Fast Acting Allergy Medicine. The best allergy medicine treats inflammation without affecting your adrenal system and target allergies with minimal side effects. Zyrtec, on the other hand, is fast acting. People who take it may feel relief in as little as one hour. Antihistamines like Zyrtec and Claritin are designed to calm the histamine reaction your body has when it’s exposed to an allergen.
Chlor-Trimeton (chlorpheneramine)Chlorpheneramine is the generic for Chlor-Trimeton. It is very similar in most ways to diphenhydramine (number 3). It may work better for some individuals. So if you are looking for a fast-acting medicine that might make you a little sleepy.
BENADRYL® Allergy Relief is the fastest-acting allergy relief capsule, is the only brand to contain acrivastine a unique active ingredient. Most commonly used antihistamine for allergic reaction with slightly faster onset of action then Zyrtec, but most likely to cause drowsiness. Can be dosed every 4-6 hours. Allegra – Least sedating (vs Zyrtec and Claritin), but slightly less effective and shorting acting. Approved for kids 12 yrs.