Zyrtec vs. Allegra for Allergic Rhinitis and Hives: Important Differences and Potential Risks.

Key takeaways

Cetirizine (Zyrtec) and fexofenadine (Allegra) are both second-generation antihistamines used to relieve allergy symptoms like runny nose and itchy eyes. They have several differences between them. Cetirizine can cause drowsiness, but it's less likely to do so compared to first-generation antihistamines like diphenhydramine (Benadryl). Fexofenadine is even less likely to cause drowsiness than cetirizine. Cetirizine is typically taken once a day, whereas fexofenadine can be taken once or twice a day depending on the formulation. Cetirizine starts working within 20 to 60 minutes, while fexofenadine takes about 2 hours to start working. Both medications come in various forms, but cetirizine offers chewable tablets.

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Cetirizine

(Zyrtec)

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Fexofenadine

(Allegra)

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Summary for Zyrtec

Prescription or over-the-counter

Cetirizine (Zyrtec) is an antihistamine. It's used for relief of allergy symptoms, such as runny nose or watery eyes, in adults and children. Cetirizine (Zyrtec) is also a safe option for people who are pregnant. This medication is available in different formulations, including tablets and liquid solutions. Typically, cetirizine (Zyrtec) is taken by mouth once per day. The most common side effect of cetirizine (Zyrtec) is sleepiness. But it's less likely to make you drowsy compared to some other antihistamines, such as diphenhydramine (Benadryl).

Indications for Zyrtec

Short-term relief of allergy symptoms (sneezing, runny nose, itchy or watery eyes, itching of the nose or throat)
Relief of itchiness due to chronic (long-term) hives in children ages 6 months to under 6 years old - certain liquid solutions only

Pros and Cons for Zyrtec

Pros

First-choice option for relieving allergy symptoms
Taken once per day
Available in several formulations (e.g., pills, chewable tablets, orally disintegrating tablets, liquids)
Safe to take while pregnant

Cons

Can cause you to feel sleepy
Higher risk of side effects in people with liver or kidney problems
Pills can't be used in children younger than 6 years.

Common Side Effects for Zyrtec

People 12 years of age and older:

Sleepiness (14%)
Tiredness (6%)
Dry mouth (5%)

Children age 6 to under 12 years:

Headache (11-14%)
Sore throat (3-6%)
Stomach pain (4-6%)
Cough (3-4%)
Sleepiness (2-4%)

Warnings for Zyrtec

Sleepiness
Accidentally taking too much medication

Summary for Allegra

Over-the-counter

Fexofenadine (Allegra) is an antihistamine. It's used to ease symptoms of allergy and hives in adults and children. Fexofenadine (Allegra) can be found over the counter as a tablet, fast-melting tablet, and liquid. This medication is taken once or twice per day, depending on the formulation. Fexofenadine (Allegra) starts to work in about 2 hours and its effects can last up to 24 hours. Fexofenadine (Allegra) doesn't make you as drowsy compared to some other antihistamines, such as diphenhydramine (Benadryl). Other possible side effects of fexofenadine (Allegra) include headache and dry mouth.

Indications for Allegra

Short-term relief of allergy symptoms (sneezing, runny nose, itchy or watery eyes, itchy nose or throat)
Treatment of hives

Pros and Cons for Allegra

Pros

First-choice option for relieving allergy symptoms
Some products can also be used to relieve itchiness from hives.
Available as 12-hour and 24-hour tablets, as well as a liquid and quick-dissolving tablets for those who have a hard time swallowing pills
All formulations available over the counter

Cons

Liquid form might not be the best choice for people on a low-salt diet because it contains sodium
Once-daily formulations not recommended for children younger than 12 years old
Might have a higher risk of side effects if you have liver or kidney problems
Can cause headache