21 May 2018

All that stings is not allergy

Allergies Clinical Dermatology

Just because alcohol rubs sting, it doesn’t mean you’re allergic to them or should stop using them, healthcare workers were told at the latest dermatology conference. 

When it comes to allergic contact dermatitis, hand cleansers are the culprit eight times as often as alcohol-based hand rubs. Despite this, workers were often forsaking the hand rubs in favour of cleansers, after misinterpreting the sting on broken skin as allergy. 

“We don’t want people giving up on their hand hygiene because it stings,” explained dermatologist Associate Professor Rosemary Nixon, who stressed its importance in reducing staph infections. 

It was important that clinicians understood the difference between irritant contact dermatitis and allergic dermatitis, the Victorian occupational dermatologist said. 

Speaking ahead of her presentation at the Australasian College of Dermatologists’ (ACD) Annual Scientific Meeting on the Gold Coast this week, Professor Nixon discussed the findings of an analysis of data from almost 700 healthcare workers who attended her Occupational Dermatology Clinic over two decades. 

Four in five were diagnosed with occupational contact dermatitis, and of those, 80% had irritant contact dermatitis and 50% allergic contact dermatitis. 

The irritant dermatitis was largely a result of water and wet work, which was common among healthcare workers. Allergic contact dermatitis was often the result of chemicals and preservatives in rubber gloves, hand cleansers and antiseptics. 

Alcohol-based hand rubs only caused allergic contact dermatitis in 1.6% of cases, compared with the 12.4% caused by commercial cleansers. 

So, if a patient felt stinging immediately after using hand rubs, it was far more likely to be irritant dermatitis. 

On the other hand, there had been an “epidemic” of allergic dermatitis from the use of the methylisothiazolinone, a preservative found in everything from baby wipes and facial wipes, to cleansers, lotions, shampoos and deodorants, Professor Nixon said. 

In recent years, companies had eased off using methylisothiazolinone in high concentrations in their products, but it is still a common allergen among patients, she said. 

While Professor Nixon and her team have been petitioning manufacturers to remove known allergens from their products altogether, in the meantime she advised that the first step was to determine what was causing the rash. 

The best way to do this was to take a history, exposure assessment, clinical examination, patch testing, blood tests, IgE prick testing and other diagnostic skin biopsies such as fungal scrapings. 

For allergic contact dermatitis, the site of rash is especially important. It’s necessary for the diagnosis to have a compatible clinical history of contact dermatitis, possible exposure to allergen, and a positive patch test. 

If these were all relevant to the presenting dermatitis, and there was no history of other forms of dermatitis or of irritant exposure, then it was likely to be contact allergy, she said. 

Nevertheless, diagnosis remains complicated. 

Professor Nixon, a world-leader in occupational contact dermatitis, was only accurate in her clinical diagnosis of a patient’s skin condition in two-thirds of cases. 

This underscored the importance of patch testing in these patients, she said, noting dermatologists were often better placed than allergists to perform it. 

If patch tests were negative and allergy was excluded, then the default diagnosis was often irritant contact dermatitis, or a form of endogenous eczema, she said. 

Occupational skin disease is common among healthcare workers, and something many likely put up with. 

Hands are far and away the most common site of dermatitis, followed by arms and face. Two out of three patients she saw had multiple diagnoses and one in four had needed time off work because of it. 

But prevention is the key. Professor Nixon encouraged healthcare workers to practise skin care and use moisturisers after work. 

If a GP suspects contact dermatitis, be it irritant or allergic, advise the patient to avoid any products that are suspected of exacerbating the condition, and then manage it with appropriate accelerator-free gloves, a less irritating soap, moisturising cream and a topical steroid. 

Those who don’t improve should be referred to a dermatologist.