When used under veterinary guidance, Zyrtec (cetirizine) is generally well-tolerated by dogs, and side effects are uncommon and typically mild.
Ingesting multiple Zyrtec (cetirizine) pills can cause symptoms like drowsiness, vomiting, or rapid heart rate in dogs. Immediate veterinary consultation is crucial. Treatment may include induced vomiting, activated charcoal, and supportive care such as IV fluids. Monitor for neurological signs or allergic reactions.
Common side effects of cetirizine
Cetirizine (Zyrtec) can cause side effects like drowsiness, vomiting, and bloody stool in dogs, indicating possible gastrointestinal irritation or bleeding. Symptoms include lethargy, vomiting, and abnormal stool. Immediate veterinary consultation is essential.
Zyrtec can also cause additional issues for dogs with kidney problems and liver problems. Although adverse reactions seem to be rare, the most common side effect of Zyrtec is sleepiness. Others may include: Constipation.
Dogs can typically take Zyrtec once every 24 hours, although the vet might recommend two daily doses in certain situations. It's often a short-term treatment until the allergy symptoms subside, but it is also safe to take long-term if the dog needs it.
There are situations where dogs should not take Zyrtec: Dogs with kidney or liver disease: These are the organs most active in metabolizing and excreting medications.
Zyrtec-D®, the combination product containing pseudoephedrine, is not safe for use in dogs or cats. Some liquid formulations of cetirizine may contain propylene glycol, which is toxic to cats. Cetirizine orally disintegrating tablets may contain xylitol, which is toxic to dogs.
Common side effects of cetirizine and levocetirizine include fatigue, drowsiness, sore throat, cough, dry mouth, nosebleed, fever, diarrhea, and vomiting.
This medication will take effect in one to two hours and improvement of your pet's symptoms should follow.
What may interact with this medication?
While it does not specifically target an organ, its effects are most noticeable in the skin, nose, and respiratory tract, where allergy symptoms typically manifest. Additionally, as with many medications, it is metabolized by the liver and excreted by the kidneys, so these organs are involved in processing the drug.
The FDA now requires a warning on Zyrtec (cetirizine) and Xyzal (levocetirizine) about severe itching that can happen after stopping the medication. This side effect is rare, but it becomes more likely with long-term use. Slowly reducing your dose (tapering) instead of stopping it all at once may help prevent itching.
Cetirizine (ZYRTEC): 0.25-mg to 0.5-mg per pound for dogs, 5-mg total for cats. These can be given once daily, preferably in the evening. It is available in 5-mg and 10-mg tablets. Do not use with other nervous system sedatives like phenobarbitol.
Zyrtec has become the new first-line drug for dog allergy, largely because of its convenient dosing schedule. Although individual response to antihistamines does vary greatly, this year our clients are seeing a higher response rate than with Benedryl.
Below, we'll go into more detail about eight Zyrtec side effects and how to manage them.
The elimination half-life of Zyrtec is between 8 to 9 hours. It takes approximately 5.5 x elimination half-life for a medicine to be cleared from your system. For Zyrtec this is 5.5 x 9 hours which is about 2 days.
These medicines can cause constipation by blocking the movement of gut muscles. Examples include oxybutynin (Ditropan) and tolterodine (Detrol) for urinary incontinence and diphenhydramine (Benadryl), fexofenadine (Allegra), loratadine (Claritin), and cetirizine (Zyrtec) for allergies.
Side effects from Zyrtec in dogs are rare, but occasionally some dogs experience:
This human medication is used off-label for dogs.
If your dog reacts to a bug bite or has allergies and itches, your veterinarian may recommend Zyrtec to help make him comfortable. Zyrtec (generic name is cetirizine) is a human antihistamine drug and is used “off label” for dogs, as it is not FDA-approved for dogs.
Here's a list of seven of the best allergy medicines for dogs.
Here are some common human medications that can cause kidney failure in dogs.
EFFECTS OF TOXICITY
Large doses of antihistamines can lead to disruption of intestinal smooth muscle function causing gastrointestinal upsets. They can also suppress the respiratory system and impact on the nervous system, causing sedation or excitement.
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.
You can safely give your pet an over-the-counter anti-histamine to relieve their symptoms. The dosage depends on your pet's unique needs and their weight. So, before stuffing any allergy medication into their mouth, check with your veterinarian.