Allergy to topical medications

Author: Vanessa Ngan, staff writer, 2012.

What are topical medications?

Topical medications include balms, creams, gels, oils, lotions, patches, ointments and other products that you apply to your skin. They are made up of an active ingredient and base which may contain preservatives and fragrances. Many topical formulations are available over-the-counter and include products such as antibacterial and antifungal preparations, anti-inflammatory and pain-relief preparations, and cleansing and moisturising agents.

What is allergy to topical medications?

An allergy to a topical medication can produce a range of reactions.

Contact urticaria
  • local burning sensation, tingling, itching may occur within minutes to about 1 hour after contact with the skin
  • swelling and redness (wheal and flare) may be seen
  • rash usually resolves by itself within 24 hours of onset
  • difficulty breathing, nausea, vomiting, rash with swelling
  • rarely occurs but can be fatal
Irritant contact dermatitis
  • accounts for 80% of all cases of contact dermatitis
  • can occur in anyone but people with a history of atopic dermatitis are more prone to irritant dermatitis
  • usually begins as patches of itchy, scaly skin or red rash, but can develop into blisters that ooze
  • for strong irritants a reaction may occur within minutes or hours of exposure
  • for weaker irritants it may take days or weeks of continued exposure before symptoms appear
Allergic contact dermatitis
  • reaction only occurs when a person’s immune system is sensitized to the allergen (i.e. person is allergic to a specific ingredient)
  • a rash usually develops more than 12 hours after contact with the allergen and usually peaks about 48 hours after exposure
  • symptoms include redness, swelling, intense itching and hive-like breakouts
  • rash is caused by the interaction of sunlight with an ingredient in the product

Some people may suffer from one or more reactions. In particular, atopic individuals (patients with atopic eczema, asthma and/or rhinitis) are more prone to irritant contact dermatitis, which in turn increases their likelihood of allergic contact dermatitis as their skin barrier function is weakened and more sensitized to the allergen.

What are the allergens in topical medications?

Allergens found in topical medications may be the active drug ingredient or a component of the vehicle or base that carries the drug.

Drug allergens found in topical formulations that have been known to cause allergic skin reactions include:

The groups of allergens found in the base of topical medications that most frequently cause allergy are fragrances and preservatives.

Am I allergic to topical medications?

Allergy to topical medications is diagnosed by performing special allergy tests, i.e. patch tests. Diagnosis may involve testing against the active drug ingredient or a component of the base. See individual contact allergens for patch testing recommendations.

It appears that allergy to topical medications is more common in elderly patients. A study of all patients patch tested at a Sheffield hospital over 9 years confirmed that contact allergy to topical medicaments is more common in those aged more than 70 years compared with the younger age groups.

Some patients with pre-existing skin conditions may be more at risk of developing allergic reactions to topically applied medications.

What is the treatment for allergy to topical medications?

Contact dermatitis should clear rapidly once the offending allergen is removed. In cases where the allergen is not a topical corticosteroid, over-the-counter mild topical steroids, such as hydrocortisone 0.5-2.5%, may be used to help control itching, swelling, and redness. In more severe cases, a prescription steroid cream may be required, as well as antibiotic medication if the skin becomes blistered and infected (impetiginised).

Care needs to be taken when prescribing topical medications to elderly patients with eczema, especially for preparations that contain perfumes, lanolins (wool alcohols), and local anaesthetics as these are the allergens most commonly associated with allergic skin reactions in this group of patients.

Your dermatologist may have further specific advice, particularly if you are highly sensitive to particular allergens.

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