Urticaria due to antihistamines.

H1-antihistamines are probably the most frequently used drugs in allergic diseases, with widely established efficacy, tolerance, and safety. We report a patient with urticaria due to ingestion of ebastine and fexofenadine. Skin prick tests, patch tests, and basophil activation tests with the implicated drugs and antihistamines from other families were negative. The oral challenges with the implicated antihistamines and other antihistamines tested were positive, but the patient tolerated an oral challenge with cetirizine. We present a patient with urticaria induced by different antihistamines in whom the diagnosis was established by oral challenge. The mechanism of sensitization remains unclear.

Potential hypersensitivity due to the food or food additive content of medicinal products in Spain.

The Drug Allergy Committee of the Spanish Society of Allergology and Clinical Immunology reviewed the allergenic potential of several substances of food origin that are found in the composition of some drugs. Despite recent legislation on labeling, many labels do not clearly state whether the drug contains raw material (active ingredients, excipient, or other manufacturing intermediate) with an origin in any of the substances in the list of the 14 groups of food allergens that are subject to mandatory declaration. The objective of legislation is that the drug package, the Summary of Product Characteristics, and the patient information leaflet clearly state the food content in order to improve the safety of allergic patients. Therefore, any food or allergen derivative that must be declared should be clearly stated on the drug label. Of all the evaluated products, egg and milk derivatives are the most frequently discussed in literature reviews. The natural or synthetic origin of potentially allergenic substances such as lysozyme, casein, lactose, albumin, phosphatide, and aromatic essences should be clearly stated. Providing this information has 2 clear advantages. First, allergic reactions to drugs in patients with food allergy could be avoided (if the substances have a natural origin). Second, prescription would improve by not restricting drugs containing synthetic substances (which do not usually induce allergic reactions).

Systemic dermatitis due to tetrazepam.

Cutaneous adverse reactions to benzodiazepines seem to be rare. We report a 61-year-old man with adverse reactions after ingestion of metamizole, diclofenac, and tetrazepam. Skin prick tests with metamizole, diclofenac, and tetrazepam were negative. Patch tests with metamizole, diclofenac, and tetrazepam (all at 5% in aqueous solution) were performed, and were positive for tetrazepam. Oral challenge was performed with metamizole, acetylsalicylic acid, diclofenac, and tetrazepam with a positive result for diclofenac and tetrazepam. The patient tolerated other benzodiazepines. We present a patient who can tolerate diazepam but who had a type IV hypersensitivity reaction to tetrazepam confirmed by patch testing and oral challenge. The patient also presented an immediate hypersensitivity reaction after taking diclofenac.

Fixed exanthema due to paracetamol.

Fixed exanthema represents 10% of the adverse reactions to medications. Up to 80% of the cases are caused by drugs. The lesions are frequently located on the genitals, perianal region, limbs and oral mucosa, in descending order of frequency. We describe the case of a 36-year-old man who developed fixed exanthema following administration of paracetamol.

Fixed eruption caused by ciprofloxacin without cross-sensitivity to norfloxacin.

We report the case of a female patient who presented fixed exanthema following administration of ciprofloxacin. To our knowledge, only one case of fixed exanthema in response to this agent has appeared in the literature, and it was associated with cross-sensitivity to norfloxacin.

Fixed drug eruption due to ibuprofen with patch test positive on the residual lesion

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