Compare Allegra vs. Zyrtec

Head-to-head comparisons of medication uses, side effects, ratings, and more.

Allegra
(Fexofenadine)

Zyrtec
(Cetirizine)

Treats allergy symptoms. Allegra (Fexofenadine) relieves allergy symptoms without making you feel drowsy.Treats allergy symptoms. Zyrtec (Cetirizine) is a once-daily allergy relief medication that won't make you feel too sleepy.
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Reviews & ratings
Button Group. All currently active
Button Group. All currently active
5.2727272727272725Allegra
Reviews for Allegra (Fexofenadine)
77%
of people say Allegra (Fexofenadine) is worth it
59%
say it works well
0%
say it's a big hassle
Reviews for Zyrtec (Cetirizine)
76%
1% vs. Allegra (Fexofenadine)
46%
13% vs. Allegra (Fexofenadine)
7%
7% vs. Allegra (Fexofenadine)
Side effects
AllegraZyrtec
  • Vomiting 3%
  • Headache 3%
  • Cough 3%
  • Back pain 2%
  • Ear, nose, or throat infection 2%
  • Diarrhea 1%
  • Fever 1%
  • Runny nose 1%
  • Dizziness 1%
  • Stomach discomfort 1%
More Allegra side effects »

We haven’t found good data for Zyrtec side effects.

FDA side effect reports for Zyrtec »
How it works
AllegraZyrtec
Allegra (Fexofenadine) is an antihistamine. It blocks histamine, a chemical that causes congestion, itching, and other allergic reactions.Zyrtec (Cetirizine) is an antihistamine. It blocks histamine, a chemical that causes congestion, itching, and other allergic reactions. Antihistamines can also make you sleepy, but Zyrtec is a low-drowsiness version.
Type of medication
AllegraZyrtec
Antihistamine
2nd generation
Prescription or OTC
Antihistamine
2nd generation
Prescription or OTC
Available as
AllegraZyrtec
  • Pill
  • Dissolving tablet
  • Liquid
  • Pill
  • Liquid capsule
  • Dissolving tablet
  • Liquid
Used for (click to learn more)
AllegraZyrtec
Risk factors for serious side effects
AllegraZyrtec
  • Taking with alcohol
  • Taking other medicines that make you less alert
  • History of phenylketonuria (PKU)
Detailed Allegra (Fexofenadine) risks & warnings »
    • Age 65 or older
    • Taking with alcohol
    • Taking other medicines that make you less alert
    • Current kidney disease
    • Current liver disease
    Detailed Zyrtec (Cetirizine) risks & warnings »
    Pregnancy category
    AllegraZyrtec
    CFDA pregnancy category (Weigh risks vs. benefits)

    Research studies with animals found harmful effects on unborn babies. It hasn’t been properly studied in humans. The benefits might outweigh the risks even if you’re pregnant. Talk with your doctor.

    See the FDA package insert
    NFDA pregnancy category (Unknown)

    The FDA hasn’t classified this medicine’s effects on unborn babies. Talk with your doctor about this medicine if you’re pregnant or planning on it.

    See the FDA package insert
    Alcohol
    No specific alcohol-related info.No specific alcohol-related info.
    Food
    No specific food-related info.No specific food-related info.
    Kidneys and liver
    • The dose needs to be adjusted for people with kidney problems.
    • People with kidney or liver disease may need to take a lower dose of Zyrtec (Cetirizine) to prevent overdose. Talk with your doctor to be sure you are using the correct dose.
    Sex
    No specific sex-related info.No specific sex-related info.
    Sleep
    • Won't make you feel drowsy like some antihistamine medicines.
    • People age 65 and older have a higher risk of troublesome side effects from taking antihistamine medications like Zyrtec (Cetirizine). Watch out for changes in vision, severe dry mouth, trouble urinating, or constipation. Also, feelings of drowsiness may leave you "unsteady" on your feet. This can make you more likely to fall causing broken bones or other serious injuries. Talk with your doctor before using Zyrtec (Cetirizine) and stop using it if you have side effects.
    Weight
    No specific weight-related info.No specific weight-related info.
    Upsides and benefits
    AllegraZyrtec
    • Relieves allergy symptoms, like sneezing, runny nose, and itching.
    • Approved to be used in kids and adults age 6 months and older.
    • Won't make you feel drowsy like some antihistamine medicines.
    • Available over-the-counter without a prescription.
    • Comes in many forms, such as a tablet, liquid, or quick-dissolving tablet.
    • It's okay to take with most other medications since it has very few interactions.
    • Zyrtec (Cetirizine) works as well as other antihistamines to treat sneezing and runny nose, but causes less sedation.
    • Works well to also treat hives and itchy skin.
    • Zyrtec (Cetirizine) is available over the counter without a prescription.
    • It comes as a tablet, liquid, and quick-dissolving tablet.
    • It can provide quick relief of allergy symptoms for both kids and adults.
    • It's okay to take with most other medications because it has few drug interactions.
    • Most people don't get any side effects from Zyrtec (Cetirizine).
    Downsides and risks
    AllegraZyrtec
    • For some people, the effects Allegra (Fexofenadine) has on allergies will wear off over time.
    • May not work as well as the first-generation antihistamines, like diphenhydramine (Benadryl).
    • The dose needs to be adjusted for people with kidney problems.
    • Although it works fast, its effectiveness wears off for some people over time.
    • Zyrtec (Cetirizine) can be slightly more sedating than Allegra or Claritin.
    • Some people find that other more sedating antihistamines, like Benadryl, are more effective for them than Zyrtec (Cetirizine).
    • If you have daily allergy symptoms, a prescription nasal steroid spray might be better for you long-term.
    Tips from our pharmacists for people taking the medication
    AllegraZyrtec
    • Starts working in 1 to 2 hours depending on what dosage form you're taking.
    • Works best when taken regularly, even before symptoms are expected to appear.
    • Can make you feel dizzy or sleepy, so you can take it at bedtime.
    • Follow age-specific dosing and don't take more than recommended.
    • If symptoms get worse or you need to use it for more than a few weeks, talk with your doctor.
    • Starts working in a few hours. Only take it once a day.
    • Can make you feel sleepy, so take it at bedtime if needed.
    • Avoid some of the side effects by drinking plenty of non-caffeinated liquids.
    • If you need to use it for more than a few weeks, talk with your doctor about trying a nasal steroid instead since it might work better for you long-term.
    • Using an antihistamine eye drop instead can also work better to treat itchy or watery eyes.
    Learn more
    More about AllegraSide effectsReviews & ratingsAlternativesFDA package insert
    More about ZyrtecSide effectsReviews & ratingsAlternativesFDA package insert