Cetirizine HCl
Zyrtec
Zyrtec — original cetirizine antihistamine by UCB, the inventor of cetirizine. Fast allergy relief within 1 hour, 24-hour lasting.
💊 Active Ingredient: Cetirizine HCl 10mg
⏱️ Usage: 1 tablet daily, anytime
🍽️ Conditions: Can be taken with or without food
📦 Pack: 10 film-coated tablets/strip
⚡ Highlight: Original brand with 30+ years of clinical data
🌡️ Storage: ≤30°C, protect from light and moisture
Shipping
Discreet shipping within Thailand — packaging does not identify the product. Customers can review shipping and return conditions per our store policy. Contact our team for any questions.
Product Description
Zyrtec is the original brand of Cetirizine HCl 10 mg — a second-generation H1-antihistamine developed and patented by UCB Pharma (Belgium). It selectively blocks peripheral H1 histamine receptors with minimal CNS penetration, delivering potent allergy relief with significantly less sedation than first-generation antihistamines.
- Developed by UCB Pharma, the company that originally discovered and synthesized Cetirizine — providing the most comprehensive safety and efficacy data of any Cetirizine product
- Once-daily dosing with 24-hour duration of action — effective for both seasonal allergic rhinitis (hay fever) and perennial allergic rhinitis (year-round allergies)
- Zyrtec 10 mg is also indicated for chronic idiopathic urticaria (hives) and pruritus associated with atopic dermatitis
- Available as 10-tablet blister strips and 60 ml syrup formulation for those unable to swallow tablets
🏭 Manufactured by UCB Pharma (Belgium) · ATC: R06AE07 · Cetirizine HCl 10 mg
⚠️ Zyrtec is taken once daily (morning or evening), with or without food. Do not exceed 1 tablet per day in adults with normal renal function. Dose adjustment required for renal impairment (CrCl <30 mL/min).
About Zyrtec
What is Zyrtec?
Zyrtec is a 2nd-generation H1-antihistamine containing Cetirizine Hydrochloride 10 mg, developed by UCB Pharma (Belgium) — the original inventors of Cetirizine.
- Blocks peripheral H1 histamine receptors, reducing histamine release that causes runny nose, sneezing, itching, and swelling
- Rapid absorption within 1 hour, 24-hour duration of action — convenient once-daily dosing
- Lower CNS penetration than 1st-generation antihistamines, resulting in significantly less sedation
- Available as 10-tablet blister strips and 60 ml syrup formulation
Zyrtec effectively manages: allergic rhinitis, chronic urticaria, atopic dermatitis pruritus, and allergic conjunctivitis.
How Zyrtec Works
The mechanism of action of Zyrtec (Cetirizine):
- Selective H1 receptor antagonist: Cetirizine binds specifically to H1 receptors on mast cells, basophils, and endothelial cells, competitively blocking histamine binding
- Anti-inflammatory activity: Beyond antihistamine effects, Cetirizine inhibits eosinophil and basophil migration into inflamed tissue
- Peripheral selectivity: Cetirizine molecular structure limits CNS penetration (low lipophilicity), producing minimal sedation compared to 1st-generation antihistamines
- Onset and duration: Effect onset within 1 hour, peak at 1-2 hours, sustained for 24 hours with once-daily dosing
Indications & Uses
Zyrtec is approved for the following indications:
- Allergic Rhinitis — both Seasonal (hay fever) and Perennial (year-round): runny nose, sneezing, nasal congestion, nasal and ocular pruritus
- Chronic Idiopathic Urticaria (CIU) — relieves hives, intense skin itching, and wheals
- Atopic Dermatitis — reduces pruritus that disrupts sleep quality
- Allergic Conjunctivitis — reduces tearing, eye itching, and conjunctival redness
Zyrtec is taken as one 10 mg tablet once daily, at any convenient time, with or without food.
Dosage & How to Take
Dosage and administration for Zyrtec 10 mg:
- Adults and children 12 years and older: 10 mg (1 tablet) once daily at any time, with or without food
- Children 6-11 years: 5 mg (half tablet) once or twice daily based on weight, or 5 mg/5 ml syrup
- Elderly: Standard adult dose; exercise caution with renal impairment
- Renal impairment (CrCl 10-30 mL/min): Reduce dose to 5 mg per day
- Hepatic impairment: No dose adjustment required; Cetirizine is primarily renally excreted
For best results, take Zyrtec at the same time each day to maintain consistent plasma drug levels.
Side Effects & Precautions
Potential side effects of Zyrtec:
- Common (1-10%): Mild drowsiness, dry mouth, headache, fatigue
- Uncommon (<1%): Nausea, abdominal discomfort, palpitations, blurred vision
- Caution for drivers/operators: Although Zyrtec causes less sedation than 1st-generation antihistamines, individual responses vary — assess personal tolerance initially
- Renal impairment: Cetirizine is primarily renally excreted; dose adjustment required for CrCl <30 mL/min
- Alcohol: May potentiate sedative effects — concurrent use is not recommended
Drug Interactions
Drug interactions to be aware of with Cetirizine (Zyrtec):
- CNS Depressants: Sedatives, benzodiazepines, opioids — may potentiate sedative effects
- Alcohol: Enhances sedation — concurrent use is not recommended
- Theophylline (high dose): May slightly reduce Cetirizine clearance; not clinically significant at standard doses
- Ritonavir (HIV antiretroviral): May increase Cetirizine plasma levels; monitor in patients on antiretroviral therapy
- Anticholinergic drugs: Additive anticholinergic effects (dry mouth, urinary retention)
Cetirizine undergoes minimal CYP450 metabolism, resulting in fewer pharmacokinetic drug interactions compared to some other antihistamines.
Storage & Packaging
Storage and packaging guidelines for Zyrtec:
- Temperature: Store below 30 degrees Celsius at room temperature; avoid direct heat and sunlight
- Humidity: Keep in a dry location; do not store in bathrooms or humid areas
- Packaging: Blister pack of 10 tablets per strip — moisture and light-protective barrier
- Expiry date: Check the expiration date printed on packaging before use
- Safety: Keep out of reach of children and pets at all times
The Zyrtec blister pack format provides superior moisture protection compared to loose tablet bottles, maintaining potency throughout the shelf life.
Storage & Packaging
Storage instructions:
- Store at temperatures not exceeding 30°C
- Protect from direct sunlight and moisture
- Keep in the original sealed container
- Store out of reach of children
Packaging:
- Form: Film-coated tablet
- Strength: 10 mg per tablet
- Pack size: 10 tablets per blister strip (1 strip per box)
- Manufacturer: GlaxoSmithKline (Thailand) Ltd.
- Thai FDA registration: 1C 53/56 | ATC: R06AE07
Where to Buy Zyrtec
How to buy Zyrtec?
Order online at Intimo Life with nationwide delivery across Thailand in 1-3 business days. Discreet packaging — no product name on the outer box for your privacy.
⚠️ Disclaimer
The information on this page is for general informational purposes only and is not intended to replace professional medical advice, diagnosis, or treatment from a qualified doctor or pharmacist. If you have any questions about your symptoms or medication, always consult a doctor or pharmacist first.
References
- Simons FE, Simons KJ. Histamine and H1-antihistamines: celebrating a century of progress. J Allergy Clin Immunol. 2011;128(6):1139-1150. doi:10.1016/j.jaci.2011.09.005
- Rathinavelu S, et al. Cetirizine. StatPearls Publishing. Accessed April 2026. Available: https://www.ncbi.nlm.nih.gov/books/NBK557641/
- NHS. Cetirizine. NHS Medicines A–Z. Accessed April 2026. Available: https://www.nhs.uk/medicines/cetirizine/
- Drugs.com. Cetirizine: Drug Information. Accessed April 2026. Available: https://www.drugs.com/cetirizine.html
- MIMS Thailand. Zyrtec (cetirizine) prescribing information. GlaxoSmithKline (Thailand) Ltd. Accessed April 2026.
Frequently Asked Questions
Yes. Zyrtec is the original brand name (by UCB Pharma) and Cetirizine is the INN (generic name). The active ingredient is identical. Differences lie in the manufacturer and quality control standards.
Zyrtec causes significantly less drowsiness than 1st-generation antihistamines (e.g., Chlorpheniramine) due to lower CNS penetration. Some individuals may still experience mild sedation — test your personal response before driving.
Zyrtec begins working within 1 hour of ingestion, reaches peak effect at 1-2 hours, and maintains antihistamine activity for 24 hours — enabling convenient once-daily dosing.
Zyrtec can be taken with or without food — food does not significantly affect Cetirizine absorption. Taking it with food may help reduce stomach discomfort in sensitive individuals.
Both are 2nd-generation antihistamines. Zyrtec (Cetirizine) generally has a slightly faster onset. Telfast (Fexofenadine) has the lowest sedation profile in the class — preferred for those particularly sensitive to drowsiness.
Both contain Cetirizine 10 mg. Zyrtec is the original brand (UCB Pharma) with the most comprehensive research backing. Cetrizin is a bioequivalent generic at a lower price point — suitable for long-term users seeking cost efficiency.
Zyrtec can be used continuously for weeks to months in chronic allergic conditions without developing tachyphylaxis (tolerance) — a common issue with 1st-generation antihistamines. Periodic pharmacist assessment is still recommended.
Yes, with dose adjustment. Patients with CrCl 10-30 mL/min should reduce to 5 mg per day. Those with CrCl less than 10 mL/min or on dialysis should avoid use or consult a physician first.
Cetirizine is FDA Pregnancy Category B (no animal harm demonstrated), but human data is limited. It passes into breast milk in small amounts. Physician consultation is recommended before use during pregnancy or lactation.
Zyrtec reduces allergic rhinitis symptoms including nasal congestion and runny nose. However, it does not act as a direct decongestant. Severe congestion may require a nasal decongestant. It is not indicated as a cough suppressant.
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