A dose-dependent delayed hypersensitivity reaction to acetaminophen after repeated acetaminophen intoxications

Area of Science:

• Clinical Toxicology
• Psychiatry

Background:

• Borderline personality disorder (BPD) can be associated with self-harm behaviors, including intentional drug overdosage.
• Acetaminophen (paracetamol) is a common over-the-counter analgesic frequently used in overdose scenarios.

Observation:

• A 29-year-old woman with BPD presented with nine intentional acetaminophen overdosages over 21 months.
• The patient developed a rash during treatment, initially attributed to intravenous N-acetylcysteine (NAC).
• Subsequent re-exposure to acetaminophen and NAC led to recurrent rash, prompting re-evaluation of the cause.

Findings:

• The anaphylactoid reaction was ultimately ascribed to high-dose acetaminophen exposure rather than NAC.
• Methionine treatment for the suspected NAC reaction also resulted in rash recurrence.
• N-acetylcysteine therapy was successfully reinstituted after considering acetaminophen as the likely allergen.

Implications:

• This case highlights the importance of considering acetaminophen as a potential cause of anaphylactoid reactions in overdose patients.
• Withholding effective N-acetylcysteine therapy due to a presumed reaction can have serious consequences.
• Accurate diagnosis of the allergen is crucial for appropriate management of acetaminophen poisoning and associated complications.