Poisoning by unspecified agent primarily affecting skin and mucous membrane

This code signifies an adverse reaction to an unknown substance that predominantly manifests with dermatological or mucosal symptoms. It indicates a systemic or localized toxic effect where the causative agent cannot be identified. The patient presents with signs such as rash, urticaria, angioedema, blistering, or inflammation of mucous membranes.

Use this code when a patient presents with symptoms of poisoning primarily affecting the skin and/or mucous membranes, and the specific toxic agent is not documented or cannot be determined. This is appropriate when the physician's documentation clearly states "poisoning by unspecified agent" or "toxic reaction, agent unknown" with a focus on integumentary or mucosal involvement.

• Ensure documentation explicitly states the agent is "unspecified" or "unknown."
• Do not use if a specific toxic agent is identified; instead, code to the specific substance and manifestation.
• Consider an external cause code (E-code) if the intent (accidental, intentional) and circumstances are known, even if the agent is unspecified.