Claritin, like other antihistamines, begins to work within a few hours of taking the medication. For this reason, taking Claritin only on an as-needed basis can be effective for the treatment of hay fever and hives, although taking Claritin daily may result in better overall control of symptoms. While Claritin is effective, other antihistamines, such as Zyrtec (cetirizine) and Allegra (fexofenadine) work better, faster and last longer than Claritin for the treatment of hay fever and hives.
Claritin is generally well tolerated with a low occurrence of side effects. The most common side effects include headache, sedation, fatigue and dry mouth. Sedation is reported to occur in 8% of people taking Claritin, and 6% of people taking placebo in the same study. The rates of the other common side effects of Claritin occur at about the same rate as they do with placebo, meaning that these are not considered to be significant side effects. Claritin has a pregnancy category 'B' rating, meaning that it is generally considered to be safe for pregnant women.
Learn everything you’ve every wanted to know about antihistamines.
Sources:
Alavert package insert. Pfizer Corporation. Website accessed August 7, 2011.
Day J, et al. J Allergy Clin Immunol. 1998;101:638-645.
Day J, et al. Ann Allergy Asthma Immunol. 2001;87:474-481.
Simons FER, et al. J Allergy Clin Immunol. 1990;86:540-7.
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