Loratadine (Claritin®, Alavert®) for Dogs and Cats

Loratadine, sold under brand names such as Claritin® and Alavert®, is an over-the-counter antihistamine commonly used in humans to treat allergies. In veterinary medicine, it may also be prescribed to dogs and, to a lesser extent, cats, particularly to help manage itchy skin, seasonal allergies, insect bites, and other mild allergic reactions.

However, because loratadine has not been extensively studied in pets, particularly in cats, its use is considered “off-label” and should always be supervised by a veterinarian.

How Do Antihistamines Work?

When an animal experiences an allergic reaction, the body releases a chemical called histamine. Histamine interacts with receptors on cells, causing symptoms like itchiness, swelling, and inflammation. There are two major types of histamine receptors:

• H1 receptors: Involved in allergic responses affecting skin, eyes, and airways.
• H2 receptors: Influence stomach acid production and heart rate.

Loratadine works by selectively blocking H1 receptors. This helps reduce skin-related allergy symptoms without significantly affecting stomach acid levels or heart rate. Because of its selectivity, loratadine is generally less sedating than older antihistamines like diphenhydramine (Benadryl®).

What Is Loratadine Used for in Pets?

Veterinarians may prescribe loratadine to help manage:

• Itchy skin (pruritus)
• Hives
• Insect bites
• Seasonal allergies
• Mild allergic dermatitis

Loratadine may be especially useful in pets that don’t tolerate more sedating antihistamines. That said, it isn’t effective for all pets or all allergy types, and its benefits vary case by case.

How Much Loratadine Can I Give My Dog?

If you’re wondering “how much loratadine can I give my dog,” it’s critical to consult a veterinarian first. Dosing depends on your dog’s weight, health status, and other medications.

A commonly recommended dosage is 5 to 10 mg once or twice daily, depending on the size of the dog:

• Small dogs (under 15 lbs): 5 mg once daily
• Medium dogs (15–50 lbs): 10 mg once daily
• Large dogs (over 50 lbs): 10 mg twice daily

Another way to calculate the dose is by weight: 0.1 to 0.55 mg per pound (0.25 to 1.1 mg/kg) per day, given once or split into two doses. Never give more than 20 mg in a 24-hour period unless advised by a vet.

Important: Only use plain loratadine tablets. Do not give oral dissolvable tablets or products that contain xylitol, a common sweetener that is toxic to dogs.

Remember: Medication should never be administered without first consulting your veterinarian. This drug has not been well studied in dogs and the oral dispersible tablets may contain xylitol, a known canine toxin. If you’re concerned about costs related to medication, learn how pet insurance may be able to help. Click here to learn more.

Precautions and Side Effects

Though generally safe when used correctly, loratadine may cause:

• Drowsiness or sedation (less common than with other antihistamines)
• Dry mouth
• Vomiting or diarrhea
• Lethargy
• Decreased tear production

Avoid giving loratadine to pets with liver disease, dry eye (keratoconjunctivitis sicca), or known drug allergies. Also, let your vet know if your pet is taking other medications, especially amiodarone, cimetidine, or ketoconazole, which may interact with loratadine.

Loratadine for Cats

Loratadine is not well studied in cats, and no officially approved veterinary formulations exist. Some veterinarians may cautiously prescribe 0.25 mg per pound (0.5 mg/kg) once daily, but always under supervision.

Always Consult Your Vet

While loratadine may help reduce allergy symptoms in dogs, it should never be used without veterinary guidance. If you’re asking “how much loratadine can I give my dog,” remember that even over-the-counter medications can be harmful if dosed incorrectly or combined with the wrong ingredients.

Always read the label carefully, avoid formulations with xylitol, and consult your vet for the safest, most effective treatment plan for your pet.