Phenylephrine vs. Zyrtec

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

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Sudafed Pe


Clears your sinuses. Sudafed Pe (Phenylephrine) is a good medication for relieving stuffy nose. It doesn't work as well as pseudoephedrine (Sudafed), but it has fewer side effects.Treats allergy symptoms. Zyrtec (Cetirizine) is a once-daily allergy relief medication that won't make you feel too sleepy.
How it works
Sudafed Pe (Phenylephrine) is a decongestant. It narrows blood vessels and reduces swelling in your nasal passages to make breathing easier.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
DecongestantPrescription or OTC
2nd generation
Prescription or OTC
Available as
  • Pill
  • Nasal spray
  • Eye drops
  • Suppository
  • Pill
  • Liquid capsule
  • Dissolving tablet
  • Liquid
Used for (click to learn more)
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Reviews & ratings
Button Group. All currently active
Button Group. All currently active
Reviews for Sudafed Pe (Phenylephrine)
of people say Sudafed Pe (Phenylephrine) is worth it
say it works well
say it's a big hassle
Reviews for Zyrtec (Cetirizine)
+32% vs. Sudafed Pe (Phenylephrine)
+23% vs. Sudafed Pe (Phenylephrine)
+3% vs. Sudafed Pe (Phenylephrine)
Side effects

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

FDA side effect reports for Phenylephrine »

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

FDA side effect reports for Zyrtec »
Risk factors for serious side effects
  • History of high blood pressure
  • Taking MAO inhibitors
  • History of heart problems
  • Age 65 years or older
  • Women of childbearing age
Detailed Sudafed Pe (Phenylephrine) 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
    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
    No specific alcohol-related info.No specific alcohol-related info.
    No specific food-related info.No specific food-related info.
    Kidneys and liver
    No specific kidneys and liver-related info.
    • 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.
    No specific sex-related info.No specific sex-related info.
    • Shouldn't use it before you want to sleep.
    No specific sleep-related info.
    No specific weight-related info.No specific weight-related info.
    Upsides and benefits
    • Works to clear nasal congestion and helps you breathe better.
    • Helpful in relieving congestion-related headaches.
    • Has fewer side effects than other decongestants like pseudoephedrine.
    • It doesn't raise your blood pressure and heart rate as much, or cause as much trouble falling asleep.
    • Doesn't give you rebound congestion (worse symptoms when you stop taking it) like nasal spray decongestants do.
    • 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
    • Phenylephrine doesn't last as long as other decongestants like pseudoephedrine (Sudafed).
    • You shouldn't use it if you have high blood pressure.
    • Can make your heart race or make you feel anxious and restless.
    • Shouldn't use it before you want to sleep.
    • Not as effective after using it for 4 days in a row.
    • 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
    • Starts working in 30 minutes.
    • Phenylephrine can make you restless, so don't take it too close to bedtime.
    • It's in other cold and flu combination medicines. Read labels closely so you don't accidentally double up and take too much of it in a day.
    • Follow age-specific dosing instructions on how much to take.
    • Let your doctor know if your symptoms don't improve in a few days.
    • 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 PhenylephrineSide effectsReviews & ratingsAlternativesFDA package insert
    More about ZyrtecSide effectsReviews & ratingsAlternativesFDA package insert