loratadine
Claritin, Alavert
Over-the-counter
10mg tablets, 5mg and 10mg disintegrating tablets, 5mg chewable tablets, 5mg/5mL syrup
antihistamine, piperidine class
vaccine reactions, itchy skin, blood transfusion reactions, bee stings, insect bites, snake bites, mast cell tumor inflammation
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.
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.
Ketoconazole (an antifungal) and erythromycin (an antibiotic) increase loratadine levels with concurrent use. Do not use these medications together.
Ditch the Itch: Skin Allergies in Dogs
Vaccine Reactions in Dogs and Cats
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