Loratadine, the active ingredients in Claritin, is a safe drug to use in dogs for allergies. Typical dosage is 0.1-.05 mg/pound of body weight. Loratadine can cause side effects and does interact with some other medications and should only be administered under the supervision of a veterinarian. Check with your vet before giving loratadine to your dog, and never give a dog Claritin D because it contains pseudoephedrine.