June 12, 2024

Syzal (brand name) or Levocetirizine dihydrochloride is an antihistamine used to treat allergies, symptoms associated with allergic rhinitis, itching and urticaria. It can be taken in the form of tablet and oral solution. Normally, this medication is indicated for the uncomplicated skin manifestations of chronic idiopathic urticaria as well as symptoms associated with perennial  and seasonal allergic rhinitis.

Pregnant or breastfeeding women should use levocetirizine with caution if the benefits outweigh the risks. For FDA (Food and Drug Administration) animal studies of mice and beagle dogs have shown that the drug can excrete in breast milk. Thus, levocetirizine is contraindicated in children under 6 years old, and of course, in people with renal impairment and allergies to levocetirizine or cetirizine. It should be noted that levocetirizine has side effects. They include, but are not limited to, Fatigue, dry mouth, sneezing, runny nose, itchy watery eyes, pharyngitis, and nasopharyngitis.

When absorbed into the human body, levocetirizine acts as an histamine H1 receptor antagonist. Because of that, histamine can’t activate this receptor which leads to effects such as increased permeability of vascular endothelium, stimulation of cough receptors, absorption of histidine into basophils, stimulation of push reactions in the nervous system and smooth muscle contraction. So, since levocetirizine has a wide therapeutic window and long duration of action, patients are warned to avoid tasks that require complete caution or vigilance. If an allergic reaction should occur, it is highly recommended to stop taking your daily dosage and postpone further use until you seek out the advice of your trusted health care professional.

How to use Levocetirizine DIHYDROCHLORIDE

If you are taking the over-the-counter product to self-treat, read and follow all directions on the product package before taking this medication. If you have any questions, consult your pharmacist. If your doctor has prescribed this medication, take it as directed.

This medication is taken by mouth with or without food, usually once daily in the evening.

If you are using the liquid form of this medication, measure the dose carefully using a special measuring device/spoon. Do not use a household spoon because you may not get the correct dose.

The dosage is based on your age, medical condition, and response to treatment. Do not increase your dose or take this medication more often than directed.

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If your condition does not get better or if it gets worse, or if you think you may have a serious medical problem, get medical help right away.

What Other Drugs Interact With Levocetirizine?

If your doctor has directed you to use this medication for allergy symptoms, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider or pharmacist first.

Levocetirizine has no known severe interactions with other drugs.

Serious interactions of levocetirizine include:

  • isocarboxazid
  • tranylcypromine

Moderate interactions of levocetirizine include:

  • clobazam
  • hyaluronidase
  • lurasidone
  • phenelzine
  • ritonavir

Mild interactions of levocetirizine include:

  • dyphylline
  • theophylline

This information does not contain all possible interactions or adverse effects of levocetirizine in treating hay fever. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your prescription drugs with you, and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns or for more information about this medicine.


This medication contains levocetirizine for allergy relief. Do not take Xyzal Allergy 24HR Tablets, Xyzal Allergy 24HR Oral Solution, or Xyzal if you are allergic to levocetirizine or any ingredients contained in this drug. Drug information states to store at room temperature and keep out of the hands of children.