Toxidermia: identifying and treating this drug allergy

Drug eruption refers to adverse effects and complications following the administration of drugs by dermal application, ingestion, inhalation or injection. The vast majority of toxidermias are said to be benign: they induce maculopapuleu exanthema, urticaria, pruritus, transient photosensitivity, etc. Reactions can be acute and unpredictable, sometimes occurring long after taking the drugs.

Severe drug eruption, they involve the vital prognosis of patients: acute generalized exanthematous pustulosis (AGEP), drug hypersensitivity syndrome (DRESS), Stevens-Johnson syndrome (SJS) and Lyell syndrome (toxic epidermal necrolysis). They should not be overlooked.

Please note: commonly used medications induce toxidermia in 1 to 3% of patients However, as indicated previously, more than 90% of drug eruption are considered benign. The frequency of severe forms (serious sequelae, even death) is 2%.

The signs of drug eruption can manifest differently in everyone:

• urticaria,
• itching,
• eczema,
• photosensitivity,
• angioedema and anaphylactic shock,
• alopecia,
• psoriasis,
• acne,
• redness,
• appearance of blisters,
• purpura,
• lichen,
• fever,
• etc

Drug eruption is difficult to identify, due to the wide variety of symptoms. Diagnosis is based on the onset of symptoms coinciding with taking medication. The disappearance of symptoms when the drug is stopped and any recurrences then confirm the hypothesis of drug eruption. Be that as it may, it always manifests itself following the taking of a drug, at the usual doses. Many of them are likely to cause drug eruption:

• antibiotics,
• sulfonamides,
• paracetamol,
• aspirin,
• local anesthetics,
• barbiturates,
• medicines containing iodine,
• quinine,
• gold salts,
• griseofulvin,
• etc

Severe drug eruption can be life-threatening following significant skin failure (epidermal necrosis that would not have been taken care of in time, for example), or following visceral complications.

The most common – and dangerous – complications:

• angioedema and anaphylactic shock,
• pustular drug eruption, characterized by a sudden eruption,
• drug hypersensitivity syndrome,
• Stevens-Johnson syndrome or Lyell syndrome (toxic epidermal necrolysis), two forms of bullous dermatosis,
• etc

Other non-cutaneous symptoms may occur:

• digestive disorders (nausea, vomiting, diarrhea, etc.),
• breathing difficulties,
• asthma,
• a disturbance of the waste elimination function by the kidneys,
• etc

If you or someone close to you shows signs of drug eruption, see a doctor quickly. Also be sure to trace the history of your medication intake, but wait for the opinion of a specialist to suspend your treatments.

The main solution is to stop taking medication, on medical advice. Until the reactogenic substance is evacuated, it is possible to treat the cutaneous symptoms with specific creams to reduce pruritus, or even to take antihistamines to soothe itching (ask your doctor or pharmacist for advice).

Hospitalization may sometimes be necessary in the event of severe drug eruption. Additional examinations will then make it possible to determine which exact molecule induced the toxidermy. And the taking of new drugs will be done in a medical environment to prevent any new form of complications.