The most common side effects of antihistamines in dogs include sedation and drowsiness. This is more commonly noticed with first-generation antihistamines such as diphenhydramine (Benadryl®). Newer generation antihistamines such as cetirizine (Zyrtec® or Reactine®) have less of a sedating effect.
The most common side effect of using Zyrtec for dogs is drowsiness. It's still relatively rare, but it can occur when your dog is just starting to take the medication, or if the dosage is too high. Smaller dog breeds are more susceptible to this side effect.
Antihistamines with the active ingredients of diphenhydramine, chlorpheniramine, cetirizine, clemastine or loratadine are usually safe for most healthy adult dogs. Hydroxyzine is another dog-safe antihistamine and one of the most effective available, but it's only available on prescription.
Unlike Benadryl and other first-generation antihistamines that cause severe drowsiness, Claritin and other second-generation antihistamines rarely make dogs (or people) feel sleepy. Claritin is used to treat symptoms like runny noses and hives in humans, but it is primarily used to address itchy skin in dogs.
Side Effects of Claritin For Dogs
Unlike traditional antihistamines, Claritin doesn't usually cause drowsiness or hyperactivity.
Cetirizine (Zyrtec® or Reactine®) is one of the most commonly used over-the-counter antihistamines recommended by veterinarians. Claritin® can be used but is not typically recommended by veterinarians as some forms of Claritin® contain decongestants such as pseudoephedrine which is very toxic to dogs.
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 antihistamine.
Usually, Claritin will not have any real adverse effect on your dog. However, you should never mix it with any other H1 histamine antagonists, as this may lead to an overdose.
This medication will take effect quickly, in about 1 to 2 hours, and improvement of your pet's signs should follow.
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. Fexofenadine is considered less sedating than other antihistamines.
Benadryl: This mild antihistamine sedative helps keep your pet calm when it is nervous about clipping its nails. Melatonin supplements: Help regulate body rhythm and help calm down your dog. Natural sedation methods: Herbs like California poppy, chamomile, rosemary, or valerian are natural relaxants.
Acepromazine is the most commonly prescribed oral sedative for dogs. It is a member of the phenothiazine class of sedatives and works primarily by blocking dopamine receptors within the brain, thereby depressing certain brain functions.
Melatonin is commonly used as a sleep aid, and is sometimes used to treat certain hair disorders, cognitive dysfunction and separation anxiety in dogs, as well as sleep cycle disorders in dogs and cats.
The euthanasia medication most vets use is pentobarbital, a seizure medication. In large doses, it quickly renders the pet unconscious. It shuts down their heart and brain functions usually within one or two minutes. It is usually given by an IV injection in one of their legs.
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.
The 10 mg pills are okay for dogs between 10 and 50 lbs, though 5-10 lb dogs should only take half (or a 5-mg tablet.) Canines who exceed 50 lbs may take up to two 10 mg tablets if necessary. Dogs under 5 lbs should only take a quarter of a 10 mg tablet or half of a 5 mg pill.
Do not give your dog Claritin-D because it contains pseudoephedrine, which is highly toxic to dogs.
The most common antihistamine for dogs is diphenhydramine (brand name Benadryl). Also found in ProSense Dog Itch & Allergy Solutions Tablets, diphenhydramine is safe in most dogs if given in the recommended dosage of 1 mg of diphenhydramine per pound of body weight given by mouth.
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.
Official answer. According to the American Kennel Club (AKC), you can give the antihistamine Benadryl (diphenhydramine) to your dog, but you should always check with your vet first.
Veterinarians use diphenhydramine, commonly known by the brand name Benadryl, for dogs on a regular basis to treat allergies, travel anxiety, and motion sickness.
Benadryl Tablets
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 2-3 times a day.
Your pet can take antihistamines for life. Certain antihistamines, such as Phenergan can cause drowsiness, otherwise the side- effects are minimal.