Cetirizine and levocetirizine both belong to the class of medicines known as antihistamines. According to the NHS, antihistamines are commonly used to relieve symptoms of allergies such as hay fever, hives, conjunctivitis, and reactions to insect bites or stings.
Before understanding cetirizine and levocetirizine, it is important to understand about the types of antihistamines in general. Antihistamines are mainly divided into two subtypes: H1 and H2 antihistamines.
These are indicated for allergic rhinitis, conjunctivitis, dermatologic reactions, sinusitis, acute and chronic urticaria, angioedema, atopic dermatitis, adjunct therapy, bronchitis (symptomatic), and motion sickness.
These are indicated for peptic ulcer disease, gastroesophageal reflux disease, gastritis, and Zollinger-Ellison syndrome.
H1 antihistamines include first and second generation, also termed as sedating and non-sedating antihistamines respectively.1
Cetirizine and levocetirizine both belong to second generation antihistamines.
Cetirizine is considered one of the most potent second-generation antihistamines, based on surrogate markers of effectiveness such as suppression of skin reactivity to histamine.
Levocetirizine, a newer antihistamine, is the R-enantiomer of cetirizine. Cetirizine is a racemic mixture, meaning it contains two mirror-image forms, whereas levocetirizine represents the pharmacologically active form. Studies evaluating histamine suppression have shown that 2.5 mg of levocetirizine is comparable to 5 mg of cetirizine, suggesting that most of cetirizine’s antihistaminic activity is attributable to its levocetirizine enantiomer. 2
H1 receptors play a role in mediating allergic reactions, including vasodilation, bronchoconstriction, pruritus, and central nervous system (CNS) wakefulness. H1 antihistamines act by blocking these receptors, thereby reducing allergic symptoms.
Second-generation antihistamines such as cetirizine and levocetirizine primarily act on peripheral H1 receptors. They have longer half-lives, improved tolerability, and cause less sedation compared to first-generation antihistamines. 1
Relief of seasonal and perennial allergic rhinitis
Chronic idiopathic urticaria
Intravenous formulation for acute urticaria 1
Relief of seasonal and perennial allergic rhinitis
Uncomplicated skin manifestations of chronic idiopathic urticaria1
In a discussion on MedBound Hub, Dr. Nischal Agrawal, Pharm D, Krupanidhi College of Pharmacy, Bengaluru, shared insights on the clinical preference for both drugs.
A cost-effective treatment is required
Mild to moderate allergy symptoms are present
Night-time dosing is acceptable
Daytime alertness is important (e.g., students, drivers)
Stronger symptom control is needed
A lower dose with improved efficacy is preferred
Dr. Nischal Agrawal suggested:
"Both levocetirizine and cetirizine are effective in treating allergic conditions. Levocetirizine offers improved potency and reduced sedation, making it clinically useful for patients who require better symptom control with fewer side effects, whereas cetirizine remains a reliable and economical option."
Sanghavi N. Deshpande, Pharm D graduate, added:
"Levocetirizine would definitely be my drug of choice because it provides the required effect with less sedation and does not interfere with day-to-day activities, making it very helpful for working professionals and college-going individuals."
A 2009 study3 comparing the efficacy of cetirizine and levocetirizine in chronic idiopathic urticaria concluded that:
The overall clinical efficacy of both drugs was comparable
Levocetirizine showed a marginal advantage in antipruritic effect, possibly at the cost of increased sedation
Both cetirizine and levocetirizine are second-generation H1 antihistamines
Levocetirizine is the active R-enantiomer of cetirizine
Cetirizine is a more cost-effective option as compared to Levocetirizine
The choice of medication depends on symptom severity, patient lifestyle, and budget
1. Farzam K, Sabir S, O'Rourke MC. Antihistamines. [Updated 2025 Dec 13]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK538188/
2. Tzanetos, Douglas B., John M. Fahrenholz, Theresa Scott, and Kristina Buchholz. 2011. “Comparison of the Sedating Effects of Levocetirizine and Cetirizine: A Randomized, Double-Blind, Placebo-Controlled Trial.” Annals of Allergy, Asthma & Immunology 107 (6): 517–522. https://doi.org/10.1016/j.anai.2011.08.012.
3. Garg, G., & Thami, G. P. (2007). Comparative efficacy of cetirizine and levocetirizine in chronic idiopathic urticaria. Journal of Dermatological Treatment, 18(1), 23–24. https://doi.org/10.1080/09546630601028745
Disclaimer: This article is for informational purposes only and should not replace professional medical advice. Always consult a healthcare provider before starting or changing any medication.