Dermatitis due to unspecified substance taken internally

This code signifies an inflammatory skin reaction (dermatitis) that is believed to be caused by a substance ingested or absorbed systemically, but the specific causative agent remains unknown or unidentifiable. It represents a systemic allergic or toxic reaction manifesting cutaneously, where the internal trigger is not documented.

Apply this code when a patient presents with dermatitis and the provider explicitly documents a suspected internal cause, but the specific substance responsible for the reaction cannot be determined or is not specified. This is appropriate when the documentation rules out external contact as the primary etiology.

• Do not use if an external contactant is identified; refer to L23.- or L24.- codes.
• Avoid if the specific internal substance is known; instead, use L27.0-L27.8 with the appropriate external cause code (T36-T65).
• Ensure documentation clearly indicates an internal cause and the "unspecified" nature of the substance.