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.
Key facts. You'll usually take loratadine once a day. Loratadine is classed as a non-drowsy antihistamine, but some people still find it makes them feel slightly sleepy. Children may have a headache and feel tired or nervous after taking loratadine.
The most common side effects of antihistamines in dogs include sedation and drowsiness.
Other safe antihistamines for dogs include Claritin (loratadine) and Zyrtec (cetirizine). They produce less sedation than Benadryl does but could still make your dog drowsy. Warning: Make sure your OTC allergy medicine only contains antihistamines.
Benadryl may be more commonly used but can also produce more drowsiness than Claritin or Zyrtec. How long does it take for Claritin to work on dogs? If your dog is suffering from allergies, your dog should show improvement one to two hours after taking Claritin.
And when buying loratadine, make sure the product you buy only contains loratadine, because some products combine loratadine with a decongestant (such as Claritin-D) which can cause side effects in dogs such as a rapid heart rate and pulse and anxiety in a dog and possibly worsen the allergic condition you are trying ...
You may be wondering whether Claritin or Zyrtec is the best pet allergy medicine—but which antihistamine works best for you depends on the severity of your symptoms. For example, a person with a mild allergy to cats or dogs may do well with Claritin. Another person with more severe allergies may do better with Zyrtec.
Vets generally prescribe Claritin for dogs in a dosage 0.2 milligrams per pound of body weight. This can translate as giving a small dog around 5 milligrams of Claritin every day, or 10 milligrams for a larger dog.
Dry mouth, mild stomach upset, trouble sleeping, dizziness, headache, nervousness, loss of appetite, or thirst may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.
Best in the evening: Allergy meds
Once-daily antihistamines, such as Claritin, reach their peak eight to 12 hours after you take them, so using them at dinnertime or before bed means better control of morning symptoms.
Claritin Dosage for Dogs and Cats
Loratadine is dosed in dogs at 0.1 mg per pound to 0.55 mg per pound of body weight (0.25 to 1.1 mg/kg) once daily or divided twice daily. Another way that loratadine is dosed in dogs is by the total dose.
The human antihistamine Claritin (loratadine) is generally safe for dogs and can provide allergy relief. But you should always consult with your veterinarian before giving your dog any human medications.
feeling sleepy, or drowsy, during the daytime – drowsiness usually wears off 8 hours after a dose.
Antihistamines, mainly used to treat symptoms of hay fever or other allergies, can induce drowsiness by working against a chemical produced by the central nervous system (histamine).
Zyrtec is one of the few antihistamines that do not cause drowsiness for most dogs, though there are some exceptions. If Zyrtec makes your dog sleepy, try giving it to them before bedtime to see if that helps their energy levels during the day.
Clemastine Fumarate. Also recommended as an antihistamine for dogs is clemastine fumarate. It is one of the most effective antihistamines for dogs with itchy skin.
Best treatment: Antihistamines
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.
Some of the best oral antihistamines for dog allergies include Curist Allergy Relief (levocetirizine), fexofenadine (brand Allegra), and cetirizine (brand Zyrtec), which can help reduce your sneezing and itching.
One of the side effects of Benadryl is drowsiness, which helps to calm anxious dogs. The Merck Veterinary Manual states that diphenhydramine may relieve symptoms of mild-to-moderate anxiety in pets associated with travel. It also may help relieve motion sickness.
Additional adverse events reported with the combination of loratadine and pseudoephedrine include abnormal hepatic function, aggressive reaction, anxiety, apathy, confusion, euphoria, paroniria, postural hypotension, syncope, urticaria, vertigo, weight gain.
Fexofenadine, commonly known as Allegra® or Telfast®, is a second generation antihistamine drug that may be used for dogs and cats to control itching and other signs related to allergic conditions.