D3.100 - Assessment of the impact of psychotropic drugs, antihistamines, and corticosteroids on the interpretation of skin tests in allergology

A current observed phenomenon is the increase of the prevalence of allergic diseases,which in return is reflected by a growing demand for allergology appointments. Adequate preparation for allergology consultations is essential in order to prevent unnecessary repeated appointments. Allergy diagnosis depends essentially on clinical history; none-the-less, skintesting (skin prick tests and intradermal reaction) is an essential tool for the identification of responsible allergens. The outcome of skin tests depends on a multitude of factors: test site on the body, age, sex, the testing device used, and the treatments received by the patient atthe time of skin testing. Some treatments such as antidepressants, antipsychotics, anxiolytics and sedatives are susceptible to interfere with skin testing due to a potential inherent antihistaminic effect.

We conducted a retrospective, monocentric study aimed to identify treatments/or combination of treatments susceptible to influence skin reactivity during allergology workups. A total of 400 patients were included in our study (200 patients receivingeither psychotropic medication, corticosteroid, and/or antihistaminic, or a combination of these treatments) and 200 control patients not on these medications.

Antidepressants (N=107) were associated with a significant reduction of the histamine positive control of skin testing (Student t-test t=4.71; p<0.001). More specifically, mirtazapine and mianserin were 2 antidepressants associated with complete inhibition of the positive control or a significant reduction of the latter respectively. Similarly, antipsychotics (N=17) were associated with asignificant inhibition of skin reactivity (Student t-test; t=3.89, p<0.001) with quetiapine associated with complete inhibition of the positive control. Hypnotics (N=16) are likewise associated with a reduction of positive control likely due to association with otherpsychotropic drugs.

Our results demonstrate that anxiolytics/sedatives (N=62), antiepilepticdrugs (N=16), and systemic corticosteroids (N=34) are not likely influencing skin reactivity and can hence be continued until appointments. However, further larger studies are required to include more patients treated essentially with single medication (without combination of different psychotropic drugs) in order to better elucidate the potential antihistaminic effectof these medications.