Systemic allergic dermatitis (systemic contact dermatitis) from pharmaceutical drugs: A review

The literature on systemic allergic dermatitis (SAD; also known as systemic contact dermatitis) is reviewed. Both topical drugs (from absorption through mucosae or skin) and systemic drugs (oral, parenteral, rectal) may be responsible for the disorder. The topical route appears to be rare with 41 culprit topical drugs found to cause SAD in 95 patients. Most reactions are caused by budesonide (especially from inhalation), bufexamac, and dibucaine. SAD from systemic drugs is infrequent with 95 culprit drugs found to cause SAD in 240 patients. The drugs most frequently implicated are mitomycin C, methylprednisolone (salt, ester), and hydrocortisone (salt). The largest group of culprit drugs consisted of corticosteroids (19%), being responsible for >30% of the reactions, of which nearly 40% were not caused by therapeutic drugs, but by drug provocation tests. The most frequent manifestations of SAD from drugs are eczematous eruptions (scattered, widespread, generalized, worsening, reactivation), maculopapular eruptions, symmetrical drug-related intertriginous and flexural exanthema (SDRIFE [baboon syndrome]) and widespread erythema or erythroderma. Therapeutic systemic drugs hardly ever cause reactivation of previously positive patch tests and infrequently of previous allergic contact dermatitis. The pathophysiology of SAD has received very little attention. Explanations for the rarity of SAD are suggested.

Systemic Contact Dermatitis: The Routes of Allergen Entry

Systemic contact dermatitis (SCD) is a generalized reactivation of type IV hypersensitivity skin diseases in individuals with previous sensitization after a contact allergen is administered systemically. Patients with SCD may consider their dermatitis unpredictable and recalcitrant since the causative allergens are difficult to find. If a patient has a pattern of dermatitis suggestive of SCD but fails to improve with conventional treatment, SCD should be taken into consideration. If doctors are not familiar with the presentations of SCD and the possible routes of allergen sensitization and exposure, the diagnosis of SCD may be delayed. In this work, we summarized all of the routes through which allergens can enter the body and cause SCD, including oral intake, local contact (through skin, inhalation, nasal spray and anal application), implants, and other iatrogenic or invasive routes (intravenous, intramuscular, intraarticular, and intravesicular). This will provide a comprehensive reference for the clinicians to identify the culprit of SCD.