Given at a therapeutic dose, some antihistamines are safe for our furry friends. However, an overdose of these medications can be dangerous. But don't worry, the ASPCA Animal Poison Control Center (APCC) has all the information you need to keep your pet safe and healthy when it comes to antihistamines.
Toxicity to pets
When accidentally ingested by dogs and cats, antihistamine poisoning can result in clinical signs of severe agitation, lethargy, sedation, aggression, abnormal heart rate, abnormal blood pressure, vomiting, diarrhea, inappetance, seizures, respiratory depression, and even death.
According to the Merck Veterinary Manual, the safe dosage is 2-4 milligrams of medication per kilogram of weight, or 0.9 to 1.8 milligrams per pound. This amount can be administered two to three times daily, depending on your dog's symptoms.
The average dog would get 1/4mg per pound; for example, a 16lb dog would get a single 4 mg tablet twice daily. This is one of the few prescription-only antihistamines used in veterinary medicine. Dosing is very similar to Benedryl at 1mg per pound body weight 2-3 times daily.
Benadryl is safe to give your dog for allergies, anxiety, motion sickness, and vaccine side effects. Though a typical Benadryl pill is 25 mg, you should only give your dog 0.9-1.8 mg per pound of weight.
It may be given with or without food. If your pet acts sick or vomits after receiving the medication, try giving it with a small amount of food. This medication will take effect quickly, in about 1 to 2 hours, and improvement of your pet's signs should follow.
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.
This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.
The D in Zyrtec-D stands for pseudoephedrine and is administered to humans as a decongestant medication. However, it can greatly overstimulate a dog's central nervous system (CNS) as well as their heart. This can lead to high blood pressure, canine seizures, and even death.
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.
Side Effects and/or Signs of Overdose:
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.
Toxic dose.
In general, toxicity occurs after ingestion of 3–5 times the usual daily dose. Children are more sensitive to the toxic effects of antihistamines than are adults. The nonsedating agents are associated with less toxicity.
fexofenadine (Telfast®) – this is a second gen. It is available as 60 mg capsules and 120 or 180 mg tablets. The dose is 5–10 mg/kg once or twice daily (don't use if your dog is on ketoconazole or a macrolide antibiotic)
Cetirizine is dosed in dogs at 0.5 mg per pound (1 mg/kg) orally once to twice daily.
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.
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.
1. Drowsiness: Piriton is an antihistamine, so it can make your dogs drowsy in the same way it does humans. Before giving it to your pup, make sure the dosage is correct.
Official answer. The general dose of Benadryl (diphenhydramine) is 2 to 4 mg/kg up to three times day.
A minimum trial of two weeks is often recommended to determine if Fexofenadine is effective for a pet.
Recommended Claritin Dosage For Dogs
The recommended dose for Claritin is 0.2 milligrams per pound of body weight every 12-24 hours. This is only a general recommendation, and as with all medication, you should consult with your veterinarian and have them give you the appropriate dose for your individual dog.
Benadryl Dose for Dogs
As a general rule of thumb, use 1 milligram per pound of your dog's body weight. For example, a 50-pound dog would be given two 25 milligram tablets. Small dogs under 25 pounds can be given children's liquid Benadryl.
Dosage Of Claritin For Dogs
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.