Toxicoderma

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Toxicoderma

Toxicoderma – rashes on the skin and / or mucous membranes that occur after taking medicinal products (ingestion, parenteral, inhalation). The risk of developing toxicoderma when prescribing drugs is 0.3%. Pathogenesis

    • In most cases, toxicoderma is caused by allergies. The development of sensitization to drugs is accompanied by the formation of AT or sensitized lymphocytes. Upon repeated contact with the allergen, an allergic reaction develops (usually type III or IV), accompanied by skin rashes
    • Non-immunological reactions can be caused by the action of the product (for example, striae when using glucocorticoids, petechial rashes with an overdose of anticoagulants), etc.

Clinical picture

    • General manifestations
    • Appearance 5-12 days after the start of taking the product
    • Damage to both skin and mucous membranes
    • As a rule, a reaction to repeated intake of the product.
    • The most frequent manifestations.
    • Hives.
    • Measles-like (maculopapular) rashes (most often appear after the use of barbiturates, sulfonamides, tetracycline) resemble a measles rash, often with a tendency to merge. Perhaps the appearance of large papules and plaques characteristic of pink lichen.
    • Fixed medical rash (often caused by oral contraceptives, barbiturates, salicylates, tetracyclines, sulfonamides)
    • Isolated, well-demarcated, round dark red lesions
    • Occurs soon after taking the product (usually after 2 hours) and with repeated use of the product, and is localized in the same places. Frequent localization in men – the head of the penis.
    • Lichenoid eruptions (gold products, antimalarial products, tetracycline) are polygonal purple papules that merge into scaly patches.
    • Lupus-like erythematous reactions – the appearance on the face of formations similar to those in SLE.
    • Rash associated with photosensitivity.
    • Purple rashes (thiazides, gold products, sulfonamides, NSAIDs, tetracycline) – rashes in the form of purple or reddish spots of various sizes, which do not disappear with pressure and are traditionally localized on the lower extremities.

Acne-like rashes (oral contraceptives, glucocorticoids, iodine products, hydantoin derivatives, lithium products) are pustular formations, unlike acne, there are no comedones.

    • Eczematous eruptions are characterized by the appearance of vesicles, redness, swelling, peeling and severe itching, and are traditionally located on the flexor surfaces of the upper or lower extremities.
    • The most severe manifestations
    • erythema nodosum
    • Multiform exudative erythema
    • erythroderma
    • Lyell’s syndrome.

Diagnosis

    • Careful collection of anamnesis (primarily allergic) in the majority of cases makes it possible to identify the causative factor of toxicoderma
    • Laboratory researches, as a rule, are uninformative. With toxicoderma of allergic genesis, it is necessary to conduct a complete detailed blood test to exclude the development of immune cytopenias (anemia, agranulocytosis, thrombocytopenia) along with toxicoderma
    • Special Studies
    • Skin testing and radioallergosorbent test for specific IgE-ATs (for example, penicillin, insulin, chymo-papain) in IgE-mediated reactions
    • Skin testing of cell-mediated delayed-type hypersensitivity reactions (eg, to para-aminobenzoic acid, nickel) – patch test.

Differential Diagnosis

    • The maculopapular rash, most commonly observed among other forms of toxicoderma, is difficult to distinguish from viral exanthems. When conducting differential diagnosis, the presence of fever, lymphocytosis and other systemic manifestations of a viral infection are taken into account.
    • The forms of manifestations of toxicoderma and various primary dermatitis are almost the same. In the differential diagnosis, anamnesis helps (the connection of dermatitis with taking drugs).

Drug therapy

    • There is no specific therapy in the majority of cases.
    • For itching – antihistamine products, for example, diphenhydramine (diphenhydramine) 25-50 mg every 6 hours or hydroxyzine (Atarax) 10-25 mg every 6-8 hours
    • Emollients for eczematous reactions
    • Glucocorticoids locally – with limited eczematous or lichenoid reactions.

Course and forecast

    • In mild forms, the rash begins to disappear in a day after the withdrawal of the drug that caused toxicoderma
    • Severe forms of toxicoderma can be fatal. Prevention
    • Exclusion of the intake of products that caused toxicoderma
    • When prescribing products, it is imperative to take into account the possibility of cross-reactions.

Synonyms

    • drug rash
    • Drug-induced dermatitis

ICD. 188.7 Pathological reaction to drugs or medications, unspecified