Antihistamines for Skin Allergies in Dogs

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Antihistamines help to control itching in approximately 1/4 to 1/3 of dogs with skin allergies, especially if started when skin itch is still mild and if used with Omega-3 Fatty Acids (see below). They are inexpensive, readily available as over-the-counter medications, and generally free of side effects. For more severe itch/inflammation, an examination should be performed to look for primary causes (fleas, mites, other) and secondary infections (bacteria, yeast), and stronger, prescription medications (Apoquel, Cytopoint, possibly prednisone) are likely to be needed to make your four-legged friend more comfortable.
In any individual patient, one antihistamine may be significantly more effective than another. Therefore, you may need to try several until one is found that does help, before determining that they are not effective in your dog. Each antihistamine should be given for a 2-3 week trial before determining that it is not effective.
Please note that some liquid or rapid-dissolving tablet forms of antihistamines may contain the artificial sugar, xylitol, which is highly toxic to dogs. Please read labels carefully and do not use Xylitol-containing preparations (and do not EVER give your dog sugarless gum!). Other artificial sugars, such as sorbitol, are safe.
Cetirizine (Zyrtec) ¼ – ½ mg per pound (one 10mg tab per 30-40 lbs) twice daily.
Loratadine (Claritin): ¼ mg per pound (half of a 10mg tablet per 20 lbs) once daily.
Clemastine (Tavist-1, Antihist-1): 0.02mg per pound (one 1.34mg tablet per 65lb dog) twice daily.
Diphenhydramine (Benadryl): 1mg per pound (one 25mg tablet for a 25lb dog) twice daily. May be sedating – may be beneficial to use an night to aid sleeping.
Hydroxyzine: 1mg per pound (one 25mg tablet for a 25lb dog) twice daily. (Prescription product)
Omega-3, Fish-oil Fatty Acids (“Welactin”), at fairly high doses, can really help reduce skin itch
and inflammation and are healthy for the rest of the body. All Fish-Oil products should be dosed
based on their combined dose of the two main Omega-3 Fatty Acids, EPA and DHA
• Dogs less than 30 lbs: 75mg PER POUND of combined EPA and DHA daily
• Dogs 31-60 lbs: 60mg PER POUND of combined EPA and DHA daily
• Dogs > 60 lbs: 50mg PER POUND of combined EPA and DHA daily.
Please work up to these doses gradually over about 2-weeks to allow your dog’s digestive tract to
adjust. Using a high-potency product will minimize the amount of Fish Oil actually needed – We
recommend “Welactin” due to it’s high-potency and purity.