Phenolphthalein-induced toxic epidermal necrolysis

OBJECTIVE: To report a case of phenolphthalein-induced toxic epidermal necrolysis (TEN) in a patient maintained on several other medications more commonly known to be associated with TEN. CASE SUMMARY: A 78-year-old white man presented with intractable lower back pain and constipation. On day 1 of admission, the patient exhibited a diffuse urticarial rash over his trunk and extremities. History revealed that the patient had taken a combination phenolphthalein/docusate sodium (Correctol) over-the-counter laxative 1 day prior to admission. He had a similar urticarial rash 1.5 years earlier with this product and was instructed not to use it. A biopsy was performed and evidence from light microscopic analysis of the tissue led to a diagnosis of TEN. Furosemide, spironolactone, allopurinol, and hydroxyurea were considered possible causes of the reaction and were discontinued. Despite this, the lesions worsened in severity. The patient subsequently responded well to intravenous antibiotics, intravenous corticosteroids, and local wound care. Furosemide, spironolactone, hydroxyurea, allopurinol, and docusate were all reintroduced without reactivation of the lesions. DISCUSSION: Phenolphthalein is the active ingredient in several over-the-counter laxative preparations and has only rarely been reported to cause TEN. (It is no longer contained in Correctol.) To our knowledge, this case report represents only the third description of laxative-induced TEN. Although this patient had been exposed to several other medications more commonly associated with TEN, his long-term tolerance of and uneventful rechallenge with these medications exclude them as potential catalysts to this drug reaction. The patient's previous rash and the temporal relation of this event and the ingestion of phenolphthalein, as well as the similarity of this case to other reports, point to phenolphthalein as the cause of TEN in this patient. CONCLUSIONS: TEN is a rare disorder that can be fatal in up to 30% of patients. Clinicians should include phenolphthalein in their list of possible causes of drug-induced TEN. A careful and complete medication history can help avoid unnecessary discontinuation of clinically important medications and inadvertent rechallenge with the causative agent.