Skin Allergies: What to do when antihistamines don't work?

When antihistamines are insufficient, there are additional therapeutic options available to alleviate skin allergies such as urticaria or contact dermatitis.

• Corticosteroids.

  Corticosteroids, such as hydrocortisone or betamethasone, reduce local inflammation by limiting the release of pro-inflammatory cytokines. They also act by inhibiting the NF-κB transcription factor through the activation of the IkB gene transcription, thus helping to reduce inflammation. Often prescribed for eczema, the corticosteroids reduce swelling, redness, and itching. However, these creams or ointments are intended to be applied for short periods. Indeed, their prolonged use may lead to skin thinning or pigmentation changes.

• Calcineurin inhibitors.

  In cases where antihistamines prove ineffective following a skin allergy, it is possible to resort to calcineurin inhibitors, such as cyclosporine or tacrolimus. These immunosuppressive drugs block the activation of T lymphocytes, a type of white blood cell involved in the allergic reaction. Moreover, the inactivation of calcineurin inhibits the dephosphorylation of the transcription factor NF-AT and prevents its translocation into the nucleus, which blocks the release of pro-inflammatory cytokines such as IL-2. While calcineurin inhibitors are generally well-tolerated, even over the long term, they are nonetheless not recommended for pregnant or breastfeeding women.

  A study has examined the benefits of calcineurin inhibitors in cases of eczema. Over a 12-month period, 267 children suffering from atopic dermatitis applied a cream containing 0.03% tacrolimus or a placebo twice a day. Throughout this treatment, researchers observed that tacrolimus helped to reduce the frequency and intensity of flare-ups, unlike the control. Therefore, calcineurin inhibitors appear to be promising substitute medications to antihistamines.

• Leukotriene inhibitors.

  Leukotriene inhibitors may be a solution when antihistamines do not work. To recall, leukotrienes are mediators of inflammation produced in response to exposure to allergens and are notably metabolites of arachidonic acid. Leukotriene inhibitors, like montelukast, are primarily used in respiratory allergies such as asthma, but they can also be effective in relieving allergic skin reactions. They work by blocking the leukotriene receptors on inflammatory cells, thus reducing overall inflammation. However, the use of leukotriene inhibitors in skin allergies remains a complementary option, typically explored when the allergy involves both the skin and respiratory systems.

• The biotherapy.

  Also known as biological immunotherapy, biotherapy can be used to combat severe allergies. This technique uses subcutaneously injected monoclonal antibodies, such as omalizumab or mepolizumab, which specifically target certain molecules involved in the allergic inflammatory response, including IL-2 or the tumor necrosis factor TNF-α. It should be noted that biotherapy is generally not considered as a first-line treatment due to its cost and the need for close medical monitoring.

• Desensitization.

  Finally, desensitization is a process aimed at gradually exposing the body to the offending allergen so that the immune system eventually tolerates it. It is recommended when the allergy becomes debilitating, as can be the case with seasonal allergies to pollen, dust mites, or animal hair. It's important to know that the desensitization process can be quite lengthy and extend over several years. Moreover, allergic reaction-type side effects are common at the beginning of the treatment. However, unlike the other options presented above, desensitization has the advantage of treating the allergy and not just its symptoms.

The use of anti-mite covers, hypoallergenic cleaning products, and minimizing exposure to allergens as much as possible are simple actions that should not be underestimated in the fight against skin allergies.