Poisoning by histamine H2-receptor blockers, undet, init

This code signifies a case where a patient has experienced adverse effects from histamine H2-receptor blockers (e.g., cimetidine, ranitidine, famotidine) due to an unknown cause, such as accidental overdose, intentional self-harm, or therapeutic error. The "undetermined" nature indicates that the intent behind the poisoning cannot be definitively established.

Use this code when documenting an initial encounter for a patient presenting with symptoms of H2-receptor blocker toxicity, and the medical record does not clearly specify whether the poisoning was accidental, intentional, or due to therapeutic misadventure. This is appropriate when the provider cannot determine the intent of the poisoning.

• Always assign an additional code for the specific adverse effect or symptom manifested by the patient.
• Ensure the documentation explicitly states that the intent of the poisoning is "undetermined" to support the use of this code.
• This "A" seventh character indicates an initial encounter for treatment of the poisoning.