What is toxicoderma and how does it differ from other dermatitis?
In contact dermatitis, the cause acts externally, and the rash coincides with the contact area. With toxicerma, the substance spreads through the blood, so the rashes are usually symmetrical and occupy large areas of the body. The mechanism is often immune, less often associated with direct toxic effects or accumulation of the drug. Atopic dermatitis is a distinct chronic disease with a hereditary predisposition that usually begins in childhood and is not caused by one specific substance.
- Maculopapular (measles-like) rash is the most common form
- Urticaria and angioedema
- Fixed erythema - a spot in the same place
- DRESS syndrome - rash with fever and organ damage
- Stevens-Johnson syndrome and toxic epidermal necrolysis
- Acute generalized exanthematous pustulosis
Reasons
Almost any drug can cause a reaction, but some groups are more common. The rash usually appears 4-14 days after starting to take a new drug, and sooner if it is re-prescribed. Severe DRESS syndrome develops later, after 2–8 weeks. Viral infections increase the likelihood of rashes: a classic example is rashes when taking certain antibiotics during infectious mononucleosis. Food products cause toxicerma much less frequently than is commonly believed.
- Antibiotics, especially penicillins and sulfonamides
- Anticonvulsants
- Nonsteroidal anti-inflammatory drugs
- Allopurinol
- Radiocontrast agents
- Food additives and colorings
Symptoms
Mild toxicoderma looks like red spots and nodules that start on the torso and spread to the limbs, accompanied by itching. General health hardly suffers. Pain and burning of the skin, dark spots with a bubble in the center, erosion on the mucous membranes of the mouth, eyes and genitals, high fever, swelling of the face, and enlarged lymph nodes are considered alarming. Such signs may indicate severe reactions in which the clock is ticking.
- Red spots and nodules
- Itching
- Blisters, like hives
- Swelling of the eyelids and lips
- Blisters and erosions in severe forms
- Fever and weakness
Diagnostics
The main diagnostic tool is a detailed list of all medications, supplements and new products for the last 2 months with start dates. The doctor compares the timing, appearance of the rash and the known frequency of reactions to each drug. A complete blood count may show increased eosinophils, and biochemistry may show liver and kidney involvement. If the picture is questionable, a skin biopsy is performed. Provocative tests with a suspected drug are carried out only in specialized conditions, and after severe reactions are prohibited.
- List of medications with dates of administration
- Complete blood count with leukocyte formula
- ALT, AST, creatinine
- Skin biopsy according to indications
- Consultation with an allergist after recovery
Treatment and prevention
The first step is to stop taking the suspected drug, but vital medications are stopped or changed only at the doctor's discretion. In mild cases, antihistamines, emollient creams and local glucocorticosteroids are prescribed. Widespread rashes and severe reactions are treated in a hospital, sometimes in an intensive care unit or burn unit. After recovery, the culprit drug is included in the medical records to avoid re-prescription: a second reaction may be more severe.
- Do not take medications unless prescribed
- Inform each doctor about past reactions
- Keep a record of the name of the drug that caused the rash
- Avoid drugs with similar chemical structures
- Do not treat the rash with folk ointments