Loratadine (Claritin) vs. Cetirizine (Zyrtec): 7 Ways They Compare

There are many over-the-counter (OTC) options when it comes to managing allergies. For many people, oral antihistamines are a go-to choice. Loratadine (Claritin, Alavert) and cetirizine (Zyrtec) are two popular examples.

In general, all oral antihistamines work similarly well for managing allergy symptoms, and experts don’t consider one to be the “best” antihistamine. So when comparing loratadine versus cetirizine, you have to consider more than just effectiveness.

Below are seven things to keep in mind when choosing between loratadine and cetirizine.

1. Loratadine and cetirizine work in similar ways

Loratadine and cetirizine are both second-generation antihistamines. They work in similar ways to help relieve and prevent allergy symptoms.

Loratadine and cetirizine both work by blocking the effects of the chemical histamine. Your body releases this chemical when you’re exposed to something you’re allergic to. Histamine causes those pesky allergy symptoms, such as sneezing, runny nose, and itchy eyes.

2. Loratadine and cetirizine have slightly different uses

OTC loratadine and cetirizine are both labeled to help relieve common allergy symptoms, such as runny nose and sneezing. When taken daily, they can also help prevent allergy symptoms. For allergy prevention, it’s recommended to start taking loratadine or cetirizine at least 2 weeks before you expect symptoms to begin.

There’s also an IV form of cetirizine (Quzyttir) that can help treat acute, or sudden, hives. Quzyttir is a prescription-only medication that’s given as an IV infusion in a hospital or clinic setting. There’s no IV form of loratadine available.

Good to know: Both loratadine and cetirizine are first-choice treatments for chronic hives. The two antihistamines work similarly well for this condition. But the OTC versions of these medications are not labeled for this use.

3. Loratadine and cetirizine have slightly different dosages

OTC loratadine and cetirizine come in the same dosage forms:

• Oral tablets

• Oral capsules

• Orally disintegrating tablets (ODTs)

• Chewable tablets

• Oral liquid

EXPERT PICKS: WHAT TO READ NEXT

• Is there a best allergy medicine? Learn about the differences between allergy medications so you can choose the right one for you.

• All about side effects: Claritin (loratadine), Zyrtec (cetirizine), and other antihistamines share some side effects, including headache and drowsiness.

• Comparing antihistamines: Learn how Claritin and Zyrtec compare to Allegra (fexofenadine), another antihistamine.

The typical adult loratadine dosage is 10 mg by mouth once a day. The standard cetirizine dosage for adults under the age of 65 is also 10 mg by mouth once a day.

But if you’re 65 or older, it’s recommended to take a lower dose of cetirizine (5 mg). This is because cetirizine is more likely to cause drowsiness or dizziness compared to loratadine, which we’ll explore further later on. These side effects could raise the risk of falls in older adults. So if you’re 65 or older, you may tolerate loratadine better than cetirizine.

As mentioned, cetirizine is also available as a prescription-only IV infusion used to treat sudden hives. There’s a prescription cetirizine eye drop (Zerviate), as well, which can be helpful if your allergy symptoms mainly affect your eyes.

Good to know: Both loratadine and cetirizine are also available combined with the nasal decongestant pseudoephedrine (Sudafed). Claritin-D and Alavert D are brand names for loratadine / pseudoephedrine. And Zyrtec-D is the brand name for cetirizine / pseudoephedrine.

4. Cetirizine may start working faster than loratadine

You may find that cetirizine starts working a bit faster than loratadine. Most people start experiencing allergy relief about 20 to 60 minutes after taking cetirizine. But loratadine usually takes about 1 to 3 hours to start working.

So if you’re looking for the quickest relief, you may consider trying cetirizine.

5. Cetirizine is more likely to cause drowsiness than loratadine

Both cetirizine and loratadine are labeled as “nondrowsy” antihistamines. That’s because most people can take them without getting sleepy, but drowsiness may still occur with all antihistamines. Cetirizine is the second-generation antihistamine that’s most likely to cause drowsiness.

This difference between loratadine and cetirizine is due to how they affect the brain. Cetirizine passes through the blood-brain barrier (BBB) more easily than loratadine. The BBB is a group of cells that protects your brain by keeping many medications and substances out.

Substances that get past this barrier can cause brain-related side effects, such as drowsiness or dizziness. Because cetirizine passes through the BBB more easily than loratadine, it’s more likely to make you sleepy.

6. Cetirizine may cause itchiness after you stop taking it

Some people experience itching when they stop taking cetirizine. This symptom can be severe for some people. Long-term, daily use of cetirizine raises your risk of experiencing this side effect. But some people may experience withdrawal itching even after taking cetirizine for less than 1 month. So it’s best to use only the lowest effective dose for the shortest amount of time needed.

If you experience new or worsening itching when you stop taking cetirizine, contact a healthcare professional. They may suggest slowly lowering (tapering) your dose over the span of a few weeks. In some cases, they may also recommend certain medications to help reduce the itching while your body adjusts to being without cetirizine.

Loratadine isn’t known to cause this side effect.

7. Loratadine and cetirizine have similar interactions

Loratadine and cetirizine interact with similar substances or medications you may be taking. These include:

• Alcohol

• Other oral antihistamines, such as diphenhydramine (Benadryl, ZzzQuil)

• Nighttime cold medications, such as NyQuil (acetaminophen / dextromethorphan / doxylamine)

• Opioids, such as oxycodone (Roxicodone, OxyContin)

• Sleep medications, such as zolpidem (Ambien)

• Other medications that cause drowsiness, such as muscle relaxers and benzodiazepines

These aren’t the only possible interactions. Share a medication list with your pharmacist or other healthcare professional. They can check to make sure you can safely take loratadine or cetirizine with your other medications.

Many loratadine and cetirizine interactions raise your risk of drowsiness. But since loratadine is less likely to make you sleepy, it may be a safer choice if you need to take other medications that cause this side effect.

Good to know: Ask a healthcare professional before combining loratadine or cetirizine with a non-oral antihistamine. Examples include nasal sprays, such as azelastine (Astepro), and eye drops, such as ketotifen (Zaditor). These combinations haven’t been widely studied for safety.

How to save on loratadine and cetirizine

Loratadine and cetirizine are available OTC as brand-name medications, but you can also find them as lower-cost generics.

GoodRx can help you save over 80% on the average retail price of loratadine. You’ll just need a prescription from a healthcare professional in order to apply these savings. Loratadine's price at certain pharmacies is as low as $5.95 for 30 tablets with a free GoodRx discount.

If your healthcare professional writes you a prescription for cetirizine, GoodRx may be able to help you save on the average retail price. Generic cetirizine's price at certain pharmacies is as low as $2.79 for 30 tablets with a free GoodRx discount.

If your healthcare team has prescribed you Zerviate eye drops, there are also ways to save. Anyone with a valid prescription, regardless of insurance status, can use GoodRx to purchase a 30-day supply of Zerviate at an exclusive cash price of $149. And if you meet eligibility requirements, a manufacturer copay card may help you access Zerviate for as little as $59.

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Written by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Ella Bolin, PharmD Candidate

Ella Bolin is a PharmD candidate at Butler University's College of Pharmacy & Health Sciences. She holds a current position as a CVS pharmacy intern and volunteers with Butler University's Community Outreach Clinic (BUCOP) as a medication therapy consultant for the underserved community of Indianapolis.

Reviewed by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

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