Antihistamines. Diphenhydramine (Benadryl®), cetirizine (Zyrtec®), and loratadine (Claritin®) are commonly used antihistamines that relieve allergy symptoms or counteract allergic reactions. Antihistamines are usually safe but can make some dogs drowsy and others hyperactive.
According to the Merck Veterinary Manual, the standard dose for Benadryl® is 2–4 milligrams per kilogram of body weight, or 0.9–1.8 milligrams (mg) of Benadryl® per pound. Therefore, a simple and practical dose is 1 mg of Benadryl® per pound of your dog's weight, given two to three times a day.
Your veterinarian can prescribe diphenhydramine capsules for dogs. It's best to avoid using liquid Benadryl if it contains sodium, which can cause other side effects. Also, avoid any form of Benadryl that contains alcohol. Your vet can prescribe diphenhydramine liquid for dogs.
Fexofenadine is available over the counter but should not be administered unless under the supervision and guidance of a veterinarian. This drug is not approved for use in animals by the Food and Drug Administration but it is prescribed legally by veterinarians as an extra-label drug.
OVER-THE-COUNTER ALLERGY DRUGS
You can use over-the-counter antihistamines for your dog's allergies. They can be really quite helpful in some dogs, but they're really unlikely to control an acute or severe flare up.
Telfast®- (active ingredient fexofenadine ) these are available in 60 to 180 mg tabs. But note that while not likely to overdose, the dosage for most dogs is only 5-10 mg / Kg once or twice a day.
The most commonly used antihistamines for dogs include: Diphenhydramine (Benadryl®) Loratadine (Claritin®) Cetirizine (Zyrtec® or Reactine®)
Zyrtec Dosage and Instructions. It is recommended to give your dog 0.5mg per pound of body weight. You can safely give Zyrtec to your dog up to 20 mg per day. It should only be administered orally.
Zyrtec is one of the safer medications you can give to your dog, so as long as you do so correctly and under your vet's guidance, your pet should be good to go. Zyrtec is also a difficult medication for a dog to overdose on. They have an extremely high tolerance for it, so long as they aren't allergic to it.
Here's the recommended Zyrtec dosage for dogs based on their weight: Less than 10 pounds: 2.5 milligrams (half of a 5-milligram pill or a quarter of a 10-milligram pill) 10–50 pounds: One 10-milligram tablet. 50+ pounds: Up to two 10-milligram tablets.
Antihistamines are a type of allergy pill that will sometimes help a dog that has started scratching. As long as your dog has not scratched himself up so much that he is bleeding, an antihistamine will help your dog for the short term until you can visit the vet and find an alternative solution.
If an antihistamine has an additional active ingredient, like pseudoephedrine, your pet may experience severe hyperactivity, hallucinations and even seizures. Because it does not take much of this ingredient to become detrimental, exposures can be life-threatening.
The main active ingredient in piriton is chlorpheniramine which is generally safe for dogs, but other brands may have cetirizine hydrochloride which isn't as safe for your pet.
Cetirizine (Zyrtec®, Reactine®) is an antihistamine used to treat and prevent pruritus (itching) associated with atopic dermatitis, urticaria (hives), and insect bite reactions in cats and dogs.
Zyrtec is an allergy medicine for dogs. It is frequently used to treat skin itching and inflammation associated with atopic dermatitis, a condition caused by a reaction to inhaled allergens. Zyrtec can also be used to treat other allergic reactions, including insect bites and stings and hives.
Antihistamines are commonly used to treat dog allergies. Their histamine-blocking quality tackles airborne allergens and reduces symptoms in your pup. The safest over-the-counter options for your dog include Benadryl, Zyrtec, Claritin, and Allegra.
To help relieve the itching your veterinarian may recommend anti-inflammatories, antihistamines, fatty acid supplements such as MEGADERM® as well as soothing veterinary shampoos such as EPISOOTHE® SIS SHAMPOO.
Telfast 180mg is the highest strength of Telfast available — it contains 180mg of the active ingredient fexofenadine hydrochloride (HCl). Fexofenadine HCl acts quickly (within 1 hour) without causing drowsiness to help relieve the symptoms of hayfever allergies by blocking histamine receptors in the body.
Medication should never be administered without first consulting your veterinarian. Cetirizine is dosed in dogs at 0.5 mg per pound (1 mg/kg) orally once to twice daily.
Pet allergy relief
ZYRTEC® starts working at hour 1 and stays strong day after day, so you can reduce your cat and dog allergy symptoms.
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.