class="Serp__item__snippet--34vQF">For adults, 50mg Benadryl (two 25 mg tablets) is more effective than taking just one, especially for severe allergies or when you have a mast cell disorder (mastocytosis, MCAS, MCAD). When I need to take Benadryl (on top of the H1 and H2 blockers I already take at...