Allergic contact dermatitis and Covid-19

Just a moment ago you were delighted to have got hold of one of the last bottles of hygienic hand disinfection, but today your skin itches and burns? And your hands are covered with the traces of your endless scratching?

WHEN CONTACT DERMATITIS AFFECTS HAND AND FOREARM

You are not alone in this. Hand contact dermatitis is on the rise worldwide as a result of the overuse of alcohol-based hand sanitizers following the outbreak of the Covid-19 pandemic. When allergic contact dermatitis affects the hand and forearm, it often manifests itself in endless itching and burning, as described at the beginning of this article.

ALLERGIC CONTACT DERMATITIS ON THE RISE

A study just published states that about 75% of medical personnel dealing with Covid-19 patients in China suffer from contact eczema on the hand as a result of hygienic hand disinfection. And in a patient survey in India, about 60% of respondents reported having developed irritant or allergic contact dermatitis on the hand as a result of hygienic hand disinfection due to Covid-19.

These results correspond to my personal observations in my professional environment and in my family: Immediately after the beginning of the corona crisis, my husband developed very itchy complaints on his hands, which have subsided meanwhile. And for a few days now, my daughter has been complaining about the excruciating itching caused by allergic contact dermatitis on her hand.

WHAT IS ALLERGIC CONTACT DERMATITIS?

Contact dermatitis is an inflammation of the skin caused by contact with a certain substance. The main symptom, a rash that is usually very itchy, remains limited to the area of contact and usually has clearly defined edges. Although a distinction is made in principle between toxic-irritant and allergic contact dermatitis, it is often not possible in practice to clearly distinguish between the two forms, given very similar clinical symptoms in patients with subjectively sensitive skin.

WHAT ARE THE SYMPTOMS?

The typical symptoms that characterize both forms of contact dermatitis are itching, burning/stinging of the skin or pain when applying creams and other externals. Patients typically also describe a feeling of tension, which can also affect larger areas of skin. When contact dermatitis affects the hand and forearms as a result of hygienic hand disinfection, the inflamed skin areas typically extend from the fingers and especially the knuckles up the back of the hand and into the forearm. Strong symptoms frequently also form on the sensitive inner side of the forearm. Allergic contact dermatitis can develop erythema in areas or patches, leading to dry, rough and scaly skin. In some patients, wheals and papules have also been observed.

How does allergic contact dermatitis develop?

Allergic contact dermatitis is an immunologically mediated reaction. It does not occur immediately, but only after a certain sensitization phase during which the skin is exposed to the antigen. In practice, the contact with a certain ingredient of a care or cleaning product is initially tolerated without any problems. After a certain time, often several days but also weeks and even months, sensitization occurs and the typical symptoms appear. Therefore, it may well be that you were able to carry out hygienic hand disinfection for a few days without any issues and without your skin initially showing any negative reactions. But if the itching, scaling and tightness suddenly set in, then you almost certainly caught allergic contact dermatitis.

What substances cause allergic contact dermatitis?

The list of antigens that can cause allergic contact dermatitis is long. In a large-scale study, more than 600 ingredients from cosmetics, cleaning products, bath additives and even toothpastes were suspected of causing allergic reactions. In about 10% of the cases, these were fragrances, which has since led to their restrictive use in “anti-allergenic” or “fragrance-free” products.

However, it would be wrong to look for the cause of all evil only in “chemistry”. Numerous herbal ingredients such as camomile, calendula, arnica or sandalwood can also cause allergic reactions in patients with sensitive skin. This is especially bitter for patients who consciously rely on botanical substances because they perceive them as “natural” and thus less problematic than “chemicals”. Incidentally, the same applies to natural oils that are often found in cosmetics, cleaning products and bath additives, such as jojoba oil, tea tree oil or lavender oil.

TOXIC CONTACT DERMATITIS

Toxic contact dermatitis does not require an immunological cause and, in particular, a longer sensitization phase. The inflammatory reaction of the skin usually occurs immediately, typically at the first contact with the irritant. In some manifestations, it may also require repeated contact before inflammatory symptoms appear.

Toxic contact dermatitis is considered the most common form of contact dermatitis. It is estimated that it underlies the inflammatory reactions of the skin in 80% of cases. In practice, we typically speak of “sensitive skin” when people react with inflammatory symptoms to certain active ingredients in cosmetics or chemicals. Examples of cosmetics are hydroxy acids, lactic acid, glycolic acid or retinoids. Regarding chemicals, the list of irritants includes calcium thioglycolate, propylene glycol, benzoic acid or ethanol in care and cleaning products. Even mild soaps and detergents can irritate some people’s skin. The list of substances with potentially irritating effects is long and also includes formaldehyde, urea, ammonium derivatives, perubalsam, cinnamic acid derivatives and certain surfactants such as sodium lauryl sulphate, which is found in many hair shampoos.

ALLERGIC CONTACT DERMATITIS AND WEATHER CONDITIONS

Allergic contact dermatitis (as well as toxic contact dermatitis) can be favoured by climatic influences. Cold, dry air contributes to its formation and aggravation, leading to a more frequent occurrence in winter. Of course, the cold, dry winter air outside or the dry, warm air in heated rooms puts more strain on the skin surface and damages the protective skin barrier. Appropriate care (creams with a high fat content) can prevent this.

WHAT TO DO ABOUT ALLERGIC CONTACT DERMATITIS?

The obvious treatment approach against irritant or allergic contact dermatitis is, of course, to avoid contact with the triggering antigen or at least to reduce it to a minimum. In dermatological everyday life, however, this is easier said than done because patients often do not know which of their many creams, cosmetics, or bath additives could be the cause of the problem. Accordingly, extensive tests are necessary (mostly in the form of patch tests) to first find it.

In our present case of contact dermatitis on the hand, as described above due to frequent hygienic hand disinfection, the culprit is quickly identified. It is one of the alcohols used in common products, mostly ethanol or isopropyl alcohol, typically both together. In different compositions, they form up to 98% of the ingredients, usually supplemented by a little glycerine, which is supposed to have a refatting effect and thus increase the skin-friendliness of these products.

So, the solution is to disinfect your hands less frequently or to do without it altogether. If you are not in the medical sector, this should not be an issue for you. After all, alcohol-based hand disinfection is not needed to destroy the Coronavirus. SARS COV2, as the coronavirus is officially called, is a so-called “enveloped virus” and as such relatively susceptible to external influences. Even mild soap will take care of it without any problems.

As soon as the allergenic substance no longer affects the skin, redness typically disappears within a few days. In the case of scaly skin, it may take a few weeks. In severe cases, there are also medicinal creams and ointments that provide relief from itching. For particularly severe allergic contact dermatitis, over-the-counter hydrocortisone or prescription corticosteroid creams can help, and you may also need to take antihistamines.

In all cases, your doctor will advise you on the best therapy for you. However, it is important to point out once again that allergic contact dermatitis can only be avoided in the long term if the irritation caused by the problem substance (here: the hygienic hand disinfectant) is stopped.

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Eva Maria Strobl, MD
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