Two of the biggies are Zyrtec and Claritin — over-the-counter drugs ... greater overall improvement” in their allergy symptoms compared to people who took a placebo. Zyrtec works by blocking ...

Anti-histamines combined with a decongestant are usually marked with a "D." Claritin-D, Allegra-D, and Zyrtec-D all contain a decongestant called pseudoephedrine, the same active ingredient that ...

“The second generation antihistamines like the ones I mentioned before, Claritin, Zyrtec, and Allegra are intended not to make you sleepy, but everyone’s body is a little bit different.