Many people use antihistamines to treat allergy symptoms. Zyrtec (cetirizine) and Claritin (loratadine) are two popular brands. They contain different compounds but appear to be equally effective. Antihistamines can reduce allergy symptoms, such as watering eyes, itchy skin, hives, and swelling.
Studies have shown equal effectiveness for Zyrtec and Claritin for allergic rhinitis and urticaria. Studies have not compared the effects of Zyrtec and Claritin for conditions such as postnasal drip, but research suggests intranasal antihistamines such as azelastine are more effective.
Cetirizine is considered safe for most dogs. Speak with your vet first to ensure this medication is appropriate for your dog. It is important to only use products that contain cetirizine as the sole active ingredient and avoid human combination products that contain other ingredients that may be toxic to animals.
Common side effects of cetirizine and levocetirizine include fatigue, drowsiness, sore throat, cough, dry mouth, nosebleed, fever, diarrhea, and vomiting.
Antihistamines work by blocking the effects of histamine in your body. Histamine is a substance released by your body when it comes into contact with an allergen. While effective at reducing symptoms, antihistamines can dry out the nasal cavity and lead to nosebleeds.
Common Claritin side effects include headache, dizziness, and digestive side effects such as nausea. Less commonly, some people may experience dry mouth, drowsiness, or fatigue. Claritin side effects are typically mild and can be managed at home.
Some elderly people may have higher risk of side effects because of poor kidney function. The drowsiness and fatigue which may occur in a small percentage of patients may be more of a problem for the elderly because of the increased risk of bone fracture if they fall.
Many people believe they experience a “histamine dump.” This phenomenon usually happens at night when your body releases a sudden surge of histamine. A histamine dump can interrupt your sleep and cause headaches, flushing, itching, anxiety, and a racing heart.
Zyrtec interactions at a glance
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.
Allergy medicines that are safe for your pet include:
Although available over the counter for people, cetirizine should only be given to pets under veterinary supervision. The medication is not FDA-approved for animals, but veterinarians commonly and legally prescribe it as an extra-label drug.
For example, Benadryl® and ZYRTEC® or Claritin and ZYRTEC® should not be taken together. Combining ZYRTEC® with other antihistamine medications can lead to serious complications and, in rare cases, an antihistamine overdose.
headache • sleepiness • fatigue • dry mouth • nervousness • fidgeting • upset stomach • diarrhoea • dizziness The above list includes the more common side effects of your medicine. They are usually mild and short-lived. Other side effects not listed above may occur in some people taking CLARATYNE.
Neither Telfast (fexofenadine) nor Zyrtec (cetirizine) is universally "better," as they are both effective second-generation antihistamines, but they suit different needs: Telfast (fexofenadine) is often preferred for non-drowsy relief, while Zyrtec (cetirizine) might be faster or better for specific symptoms like sneezing and runny nose but is more likely to cause sleepiness in some people. Your best choice depends on your symptoms, how quickly you need relief, and your sensitivity to drowsiness, so consulting a doctor or pharmacist is recommended.
Excess histamine can cause a variety of different symptoms which very often mimic allergic reactions. The most common symptoms are rashes (e.g. hives), itching, flushing, irritable bowel syndrome (IBS), indigestion, breathlessness, palpitations, migraines, dizziness, anxiety/panic, joint aches and nasal congestion.
Histamine levels are another potent downstream target. Allergic symptoms exacerbate during nighttime and plasma histamine levels exhibit nocturnal peaks. In mastocytosis patients, peak levels of plasma histamine were observed in the early morning with the lowest in the afternoon (19).
Under your skin. Near blood vessels and lymph vessels. In nerves. In your lungs and intestines.
The study found that people had a higher risk for dementia if they took:
Older adults should ideally use second-generation antihistamines (like cetirizine, loratadine, or fexofenadine) as they are less likely to cause drowsiness and cognitive impairment compared to first-generation antihistamines.
Medication side effects
They can also make it harder to focus or think clearly. That's why experts recommend antihistamine medications that don't cause drowsiness. Medications like loratadine (Claritin) and cetirizine (Zyrtec) can provide allergy relief without contributing to brain fog.
Side effects of antihistamines
The chewable Claritin tablet may contain phenylalanine and could be harmful if you have phenylketonuria (PKU). Ask a doctor before using this medicine if you are pregnant or breastfeeding. Do not give this medicine to a child younger than 2 years old without medical advice.