What Is the Difference Between Zyrtec & Claritin?

Zyrtec and Claritin are two commercial products designed to treat the symptoms of allergies, hay fever and hives 4. Both medications belong to a class of substances called antihistamines. While Zyrtec and Claritin share many similarities, users of these products must follow different treatment precautions and may develop different medication side effects 4.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.


The generic name of Zyrtec is cetirizine, according to the U.S. National Library of Medicine’s Medline Plus 12. Like other antihistamines, it achieves its effects by blocking the activity of a substance in your body called histamine, which triggers unpleasant symptoms in the presence of irritating materials called allergens. You may receive Zyrtec in forms that include liquid syrup, tablets and chewable tablets. Typically, you will take one dose of the medication at a similar time each day.


The generic name of Claritin is loratadine, Medline Plus reports 24. It achieves its effects through the same basic mechanisms as Zyrtec. You may receive Claritin in forms that include liquid syrup, tablets and tablets designed to dissolve in your mouth 4. Like Zyrtec, you will typically take Claritin once daily 4. In some cases, you may also receive Claritin in products that also contain a nasal decongestant medication called pseudoephedrine 4.

Before Using Zyrtec

Before using Zyrtec, Drugs.com notes, tell your doctor about any other medications you use that can cause sleepiness, including muscle relaxers, sleeping pills or other allergy medications 34. You should also tell your doctor about any known allergies to cetirizine. Use of Zyrtec can alter your normal reactions or thought processes. You should not drink alcohol while using this product, since it may amplify these Zyrtec-related effects. You should also use caution when driving or performing any other task that requires close attention.

Before Using Claritin

Before taking Claritin, you should tell your doctor about any allergies you may have, including allergies to loratadine or a related medication called desloratadine, Drugs.com reports 34. You should also tell your doctor if you have any form of liver or kidney disease. If you have a child who is age 6 or younger, avoid using Claritin without a doctor’s specific recommendation 4. In some cases, dissolving forms of Claritin may contain an amino acid called phenylalanine, which can aggravate a rare genetic syndrome called phenylketonuria, or PKU 4. If you have PKU, you should tell your doctor before using Claritin, Drugs.com explains 34.

Zyrtec Side Effects

Medline Plus lists common minor side effects of Zyrtec use that include stomach pain, dry mouth, diarrhea, vomiting abnormal tiredness and drowsiness. If you experience persistent or severe forms of these side effects, consult your doctor. More serious potential side effects of Zyrtec use include swallowing difficulties and breathing difficulties. If you experience any degree of these effects, get medical attention immediately.

Claritin Side Effects

Medline Plus reports relatively minor potential side effects of Claritin that include:

  • eye itchiness or redness
  • nervousness
  • sleeping difficulties
  • dry mouth
  • diarrhea
  • nosebleeds
  • sore throat
  • headache 4

More serious potential side effects include breathing or swallowing difficulties, hives, rashes and swelling of your face, arms or legs. Tell your doctor promptly about persistent minor side effects and any degree of major side effects.