Antihistamines block sweat and cause you to overheat
The body releases histamines in response to an injury, causing swelling. Although this can be uncomfortable, it is essential to protect the body from infections and injuries. However, when histamine is overly reactive, it can mistake harmless things like plant pollen, animal hair, or certain foods as dangerous, causing an allergic reaction. Antihistamines stop this reaction by blocking histamines from being released. Some antihistamines, namely diphenhydramine (Benadryl), can also prevent you from sweating. Perspiration, especially while exercising, help you cool off, so blocking and preventing sweating can cause you to overheat. Taking different antihistamines like cetirizine (Zyrtec), loratadine (Claritin), or fexofenadine (Allegra) are safer options if you’re working out. Also staying hydrated or working out before you take antihistamines can prevent overheating.