Allergy, unspecified, sequela

This code signifies a long-term or residual effect stemming from a past allergic reaction, where the specific type of allergy is not documented. It indicates that a patient is experiencing a health problem that is a direct consequence of an allergic event that occurred previously.

This code is appropriate when a patient presents with a chronic condition or complication clearly attributed to an unspecified allergic reaction that has since resolved. Examples include persistent organ damage or chronic inflammatory responses linked to a past allergic episode, but the allergen itself was never identified or documented.

• Always assign a secondary code to describe the specific sequela (e.g., chronic asthma, dermatitis).
• Ensure documentation clearly links the current condition to a past allergic event.
• Avoid using this code for acute allergic reactions or when the specific allergen is known.