Pet Medication 101: Claritin

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Pet Medication 101: Claritin

It’s important to understand a medication’s uses and side effects before giving it to your pet. This medication info sheet is meant to give you a good understanding of what Claritin (loratadine) is used for, how it works, and potential side effects in cats and dogs. Always consult a veterinarian before giving your pet any medication.

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1. Drug Name:


2. Common Names or Brand Names:

Claritin, Alavert

3. How Dispensed:


4. Forms:

10mg tablets, 5mg and 10mg disintegrating tablets, 5mg chewable tablets, 5mg/5mL syrup

5. Drug Type/Class:

antihistamine, piperidine class

6. Uses for Cats and/or Dogs:

vaccine reactions, itchy skin, blood transfusion reactions, bee stings, insect bites, snake bites, mast cell tumor inflammation

7. How it Works:

Loratadine blocks H1 cellular receptors and prevents their activation by histamine. Histamine is an inflammatory biochemical that causes skin redness, tissue swelling, and itching - many of the symptoms that we associate with an allergic reaction. Histamine is released from mast cells and attaches to other cells that have histamine receptors on their surfaces.

There are more types of histamine receptors than just H1 receptors, and histamine is not always the primary mediator of inflammation in pets. This means that antihistamine therapy is not always as reliable in dogs and cats as it is in people.

Loratadine does not cross the blood-brain barrier, and therefore does not cause drowsiness like traditional antihistamines.

8. Side Effects and/or Signs of Overdose:

At higher doses, human patients complain of headaches, drowsiness, and dry mouth. In dogs, vomiting, lethargy, urine retention, and diarrhea have been reported.

Signs of overdose include rapid heart rate, hyperactivity, or depression, depending on how much was ingested.

9. Drug Interactions:

Ketoconazole (an antifungal) and erythromycin (an antibiotic) increase loratadine levels with concurrent use. Do not use these medications together.

10. Cautionary Statements:

  • Never give your dog Claritin without the approval of your veterinarian.
  • Claritin has been known to decrease tear production in humans, so it should be used with caution in dogs with keratoconjunctivitis sicca (dry eye).
  • Do not give your dog Claritin-D because it contains pseudoephedrine, which is highly toxic to dogs.
  • Claritin has not been evaluated for safety during pregnancy or lactation and should not be used in either situation.
  • Use with caution in pets with liver or kidney disease.
  • Claritin syrup is preserved in propylene glycol and should not be used in cats.
  • Disintegrating tablets may contain xylitol, a sweetener that is toxic to dogs.

Read more:

Medication Info Sheet: Zyrtec

Ditch the Itch: Skin Allergies in Dogs

Vaccine Reactions in Dogs and Cats

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