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This information is provided by Provet for educational purposes only.

You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

The veterinary literature contains references to skin lesions caused by drugs, but in practice few clinicians seem to have seen a case.

Veterinary textbooks on dermatology describe a variety of toxic reactions to drugs causing skin lesions that vary from mild erythema or urticaria  to necrolysis. In some cases systemic signs are seen as well. Penicillins, cephalosporins and sulphonamide antibiotics are most frequently implicated but that may simply reflect their wide usage in veterinary practice. 

The initial diagnosis is usually based upon known exposure to the drug prior to the onset of the signs and resolution of the signs when the drug is withdrawn. Confirmation of the diagnosis can only be made if the animal is subsequently provocatively challenged with the drug, but this could be risky if the initial "reaction" was immune-based because the animal could develop a life-threatening anaphylactic reaction following re-exposure.

Drugs Reported to Cause Skin Reactions in Cats and Dogs

Any drug can cause a reaction. Pruritus is a common finding irrespective of the route of administration, and the following specific manifestations of skin disease have also been reported* :

Drug Skin Reaction(s) Reported
Antibiotics in general Angioedema, Urticaria, 
Amitraz Angioedema, Urticaria
Ampicillin Pemphigus
Antisera Angioedema, Urticaria
Aurothioglucose Erythema multiforme, Fixed drug eruption, 
Azathiaprine Alopecia, Secondary infection
Bacterins Angioedema, Urticaria
Barbiturates Angioedema, Urticaria
Bleomycin Ulceration over pressure points. Loss of claws.
Blood transfusion Angioedema, Urticaria
Cephalosporins Angioedema, Urticaria, Erythema multiforme
Chlorambucil Alopecia, Secondary infection
Chloramphenicol Erythema multiforme
Cimetidine Pemphigus
Cyclophosphamide Alopecia, Secondary infection
Cyclosporine Hirsuitism, Lymphoplasmacytoid dermatosis, Papillomatosis
Diethylcarbamazine Erythema multiforme, Fixed drug eruption, Pemphigus
Diphenhydantoin Atrophy, Increased fragility
Doxorubicin Alopecia, Flushing, Pruritus, Secondary infection
Etoposide Angioedema, Urticaria
5-fluorocytosine Fixed drug eruption
Gentamicin Angioedema, Urticaria, Erythema multiforme
Glucocorticoids Post-injection atrophy, Alopecia, Secondary infection
Hydroxyurea Alopecia, Secondary infection
Ivermectin Angioedema, Urticaria
Ketoconazole Epitheliotrophic lymphoma
Levamisole Alopecia (patchy), Angioedema, Erythema multiforme, Exfoliative erythroderma, Pustules, Urticaria, 
Lincomycin Exfoliative erythroderma
Mechlorethamine Alopecia, Secondary infection
Penicillins Angioedema, Urticaria, Erythema Multiforme, Vasculitis
Primidone Lupus erythematosus
Procainamide Pemphigus
Progestagens Post-injection atrophy
Propylthiouracil Angioedema, Urticaria
Radiographic contrast media  Angioedema, Urticaria
Retinoids Mucocutaneous erythema and crusts
Shampoos (insecticidal usually) Superficial suppurative necrolytic dermatitis in Schnauzers (Miniature)
Sulphonamides Alopecia (patchy), Angioedema, Urticaria, Erythema multiforme, Exfoliative erythroderma, Pemphigus, Pustules, Vasculitis
Tetracycline Angioedema, Urticaria, Erythema multiforme
Thiabendazole Pemphigus
Thiacetarsamide Fixed drug eruption, 
L-Thyroxine Erythema multiforme
Triamcinolone Bullous pemphgoid
Vaccinations Angioedema, Lupus erythematosus, Post-vaccination panniculitis (eg rabies), Sarcoma formation (eg post-rabies vaccination in cats) Vasculitis (eg rabies), Urticaria

*Table modified after Scott et al. Small Animal Dermatology 5th Edition (available through Provet's On-line discount Bookshop CLICK HERE)

Provet Feedback Request

In humans cutaneous drug reactions may occur in as many as 3/1000 courses of drug therapy. Are we missing the diagnosis in our veterinary patients ? If you have seen a confirmed case of drug eruption please send Provet the details and we shall collate all reports. If we acquire enough data we shall publish the findings later.

Thank YOU


Updated January 2016