Yes, Xyzal is an antihistamine. Specifically, it’s a second-generation antihistamine, the same class as Zyrtec and Allegra, designed to relieve allergy symptoms without causing as much drowsiness as older options like Benadryl. Its active ingredient is levocetirizine, and it works by blocking histamine receptors in the body to reduce sneezing, runny nose, itching, and hives.
How Xyzal Works
When your body encounters an allergen like pollen or pet dander, it releases a chemical called histamine. Histamine latches onto receptors on cells throughout your nose, eyes, and skin, triggering the familiar symptoms: itching, swelling, sneezing, and watery eyes. Xyzal blocks those receptors so histamine can’t activate them.
What makes levocetirizine notable is how tightly it grips those receptors. Once it binds, it takes roughly 142 minutes to detach, far longer than many competing molecules. That slow release essentially means the drug keeps blocking histamine steadily over a full 24-hour period, which is why a single daily dose is enough for most people. It starts working about one hour after you take it.
How It Relates to Zyrtec
If Xyzal sounds familiar, that’s because it’s closely related to Zyrtec (cetirizine). Cetirizine is actually a 50/50 mix of two mirror-image molecules. One of those molecules, the R-enantiomer, does most of the allergy-fighting work. That molecule is levocetirizine, which is what Xyzal isolates and delivers on its own. The other half, dextrocetirizine, is about 10 times less potent.
In practical terms, a 5 mg dose of Xyzal delivers roughly the same antihistamine activity as a 10 mg dose of Zyrtec because you’re getting only the active half. Both drugs are cleared primarily through the kidneys (70 to 85 percent excreted in urine), and both cross the blood-brain barrier to a similar degree, which is why their side effect profiles are comparable.
What Xyzal Treats
The FDA has approved Xyzal for three specific conditions:
- Seasonal allergic rhinitis (hay fever) in adults and children 2 years and older
- Perennial allergic rhinitis (year-round allergies to things like dust mites or mold) in adults and children 6 months and older
- Chronic idiopathic urticaria (ongoing hives with no identifiable cause) in adults and children 6 months and older
In clinical trials with children aged 6 to 11, a single 5 mg dose suppressed histamine-triggered skin reactions for at least 24 hours, and patients with chronic hives reported significantly less itching compared to placebo through the end of each dosing interval.
Over-the-Counter vs. Prescription
Xyzal was originally prescription-only when it was approved in 2007. In early 2017, the FDA approved a partial switch to over-the-counter status. The OTC version, sold as Xyzal Allergy 24HR, covers seasonal and perennial allergic rhinitis. The chronic hives indication remained prescription-only, so if you’re using it for persistent urticaria, your doctor may still write a prescription.
Side Effects and Drowsiness
Second-generation antihistamines like Xyzal cause less sedation than first-generation drugs like diphenhydramine (Benadryl), but “less” doesn’t mean “none.” Drowsiness is the most commonly reported side effect, and some people notice fatigue or dry mouth. Taking it in the evening can help, since any drowsiness will overlap with sleep rather than your workday. Other reported side effects include sore throat and mild nasal irritation, though these occur at low rates.
Who Should Be Cautious
Because levocetirizine is cleared almost entirely through the kidneys, reduced kidney function changes how the drug builds up in your body. Adults and children 12 and older with mild to severe kidney impairment need lower doses or less frequent dosing. People with end-stage kidney disease or those on dialysis should not take Xyzal at all. Children under 12 with any degree of kidney impairment are also advised against using it, since appropriate dosing hasn’t been established for that group.
If you have normal kidney function and no known sensitivity to cetirizine or levocetirizine, Xyzal is generally straightforward to use: one tablet daily, with or without food, and you can expect relief within an hour that lasts through the next day.