Allertec

Quick links to important sections

Allertec

Selected form

Medically reviewed

Laura Arias

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Allertec

Property Description
Active ingredient Cetirizine Dihydrochloride
Form Tablet, Oral Solution, Drops
Pharmacological class Second-generation Antihistamine
Common purpose Symptomatic relief of allergic discomfort
Origin Synthetic metabolite of Hydroxyzine

What Type of Medicine is Allertec? (Identity and Classification)

Allertec is a pharmaceutical preparation whose primary active compound, Cetirizine Dihydrochloride, is classified as a potent, long-acting second-generation antihistamine. This drug type operates as a selective Histamine H₁ receptor antagonist, designed to interrupt the body's response to histamine. Clinically recognized for its efficacy, Cetirizine offers symptomatic relief from common allergic discomforts. As a synthetic compound, it is chemically derived as an active carboxylic acid metabolite of the first-generation antihistamine, Hydroxyzine. Unlike older compounds, second-generation agents are generally supported by pharmacological studies for possessing limited ability to cross the blood-brain barrier, which concentrates their anti-allergic action on the periphery, leading to a less disruptive profile.

Composition and Available Forms of Cetirizine Dihydrochloride (Structure and Form)

The medicinal effect is attributable solely to its core compound, Cetirizine Dihydrochloride, making it a highly focused, single-ingredient product. The compound belongs to the piperazine class and is formulated for oral (systemic use). The common pharmaceutical preparations for this medicine include the orally administered film-coated tablet, as well as liquid preparations such as the oral solution and drops. This variety ensures suitable options for a broad patient group, including those who may require the liquid form.

General Purpose of Allertec (Function and Benefit)

The general purpose of this medicine is to counteract the effects of histamine, the substance responsible for many allergic symptoms. By acting as a selective peripheral H₁ receptor antagonist, Cetirizine effectively blocks histamine from binding to its target receptors, inhibiting the processes that cause physical symptoms. This targeted mechanism provides sustained anti-allergic action, offering reliable relief from the physical discomforts associated with an allergic immune response.

What side effects are possible with Allertec?

Possible Side Effects and Safety Information

Regulatory documentation outlines the official safety characteristics of Allertec (Cetirizine Dihydrochloride) by classifying adverse reactions based on their observed frequency and the physiological system affected. The most frequently documented adverse reactions, classified as Common (affecting up to 1 in 10 people), often involve the Nervous System and General Disorders, including somnolence (drowsiness), fatigue, headache, and dry mouth.

Less frequent, or Uncommon effects (up to 1 in 100 people), include agitation, pruritus (itching), rash, and diarrhoea. Rare adverse reactions (up to 1 in 1,000 people) are those such as hypersensitivity reactions, convulsions, and documented instances of abnormal hepatic function (reversible increases in liver enzymes). Anaphylactic shock is classified as a very rare but serious adverse reaction.

Regulatory Safety Notes

Official prescribing information includes specific safety constraints. Caution is advised for patients with factors predisposing them to urinary retention and those with a history of epilepsy or risk of convulsions. The safety profile notes that effects on the central nervous system may be compounded by the concurrent use of alcohol or other CNS depressants. For specific patient groups, use is often contraindicated in individuals with severe renal impairment, and caution is advised for patients with pre-existing hepatic impairment. Regulatory documents also note that pruritus after discontinuation may be experienced following the cessation of long-term daily use.

Overdose and Emergency Response

Overdose and When to Seek Help

Official regulatory information describes the overdose profile of Allertec (Cetirizine Dihydrochloride) based on documented clinical manifestations and required emergency actions, emphasizing that a suspected overdosage requires immediate professional assistance or contact with a Poison Control Center.


Documented Overdose Manifestations

System Affected Officially Documented Signs
Central Nervous System Drowsiness (Somnolence), Fatigue, Tremor, Restlessness, Irritability
Cardiovascular Tachycardia (Fast Heart Rate)
Gastrointestinal Diarrhea, Abdominal Pain
Genitourinary Urinary Retention

Emergency Actions and Management Constraints

Regulatory authorities mandate that emergency medical care is required for overdosage, which is defined as ingesting a single dose of 50 mg or more. The officially recommended treatment is limited to symptomatic and supportive care. Procedural guidance notes that gastric lavage may be considered shortly after ingestion. The official regulatory documents confirm that no known specific antidote is available for Cetirizine overdosage, and the substance is not effectively removed by dialysis.

Overdosage in children is specifically documented to present with a different pattern, which may include increased agitation alongside systemic signs like tachycardia and urinary retention.

This profile defines the necessary response as urgent medical intervention to manage the documented clinical signs until the effects subside.

Therapeutic Uses of Allertec

What Allertec Treats: Main Uses and Benefits

The primary therapeutic role of Allertec (Cetirizine) is used to address certain distressing symptoms across key domains affected by various allergic reactions. It is commonly used to help manage groups of symptoms that may appear suddenly or intensify over time, providing support that helps ease the overall burden of symptoms. This includes relieving symptoms like sneezing, runny nose, and itching caused by allergies.

The medication is relevant for conditions involving episodic or fluctuating manifestations, such as seasonal and perennial allergic rhinitis, allergic conjunctivitis, and acute or chronic urticaria (hives). It helps address symptom clusters that may become intense or disruptive, including persistent sneezing, profuse runny nose, nasal and ocular pruritus, and the appearance of raised hives or associated swelling.

The supportive management is relevant in contexts involving heightened systemic burden. The medication is commonly used to help ease the overall symptom load during periods of heightened symptoms. Allertec may help patients cope more steadily with symptom fluctuations, providing symptomatic support when allergy signs interfere with daily functioning.

Quick Fact: Symptomatic Support for Pruritus
Allertec is commonly used to help ease intense body itching associated with chronic skin conditions like urticaria (hives) and certain other allergic dermatologic symptoms.

Regulatory References

  1. Cetirizine is used to relieve symptoms like sneezing, runny nose, and itching caused by allergies

Eligibility and Restrictions for Use

Who Can and Cannot Use Allertec?

Eligibility for using Allertec (Cetirizine Dihydrochloride) is strictly defined by regulatory criteria, focusing on age, organ function, and known hypersensitivities.

Contraindications (Who Must Not Use)

Contraindication Population
Hypersensitivity Patients with known allergy to cetirizine, hydroxyzine, excipients, or any piperazine derivatives.
Organ Impairment Patients with severe renal impairment (creatinine clearance less than 10 mL/min).
Age Infants under 6 months of age.

Eligibility and Restrictions

Use is generally permitted for adults and adolescents 12 years and older. Pediatric use is established for children starting at 6 months of age, often requiring specific liquid formulations for those under six years.

Patients with mild to moderate renal impairment are eligible, but this is considered restricted use and requires a reduction in the standard labeled dosage. Caution is advised for older adults due to the higher likelihood of decreased kidney function. Regulatory documents also state that use is not recommended during pregnancy or while breastfeeding, primarily as a precautionary measure, due to the drug's excretion into breast milk.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Allertec (Cetirizine Dihydrochloride) has a defined interaction profile established through formal studies reviewed by government health authorities. The information focuses strictly on potential additive effects and specific changes to the medicine's clearance.


Pharmacodynamic Interactions

The most significant documented interaction involves the potential for additive effects with substances that depress the Central Nervous System (CNS). Concurrent use of alcohol or other CNS Depressants is noted to potentially result in an additional reduction in alertness and further impairment of CNS performance. This interaction is classified as pharmacodynamic.


Pharmacokinetic Interactions

Co-administration with Theophylline (at a daily dose of 400 mg) has been documented to cause a statistically significant decrease in the clearance of cetirizine—a pharmacokinetic interaction. This effect may result in marginally increased systemic exposure to the medicine. Conversely, formal studies confirmed no clinically significant pharmacokinetic interaction with several commonly tested medications, including Azithromycin, Erythromycin, Cimetidine, Ketoconazole, and Pseudoephedrine.


Food and Administration Constraints

Taking Allertec with food does not reduce the overall amount of medicine absorbed (bioavailability), but it can delay the rate of absorption, affecting the time to reach peak concentration. Official regulatory documentation does not specify mandatory temporal separation rules for administration with food or other medicinal products.

Mechanism of Action

How Allertec Works: Pharmacodynamic Mechanism

Allertec (cetirizine) functions as a selective antagonist of the peripheral Histamine-1 ( H1) receptor. It engages defined biological targets by binding competitively to H1 receptors found on various cell surfaces, including those of the vascular endothelium and smooth muscle. This interaction modulates the initial signaling sequence triggered by histamine, reducing downstream effects resulting from excessive mediator activity and influencing the activity state within targeted physiological pathways.

Mechanistically, the compound also modifies early molecular steps that shape systemic outcomes by regulating processes driven by distinct signaling patterns beyond the primary receptor block. It influences pathways that limit the mobilization and activation of inflammatory cells, such as eosinophils, which may escalate under certain conditions. Furthermore, due to its low lipid solubility and minimal transport across the blood-brain barrier, it primarily affects systems where specific transmitters dominate outside the central nervous system, facilitating targeted pathway modulation predominantly in the periphery.

Dosage and Administration Information

How to Use Allertec: Administration Guidelines

The usage of Cetirizine Dihydrochloride (Allertec) follows standardized dosing and administration protocols.


Administration Protocol

Official Instruction Domain Regulatory Guidelines
Route of Administration Primarily Oral (PO) via tablets or solutions. An Intravenous (IV) injection is an approved route in certain jurisdictions for acute conditions.
Standard Dosing & Frequency The standard adult dose (12 years and older) is 10 mg, taken once daily. The maximum recommended oral dose is 10 mg per 24 hours.
Timing in Relation to Meals Oral formulations may be administered with or without food.
Dose Adjustment Rules A reduced dose of 5 mg once daily is required for patients with moderate to severe renal (kidney) impairment and is often suggested for older adults (age 65 and older).
Missed Dose Rule If a dose is missed, the instruction is to skip the forgotten dose and resume the schedule at the next usual time. Do not double the dose.

Official Procedural Summary

The administration protocol is centered on a once-daily frequency and a 10 mg maximum daily limit for oral use. This protocol includes dose modifications based on the patient's age and renal function status. Correct use of liquid forms requires a calibrated dosing device to ensure precise measurement.

Recent Clinical Evidence

Overview of Clinical Research

Allertec (cetirizine) is a second-generation, selective H1-receptor antagonist. Clinical evidence from numerous studies and systematic reviews supports its use for the symptomatic relief of various allergic conditions, including seasonal allergic rhinitis (hay fever), perennial allergic rhinitis, and chronic idiopathic urticaria (hives). Research has demonstrated that the drug acts rapidly, with significant inhibition of the allergic response often observed within 20 minutes to one hour of oral administration, and this effect typically lasts for 24 hours.

Efficacy in Allergic Conditions

Comparative clinical trials have shown that second-generation antihistamines, including cetirizine, are generally effective in reducing key histamine-related symptoms such as sneezing, rhinorrhea (runny nose), ocular (eye) symptoms, and pruritus (itching) in adult and pediatric populations (typically age 6 months and older, depending on formulation and regional guidelines).

Safety and Tolerability Profile

As a second-generation agent, cetirizine is widely studied for its low tendency to cross the blood-brain barrier. This characteristic is associated with a reduced risk of sedation and cognitive impairment compared to first-generation antihistamines. However, drowsiness remains a commonly reported side effect, and the rate of somnolence has been noted in some studies as being higher than with certain other second-generation agents. The drug is predominantly eliminated by the kidneys, which is a factor considered when used in individuals with reduced renal function.

Study Focus Primary Findings Comparative Aspect
Allergic Rhinitis Associated with improvement in total nasal and non-nasal symptom scores. Often used as an active comparator (benchmark) against new allergy treatments.
Chronic Urticaria Shown to reduce the severity of hives and associated itching. Considered a first-line treatment option by major clinical guidelines.

Key Studies & References

  1. Cetirizine, loratadine, or placebo in subjects with seasonal allergic rhinitis: effects after controlled ragweed pollen challenge in an environmental exposure unit
  2. Chronic urticaria: off-label doses of cetirizine (NICE Evidence Summary)

Frequently Asked Questions (FAQ)

Common questions about Allertec (FAQ)

Q: Does Allertec cause drowsiness for most people?

Regulatory documents state that somnolence (drowsiness) is classified as a Common adverse reaction. This means that, based on clinical data, this effect may be observed in up to 1 in 10 people. The occurrence of drowsiness is confined to the official frequency reported in trials.

Q: What happens if I stop taking Allertec suddenly?

Regulatory information includes a warning that patients who cease using the medicine after long-term daily use—typically lasting a few months or more—may experience a reaction. This reaction is reported as rare but severe itching (pruritus). The management of this reaction is usually discussed with a healthcare provider.

Q: Is there an issue with having an alcoholic drink while using Allertec?

Official regulatory warnings advise caution regarding the concurrent use of alcohol with this medicine. Combining the two may lead to an additional reduction in alertness and further impairment of Central Nervous System (CNS) performance. This is classified as a known interaction.

Q: How long does the effect of one dose of Allertec usually last?

Studies and official information indicate that the anti-allergic effect of a single dose of the medicine typically lasts for 24 hours. This sustained action is related to its classification as a long-acting antihistamine.

Q: Do food or certain supplements affect how Allertec is absorbed?

According to the official product information, the medicine may be taken with or without food. Taking it with food does not change the overall amount of medicine absorbed by the body (bioavailability). However, consuming it with a meal can slightly delay the rate at which the medicine reaches its highest concentration.

Q: Can Allertec affect alertness or driving ability?

Due to the potential for officially recognized adverse effects such as drowsiness (somnolence) and fatigue, regulatory information advises caution and awareness when performing tasks requiring complete mental alertness, such as driving or operating heavy machinery.

Q: Why do people sometimes feel restless or agitated after taking certain allergy medicines like Allertec?

Official regulatory documentation lists agitation as an Uncommon adverse reaction associated with this medicine. This means that the effect is seen in clinical trials, but typically affects up to 1 in 100 people.

Q: Does Allertec contain gluten or lactose?

Official labeling for the standard tablet form often lists lactose as an inactive ingredient, or excipient, within its composition. The presence or absence of gluten in the various formulations is also specified in the full regulatory composition documents.

Q: What do patient information leaflets say about taking Allertec with food?

Patient information states that the medicine may be taken with or without food. Taking the medicine with a meal may result in a slight delay in the rate of absorption, but the total amount of medicine absorbed by the body remains the same.

Q: Why is Allertec available over the counter?

The medicine was approved for an Over-the-Counter (OTC) switch by the U.S. Food and Drug Administration (FDA) in 2007. This decision was based on a regulatory determination that the drug's established safety and efficacy profile allows for its appropriate use without the necessity of a prescription.

Q: What is the general recommended age for someone to start taking Allertec?

According to official documents, the medicine is contraindicated (must not be used) in infants under 6 months of age. Specific liquid doses are approved for children starting at 6 months of age, and is approved for use in adults and adolescents 12 years and older.

Q: Are there any long-term research studies on the use of Allertec?

The medicine is approved for the treatment of chronic idiopathic urticaria and perennial allergic rhinitis. These are conditions that require long-term management, and the regulatory approval relies on data demonstrating its effectiveness and safety over extended treatment periods.

Q: Is Allertec linked to any weight changes?

Regulatory documentation lists weight gain as a recorded adverse reaction. This is classified in the Rare category, meaning that based on official reports, it may affect up to 1 in 1,000 people.

Q: Can Allertec cause a dry mouth or nose?

Official regulatory documents list dry mouth as a Common side effect, meaning it may affect up to 1 in 10 people. Conversely, dry nose is not typically listed among the primary categories of adverse reactions.

Q: Does Allertec have a reputation for causing 'rebound' symptoms if discontinued?

Official regulatory warnings note a risk of pruritus (severe itching) that has been reported by patients who stop the medicine after long-term daily use. The official language used focuses on this specific adverse reaction following cessation, not the general term 'rebound'.

Q: Why might Allertec be prescribed by a doctor instead of just bought OTC?

A doctor's prescription is often needed for patients who require an officially recommended reduced dosage. This is mandated for individuals with conditions such as renal (kidney) or hepatic (liver) impairment, where the standard Over-the-Counter (OTC) instructions may be unsuitable or less clear.

Q: Is it possible to become dependent on Allertec?

Official regulatory warnings focus on the risk of pruritus (severe itching) that has been reported by patients who cease the medicine after long-term daily use. The official language used in these regulatory documents does not use the term 'dependence' to describe this reaction.

Q: What evidence is there supporting the claims about Allertec's effectiveness?

The medicine is approved and supported by clinical trials and systematic reviews. This evidence confirms its symptomatic relief for conditions like seasonal allergic rhinitis and chronic idiopathic urticaria, aligning with the official therapeutic indications.

Q: Can Allertec cause upset stomach or digestive issues?

Regulatory documents list diarrhoea as an adverse reaction. This is classified as an Uncommon effect, meaning that based on official reports, it may affect up to 1 in 100 people.

Q: Can Allertec make my anxiety worse?

Official regulatory documentation lists agitation as an adverse reaction. This effect is classified as Uncommon, meaning it may affect up to 1 in 100 people, according to clinical data.

Q: Do children usually experience different side effects from Allertec than adults?

Clinical trial data reviewed for regulatory approval shows that certain common adverse reactions in children may occur at different frequencies than those seen in adult studies. Specific side effects noted in pediatric populations include somnolence and nasopharyngitis (cold-like symptoms).

Q: Is there a maximum time frame that a person should use Allertec?

Regulatory documents do not define a maximum time limit for the use of the medicine. However, they include a specific warning that severe itching may occur upon cessation following long-term daily use (typically a few months or more).

Q: Can Allertec make my vision blurry?

Visual disturbances, such as accommodation disorder or blurred vision, are listed in regulatory documents as Rare adverse reactions. This means that based on official reports, this effect may be seen in up to 1 in 1,000 people.

Q: Is Allertec used to treat pet allergies?

The official therapeutic indications for the medicine include the symptomatic relief of perennial allergic rhinitis. This condition covers the allergic symptoms caused by indoor allergens, such as pet dander, dust mites, and mold.

How should Allertec be stored and disposed of?

How to Store and Dispose of Allertec (Cetirizine Dihydrochloride)

Allertec must be stored under specific conditions to maintain its integrity and efficacy, as defined in regulatory labeling.


Required Storage Conditions

  • Temperature: Store at Controlled Room Temperature, generally between 20 C to 25 C (68 F to 77 F). Excessive heat and high humidity must be avoided.
  • Protection: Some liquid forms require protection from light. The product container must be kept tightly closed and should not be used if the blister unit is broken.
  • Child Safety: It is strictly required to keep out of the sight and reach of children.

Disposal Instructions

Unused or expired Allertec must be disposed of in accordance with local requirements for pharmaceutical waste. This often involves using a community drug take-back program. If no program is available, the FDA recommends mixing the medicine with an undesirable substance before discarding it in a sealed container in the household trash. Do not throw the product into wastewater.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

Available in countries:

Equivalent of Allertec found in:

A-Z Index: