cannot be identified from the medical record.
• Always sequence this code after the code(s) for the specific manifestation(s) of the adverse effect.