Zyrtec starts to work within an hour or so after taking the medication -- making it useful for the as-needed treated of hay fever and hives. Taking it daily, however, may result in better overall control of allergy symptoms. Multiple studies show that Zyrtec is better at treating hay fever and hives when compared to Claritin (loratadine) or Allegra (fexofenadine) -- Zyrtec works faster, is more effective, and lasts longer than these other antihistamines.
Zyrtec has a low incidence of side effects, and is usually well-tolerated. Common side effects include sedation, fatigue, dizziness, sore throat and dry mouth. Sedation is reported to occur in 14% of people taking Zyrtec, and 6% of people taking placebo. Fatigue and dry mouth occurred in approximately 5 to 6% of people taking Zyrtec, and in about 2 to 3% of people taking placebo. Sore throat and dizziness occurred at about the same rates for Zyrtec and placebo, meaning that these side effects aren’t likely caused by Zyrtec.
Zyrtec has a pregnancy category 'B' rating, meaning that it is generally considered to be safe for pregnant women.
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