How Long After Taking Claritin Can You Take Zyrtec?

In our latest question and answer, the pharmacist discusses how long you need to wait after Claritin to take Zyrtec.


I took 5mg of Claritin to try it for my hives, and now I wish I had tried Zyrtec in stead. How long do I have to wait before trying the Zyrtec? Thanks

Asked by Gwen On Mar 30, 2018

Answered by
Medical Content Reviewed By PharmacistAnswers Staff

On Apr 01, 2018

A 5 mg dose of Claritin (loratadine) is pretty low. If after an hour or two you don't notice any reduction in your symptoms, it won't hurt you to take the Zyrtec immediately.

Be aware that just Zyrtec alone can make you drowsy and impair your ability to drive or operate machinery; Zyrtec and Claritin together will amplify this effect, so please use caution to avoid a situation where you may injure yourself or others.

Also, no oral antihistamine will rapidly eliminate your symptoms completely. How long the hives reaction lasts depends on what is causing them, whether you are still being exposed to whatever is causing them, and whether you scratch and scrub the area (which irritates the skin even more).

While antihistamines like Claritin and Zyrtec are good options, we have listed some alternatives below that may work faster for acute symptoms.

Treatment For Hives

Claritin Zyrtec Hives

You may have more success with a topical cream or ointment containing hydrocortisone or diphenhydramine, or the anti-itch lotion Sarna. This is because drugs taken orally have more difficulty making it to the outer layers of your skin where the reaction is occurring. Topicals are applied directly to the reaction site, allowing them to act immediately and for a longer duration.

To use a topical preparation, gently wash the area with lukewarm water and soap, preferably unscented soap without extra stuff in it. Use your hands to wash the area...don’t use a cloth or poof, and don’t scrub. Rinse clean and pat (not rub) dry with a clean towel. Your skin doesn’t need to be perfectly dry, and by the time you get the medication out of the package, you should be ready to apply. Apply the recommended amount using your hands, gently rub it in until mostly absorbed, then wash your hands.

If the hives reaction covers a large portion of your body (larger than your hand with your fingers spread as far apart as possible), check with a doctor before using a topical preparation.

If you've had hives before, but don't know what's causing them, it would be a good move to contact an allergist or other physician who can perform a scratch/stamp test. This test exposes you via small scratches in your skin to tiny amounts of a wide variety of substances that humans are often allergic to.

From the level of reaction on your skin, the doctor can tell what you are allergic to, and how severe your reaction is. This will help you to avoid future episodes by reducing your exposure to the offending substance.

About the Pharmacist

Dr. Randall Higgins Pharm.D

Randall is a Doctor of Pharmacy and drug information specialist. His experience as a pharmacist has taken him from retail to specialty infusion and intrathecal pump management. His interests include pain management (particularly non-opioid), substance abuse, addiction and chemical dependency, and drug/non-drug approaches to these areas. He's also extremely interested in finding better ways to provide people with information on complex and often confusing healthcare topics in a way they can understand and relate to.

Recent Questions