How are skin allergies treated?

Antihistamines to soothe skin allergies.

The first solution for skin allergies: antihistamines. Often prescribed for allergic rhinitis or seasonal allergies, they can also be useful in relieving skin suffering from contact eczema or urticaria. From a mechanistic point of view, antihistamines work by binding to histamine receptors, thus preventing histamine from attaching itself. As a reminder, histamine is a key chemical mediator in allergic reactions. It is produced by mast cells and basophils when the body detects a foreign substance that it considers a potentially dangerous intruder and triggers a cascade of inflammatory reactions leading to redness, swelling and itching by binding with its receptors.

The effectiveness of Fexofenadine Hydrochloride, a second-generation antihistamine, was tested in a recent study. This involved 255 patients suffering from chronic urticaria. The volunteers were divided into 2 groups: 163 took a daily dose of 180 mg of Fexofenadine Hydrochloride, while 92 received a placebo for four weeks. At the end of the study, a significantly greater reduction in papules and itching was noted in the first group. As for the side effects related to the antihistamine, only headaches were reported.

Note : We are discussing here only about antihistamines H1, as H2 antihistamines are used to alleviate certain gastric disorders.

Corticosteroids to alleviate skin allergies.

Another option in the case of skin allergies: corticosteroids. Well known to those prone to eczema, these medications reduce the release of pro-inflammatory cytokines, which helps to decrease local inflammation. Furthermore, corticosteroids inhibit the transcription factor NF-κB by activating the transcription of the IkB gene, which also contributes to reducing inflammation. However, it is important to note that corticosteroids should not be used long-term as their prolonged use can lead to skin thinning or pigmentation changes.

A clinical study evaluated the effectiveness of the daily application of a 0.1% betamethasone cream, a corticosteroid, in conjunction with a moisturising cream on 22 patients suffering from eczema. After four weeks, 91% of the patients, equating to 20 individuals, saw their eczema flare-ups disappear. However, while corticosteroids are useful for alleviating eczema outbreaks, it is important to note that they should not be used between flare-ups.

Calcineurin inhibitors to soothe skin allergy.

Less well-known, calcineurin inhibitors, such as cyclosporine or tacrolimus, are nonetheless interesting for relieving skin allergies. These immunosuppressants work by blocking the activation of T lymphocytes, a type of white blood cell found in skin allergic reactions. These drugs also inactivate calcineurin, which allows the inhibition of the dephosphorylation of the transcription factor NF-AT and prevents its translocation into the nucleus. This action blocks the release of pro-inflammatory cytokines responsible for redness and itching, such as IL-2. Well tolerated, even in the long term, calcineurin inhibitors are nevertheless not recommended for pregnant or breastfeeding women.

Several researchers have explored the effect of calcineurin inhibitors on eczema. A 12-month study involved 267 children suffering from atopic dermatitis who applied a 0.03% tacrolimus cream or a placebo twice a day. Throughout this treatment, scientists observed that tacrolimus helped to reduce the frequency and intensity of flare-ups, unlike the control. Although they are still not widely used, calcineurin inhibitors thus appear to be promising drugs for soothing skin allergic reactions.

Leukotriene inhibitors to combat skin allergy.

When antihistamines or other previously mentioned treatments do not work, leukotriene inhibitors may be a solution. For your information, leukotrienes are mediators of inflammation produced in response to exposure to allergens and are notably metabolites of arachidonic acid. Leukotriene inhibitors, such as montelukast, are primarily used to combat respiratory allergies like asthma, but they can also be effective in alleviating allergic skin reactions. They work by blocking the leukotriene receptors on inflammatory cells, thus reducing overall inflammation.

Even though the effects of leukotriene inhibitors on skin allergies have been relatively understudied, some scientific research highlights their potential. This is particularly evident in a study conducted with 30 patients divided into two groups, all suffering from chronic urticaria. The volunteers in the first group received 10 mg/day of montelukast and an antihistamine (cetirizine) to take if they felt the need for six weeks. Two weeks after the end of the treatment, they received a placebo for six weeks and the same antihistamine. The patients in the second group had the treatment in reverse order. In both groups, the urticaria activity score decreased more significantly during the montelukast treatment than during the administration of the placebo. The use of antihistamines was also significantly less frequent during the montelukast treatment period and an absence of adverse effects was noted.

Biological therapy to combat skin allergies.

Biotherapy, or biological immunotherapy, offers an advanced approach to treating severe allergies, by directly targeting key mediators of the inflammatory response. This therapy utilises monoclonal antibodies administered subcutaneously, such as omalizumab or mepolizumab. Omalizumab primarily works by neutralising IgE, immunoglobulins responsible for the release of histamine by mast cells and basophils, thus playing a significant role in reducing allergic symptoms. Mepolizumab, on the other hand, targets IL-5, a cytokine crucial in the maturation and activation of eosinophils, which are often involved in persistent allergic inflammation.

Biological therapy is primarily reserved for severe or refractory forms of allergies. Its use is often limited to cases where antihistamines and other first-line treatments have not been sufficient.

Desensitisation to halt skin allergy.

Finally, to alleviate a skin allergy, it is possible to undergo desensitisation. This process aims to gradually expose the body to the specific allergen to retrain the immune system and progressively reduce its sensitivity. In the case of skin allergies, desensitisation is primarily considered for environmental allergens such as dust mites, animal hair, and certain pollens, which can cause hives. It is especially recommended when the skin allergy persists despite conventional treatments and becomes bothersome. Desensitisation can span several years and may temporarily worsen the allergy at the start of the treatment.