Perianal Allergic Contact Dermatitis from Benzocaine – a Case Report

A large number of contact allergic reactions to benzocaine have been reported since its introduction to the pharmaceutical market as an active ingredient in different over-the-counter anesthetic ointments. Benzocaine is used as a key ingredient in many pharmaceuticals, such as products for oral ulcers, wound and burn preparations, sunburn remedies, hemorrhoidal preparations, oral and gingival products, sore throat sprays/lozenges, callous and wart remedies, creams for treatment of poison ivy dermatitis, tooth ache and denture irritation products. We present a 56-year-old Caucasian male with chronic rash, accompanied by intense itching in the perianal area. The lesions occurred two months earlier and the patient was treated with a wide range of topical antifungals, antibiotics and corticosteroids, with temporary improvement. The skin lesions were consistent with chronic allergic contact dermatitis. The patient denied using any topical preparations other than those prescribed by his dermatologist. Patch testing with the European baseline series was performed. A strongly positive reaction to benzocaine was identified on reading days 2 and 3. Targeted history showed intermittent use of benzocaine anti-hemorrhoidal cream to treat concomitant hemorrhoids. Benzocaine was discontinued and treatment with methylprednisolone aceponate 0.1% was initiated, resulting in significant improvement. No relapse was observed at 3-month follow-up. In conclusion, patients with confirmed benzocaine allergy should pay special attention to product labels and avoid products that contain benzocaine and its related substances. All products labelled as “anaesthetic” or “caine” should be suspected of containing benzocaine or related compounds. Patient education and awareness are critical to avoid further episodes and relapses.