Anaphylactic reaction due to other serum, initial encounter

This code signifies a severe, life-threatening allergic reaction (anaphylaxis) triggered by a serum product other than antitetanus serum. This systemic hypersensitivity response involves multiple organ systems and can manifest rapidly after exposure.

Apply this code when documenting an initial episode of anaphylaxis caused by therapeutic serums such as antivenom, botulism antitoxin, or other animal-derived immune globulins. It is appropriate for the first time a patient presents for treatment of this specific adverse event.

• Requires an additional code to identify the specific serum causing the reaction (e.g., T80.89XA for other complications of infusion, transfusion, and therapeutic injection).
• Always assign an external cause code (e.g., Y43.8) to specify the drug or biological substance involved.
• The "A" seventh character indicates an initial encounter for active treatment of the anaphylactic reaction.