Levocetirizine: what it is & how it works
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Living with allergies can feel like an ongoing challenge, with symptoms that disrupt sleep, energy, and daily routines. For many, finding the right treatment is key to regaining control. Levocetirizine is a second-generation antihistamine, meaning it has been formulated to cause less drowsiness than other types of ‘first generation’ antihistamines.1 It is commonly sold under the brand name Xyzal® and offers a targeted approach to managing allergies. In this article, we’ll explore what levocetirizine is, how it works, and what to expect when using it.
What is Levocetirizine?
Levocetirizine is a second-generation antihistamine[1] designed to treat allergy symptoms and chronic hives. Its active ingredient, levocetirizine dihydrochloride, works by blocking histamine, a chemical in the body that triggers allergic reactions. Unlike older first-generation antihistamines, levocetirizine is less likely to cause drowsiness, making it a more convenient option for daily use.1
This medication is available in various forms, including a levocetirizine 5 mg tablet and oral solutions.
How is levocetirizine different from cetirizine?
Both levocetirizine (Xyzal®) and cetirizine (Zyrtec) effectively relieve allergy symptoms like sneezing, itchy eyes, and a runny nose. However, there are some differences to consider:
- Composition: Cetirizine contains both levocetirizine (active) and dextrocetirizine (inactive), while levocetirizine is the active enantiomer.
- Dosage: the levocetirizine dosage ranges between 2.5 to 5 mg once daily, whereas cetirizine’s dosage ranges from 5 to 10 mg daily.2
Choosing between the two often depends on individual tolerance, response, and cost. Consulting a healthcare provider can help determine the best fit for your needs.
What is Levocetirizine used for?
Levocetirizine is an antihistamine used to relieve the symptoms associated with several common allergic conditions. It is primarily used to treat:
- Seasonal allergies like hay fever
- Year-round allergies like pet dander
- General allergy symptoms (relief from sneezing, runny nose, and itchy eyes)3
Common symptoms Levocetirizine is used to treat
Levocetirizine is primarily known for its effectiveness in relieving the frustrating symptoms that often accompany allergic reactions, including:
- Sneezing
- Runny nose
- Itchy nose or throat
- Red, itchy, or watery eyes 3
- Hives and itching due to hives (by prescription only)
How Levocetirizine works
Levocetirizine functions as an H1 receptor blocker, reducing histamine activity in the body. Histamine is a natural substance released during allergic reactions, causing symptoms like itching and swelling. By blocking this response, levocetirizine provides relief from most allergy symptoms.1
Xyzal® is known for its fast-acting properties, offering noticeable relief within an hour. Its effects last up to 24 hours, making it a convenient once-daily option for sustained symptom control.4
How fast does Levocetirizine work?
Levocetirizine typically starts to work in as little as 45 minutes after being taken. This quick onset provides noticeable relief from most allergy symptoms. The effects are designed to be long-lasting, providing a full 24 hours of symptom control from a single dose.4
Levocetirizine dosage
The recommended levocetirizine dosage varies by age and condition:
- Adults (12–64 years): 5 mg tablet once daily in the evening. A 2.5 mg dose may be appropriate for less severe symptoms.
- Children (6–11 years): 2.5 tablet mg once daily in the evening.
- Children 2 to <6 years: 2.5 mL liquid once daily in the evening.
- Adults 65+ or those with kidney issues: Not recommended.4
Levocetirizine side effects
As with any medication, levocetirizine can cause side effects. For most people, levocetirizine side effects are mild and resolve on their own as the body adjusts to the treatment.
When to go to a doctor
If symptoms persist despite using levocetirizine or if serious side effects occur, consult a healthcare provider immediately. It’s also advisable to seek guidance if you’re unsure about the medication’s suitability for your condition.5
FAQs about Levocetirizine
After taking levocetirizine, drowsiness may occur. In clinical studies where Xyzal® was administered at night, 6% of users experienced drowsiness. Xyzal® should be taken at night, and users should be careful if driving a motor vehicle or operating machinery.
Yes. Xyzal® is safe to use every day in the evening. Use only as directed and please read the product label for complete dosing instructions and warnings.
Talk to your doctor about using levocetirizine for long-term management of symptoms. If you have been using levocetirizine long term, you should also seek medical advice on how to effectively stop taking this medication.3
As with any medicine, you should ask your doctor or healthcare provider about using other allergy medications with Xyzal®.
Levocetirizine is sold under the brand name Xyzal®. 1
Sources:
- Wikipedia contributors. Levocetirizine. In: Wikipedia, The Free Encyclopedia [Internet]. 2025 [cited 2026 Mar 23].
Available from: https://en.wikipedia.org/wiki/Levocetirizine - BuzzRx. Levocetirizine vs. cetirizine: What’s the difference? BuzzRx [Internet]. 2023 [cited 2026 Mar 23]. Available from: https://www.buzzrx.com/blog/levocetirizine-vs-cetirizine
- National Library of Medicine (US). Levocetirizine. MedlinePlus [Internet]. 2026 Feb 15 [cited 2026 Mar 23]. Available from: https://medlineplus.gov/druginfo/meds/a607056.html
- Xyzal. HCP: 24-hour relief for allergies all night and all day. Xyzal [Internet]. [cited 2026 Mar 23]. Available from: https://www.xyzal.com/en-us/hcp
- Mayo Clinic. Levocetirizine (oral route). Mayo Clinic [Internet]. 2026 Feb 1 [cited 2026 Mar 23]. Available from: https://www.mayoclinic.org/drugs-supplements/levocetirizine-oral-route/description/drg-20071083
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