Zyrtec vs. Allegra

See how Zyrtec and Allegra compare on approved uses, dosing, side effects, and cost.

Key Takeaways

  • Zyrtec and Allegra are both second-generation antihistamines approved for allergic rhinitis and chronic hives, taken once daily by most adults.

  • Zyrtec causes more drowsiness than Allegra, with somnolence reported in up to 14% of users compared to Allegra's non-sedating profile.

  • Allegra offers more dosing flexibility with once- or twice-daily options, while Zyrtec sticks to a single once-daily dose across all strengths.

Zyrtec vs. Allegra Drug Summary

Zyrtec

Zyrtec (cetirizine) is a second-generation antihistamine used to relieve seasonal and year-round allergy symptoms and chronic hives. It works by blocking histamine receptors and is taken once daily as a tablet, chewable, capsule, or oral solution. It is available over the counter and as a generic.

Allegra

Allegra (fexofenadine) is a second-generation antihistamine used to relieve seasonal allergy symptoms and chronic hives. It is taken once or twice daily depending on the dose, and comes as a tablet, orally disintegrating tablet, or oral suspension. It is available over the counter and as a generic.

Zyrtec vs. Allegra Side Effects

Zyrtec

Most common
somnolence (up to 14%)
fatigue (up to 6%)
dry mouth (up to 5%)
dizziness (up to 2%)

Allegra

Most common
dizziness (2% or more)
headache (2% or more)
back pain (2% or more)
stomach discomfort (2% or more)

Zyrtec vs. Allegra Dosage

Zyrtec

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 2.5 mg once daily At the start
Maximum dose 10 mg once daily If needed
Dose changes 2 increases As tolerated

Allegra

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 30 mg twice daily At the start
Maximum dose 60 mg once daily If needed
Dose changes 3 increases As tolerated

Zyrtec vs. Allegra Indications

Zyrtec

Zyrtec is FDA-approved to relieve symptoms of seasonal and year-round allergic rhinitis, such as sneezing, runny nose, and itchy eyes. It is also approved to treat chronic idiopathic urticaria, an ongoing hives condition with no known cause.

  • Seasonal allergic rhinitis

  • Perennial (year-round) allergic rhinitis

  • Chronic idiopathic urticaria (hives)

Allegra

Allegra is FDA-approved to relieve symptoms of seasonal allergic rhinitis, including sneezing and nasal congestion. It is also approved to treat chronic idiopathic urticaria, the same type of ongoing unexplained hives that Zyrtec treats.

  • Seasonal allergic rhinitis

  • Chronic idiopathic urticaria (hives)

  • Approved for use in children as young as 6 years old

Zyrtec vs. Allegra Pros and Cons

Zyrtec

Zyrtec works quickly and covers both seasonal and year-round allergy triggers, but it carries a higher chance of drowsiness than many other second-generation antihistamines. People with kidney or liver problems may need a lower dose.

Pros

  • Approved for year-round (perennial) allergy symptoms, not just seasonal ones

  • Comes in chewable tablets, syrup, and capsules for easy dosing across ages

  • Single once-daily dose regardless of strength needed

Cons

  • More likely to cause drowsiness than Allegra, up to 14% of users

  • Requires dose reduction in people with kidney or liver impairment

  • Not approved for infants under 6 months old

Allegra

Allegra is one of the least sedating antihistamines available and is metabolized minimally by the liver, which can matter for people on other medications. It offers more dosing flexibility, but that also means more strengths and schedules to keep track of.

Pros

  • Considered non-sedating, with less drowsiness risk than Zyrtec

  • Minimal liver metabolism, a plus for people on liver-cleared medications

  • Once-daily 180 mg option available for adults who want to dose less often

Cons

  • Some formulations require twice-daily dosing, which can be harder to remember

  • The orally disintegrating tablet contains phenylalanine, a concern for phenylketonuria

  • More strengths and schedules across age groups can make dosing confusing

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