Alercet

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Medically reviewed

Rosario Oropesa

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 Alercet

Quick Facts

Property Description
Active ingredient Cetirizine Hydrochloride
Form Tablet, Oral Solution, Syrup
Pharmacological class Second-generation Antihistamine
General purpose Relief of allergic discomforts
Origin Synthetic, Piperazine derivative

Composition, Class, and the Identity of Cetirizine

Alercet is a synthetic single-ingredient pharmaceutical preparation whose identity is fundamentally derived from its active ingredient, Cetirizine Hydrochloride. This substance is formally classified within the pharmacological class as a Histamine H₁ Receptor Antagonist, positioning it as a second-generation Antihistamine. It is a piperazine derivative and is recognized as the pharmacologically active metabolite of Hydroxyzine. The classification as a second-generation agent is critical, as these compounds are designed for highly selective antagonism of peripheral H₁ receptors, a characteristic feature that differentiates it from older compounds. This specific composition helps provide relief from allergic symptoms while minimizing effects on alertness.


Available Forms and General Therapeutic Purpose

The medicine is intended for systemic (Oral) administration and is available in several drug forms to accommodate patient needs, including the widely used tablet, as well as an oral solution and syrup suitable for the pediatric population. The general therapeutic purpose of this medication is to provide relief by modulating the body's overactive inflammatory response to allergens, which underlies common allergic conditions and hypersensitivity reactions. The substance functions as an anti-allergic agent, establishing the medicine as a tool for controlling the effects of an allergic response within the body. It achieves this by employing a targeted blockade of the histamine chemical messenger, preventing the cellular cascade that results in characteristic physical discomforts.

What side effects are possible with Alercet?

The safety profile of Alercet (Cetirizine Hydrochloride) is formally categorized in regulatory documents based on the frequency and system of the body affected, defining the drug's known risks.

Adverse Reaction Scope

Adverse reactions are classified into System-Organ Classes (SOCs), which include Nervous system disorders, Gastrointestinal disorders, Psychiatric disorders, and Immune system disorders.

Frequency Classification Examples of Documented Effects
Common (1% to <10%) Somnolence (drowsiness), Headache, Fatigue, Dizziness, Dry mouth, Nausea
Rare (0.01% to <0.1%) Hypersensitivity, Convulsions, Tachycardia, Abnormal hepatic function, Urticaria
Very Rare (<0.01%) Anaphylactic shock, Syncope, Tremor, Oculogyration, Urinary retention
Not Known Suicidal ideation, Amnesia, Hepatitis, Vertigo

Serious Adverse Reactions documented in official labeling include Anaphylactic shock, Convulsions, and reports of Abnormal hepatic function (e.g., elevated transaminases). Additionally, a Not Known frequency includes post-marketing observations such as Suicidal ideation and Memory impairment.

Population-Specific Safety Considerations

Official regulatory documents require caution for specific patient groups:

  • Renal Impairment: Drug clearance is reduced. Use is contraindicated in individuals with severe renal impairment (creatinine clearance <10 mL/min).
  • Hepatic Impairment: Clearance may be reduced, and dose adjustment is generally advised.
  • Duration-Related Pattern: Severe generalized pruritus (itching) and/or urticaria have been reported upon stopping treatment after regular, long-term use.

Connection to the Overall Safety Profile

The regulatory safety data provides a structured, descriptive framework that allows for the assessment of expected versus rare adverse events across various body systems. By documenting serious risks and constraints related to pre-existing conditions (e.g., renal impairment) and the potential for a discontinuation-related reaction, the official profile defines the known boundaries of risk for this medication.

Overdose and Emergency Response

The official regulatory profile for an overdose of Alercet (Cetirizine Hydrochloride) details a range of clinical manifestations primarily involving the central nervous system. Documented presentations include both CNS depression—such as somnolence, headache, and dizziness—and, in some cases, paradoxical CNS excitation—including restlessness, agitation, and irritability.

Severe outcomes that necessitate immediate action are formally classified as life-threatening symptoms, such as convulsions (seizures), profound respiratory difficulty, or collapse. The potential for serious cardiac effects, including arrhythmias, is a concern with substantial ingestions.

Mandatory Emergency Actions

The mandatory instruction in regulatory labeling is to seek immediate medical help for any suspected overdose. Contact with a Poison Control Center is required right away. Emergency services must be contacted immediately if the patient is unresponsive, has collapsed, or is experiencing a seizure or severe trouble breathing.

Management and Specific Considerations

Official guidelines specify that treatment is entirely symptomatic and supportive, as no known specific antidote is available. Management procedures may involve the consideration of decontamination measures like activated charcoal and may require hospital cardiac monitoring in cases of massive ingestion. Population-specific notes confirm that children may exhibit a more severe and atypical presentation, while the elderly have a prolonged drug half-life, which affects clearance in an overdose situation.

Therapeutic Uses of Alercet

Quick Facts

  • Relief from Allergic Rhinitis: May help alleviate symptoms associated with seasonal and perennial allergic rhinitis, such as sneezing and a runny nose.
  • Urticaria Management: Indicated for the management of the uncomplicated skin manifestations of chronic idiopathic urticaria (hives).
  • Symptom Relief: Provides support in addressing common allergy discomforts, including watery eyes and skin itching.

Alercet is used in the therapeutic domain of allergy management to help relieve symptoms associated with various allergic conditions. The medication may support the reduction of discomfort linked to seasonal allergic rhinitis, commonly known as hay fever, as well as perennial allergic rhinitis, which is caused by year-round allergens like dust mites and pet dander.

This medicine is also indicated for the management of uncomplicated skin manifestations of chronic idiopathic urticaria, or hives, and may help mitigate symptoms such as itching and the appearance of hives. For patients experiencing common allergy symptoms, Alercet may offer relief from sneezing, a runny nose, an itchy throat, and watery or itchy eyes. It is important for individuals to consult with a healthcare professional to determine if this treatment is appropriate for their specific condition.

Eligibility and Restrictions for Use

Who can and cannot use Alercet?

Alercet (Cetirizine Hydrochloride) is subject to official population eligibility rules defined by regulatory authorities worldwide.

Absolute Contraindications

Use is strictly contraindicated for patients with a known history of hypersensitivity to cetirizine, its parent compound hydroxyzine, or any piperazine derivatives. It is also contraindicated in patients with severe renal insufficiency, defined as a Creatinine Clearance less than 10 mL/min.

Age and Formulation Eligibility

The medicine is approved for use in adults and adolescents and is established for the pediatric population starting at 6 months of age for certain uses, typically using liquid formulations. The film-coated tablet formulation is not recommended for children under six years old.

Conditional Eligibility and Restrictions

Patients with moderate renal impairment are eligible but require a restriction in use, necessitating a dose adjustment due to the drug’s renal elimination. Caution is formally required for patients with predisposing factors for urinary retention and for individuals with epilepsy or who are at risk of convulsions. Use during breastfeeding is not recommended, and during pregnancy it should only be used if clearly necessary.

What should I know about interactions with other medicines?

Alercet's (Cetirizine Hydrochloride) official regulatory profile documents specific interaction patterns concerning pharmacodynamic enhancement, pharmacokinetic modification, and constraints related to co-administered substances or physiological states. The information presented here is based strictly on authoritative government drug labels.

Pharmacodynamic Interactions

The co-administration of Alercet with alcohol or other Central Nervous System (CNS) depressants is associated with a documented pharmacodynamic interaction. This combination may result in an additive reduction in alertness and potential impairment of performance in sensitive individuals, as formally stated in regulatory warnings.

Pharmacokinetic and Absorption Dynamics

A specific pharmacokinetic interaction is documented regarding co-administration with theophylline. Studies using a 400 mg dose of theophylline once daily demonstrated a 16% decrease in the clearance of cetirizine. Regulatory documents also specify that concurrent administration with food alters the drug's absorption: while the overall extent of absorption (AUC) remains unchanged, the rate of absorption is officially documented to be decreased (peak concentration is reduced and the time to reach it is delayed).

Physiological State Constraints

The drug’s clearance, which is primarily managed through renal excretion, is officially noted to be subject to alteration in patients with specific physiological conditions. Constraints are documented for individuals with hepatic impairment or renal impairment, where altered organ function results in modified drug clearance that requires attention as per the regulatory guidelines.

Mechanism of Action

Selective H1 Receptor Antagonism

The mechanism of Alercet (Cetirizine) is strictly focused on inhibiting the action of histamine, a key chemical mediator released during a hypersensitivity reaction. The drug functions as a high-affinity competitive antagonist of the peripheral Histamine H1 receptors. Cetirizine binds to these receptors, stabilizing them in an inactive state and effectively blocking endogenous histamine from initiating the signaling cascade associated with acute peripheral responses.


Intervention in Vascular and Sensory Pathways

The antagonism of peripheral H1 receptors directly intervenes in the function of the microvascular and sensory nervous systems. By interrupting histamine signaling on endothelial cells, the drug limits the histamine-driven increase in vascular permeability (fluid leakage), and by blocking receptors on sensory nerve endings, it suppresses the signaling responsible for the transmission of pruritus. This mechanism results in inhibition of fluid extravasation and nerve excitation.


Minimal Central Nervous System Interaction

A defining mechanistic feature is the drug's limited ability to cross the blood-brain barrier (BBB) due to its chemical structure and its role as a potential substrate for P-glycoprotein efflux transporters. This high peripheral selectivity restricts its H1 antagonistic effect primarily to tissues outside the brain and spinal cord, thus limiting interaction with central histaminergic pathway functions.

Dosage and Administration Information

Alercet (Cetirizine Hydrochloride) is administered via the oral route for routine use, utilizing forms such as tablets, oral solution, or syrup. The injectable form, provided as a 10 mg/mL solution, is also utilized for intravenous (IV) administration in acute settings under medical supervision. The medicine is primarily used on a once-daily schedule and may be taken with or without food.

Standard Administration and Dosing

For adults and adolescents (aged 12 and older), the dose is typically 10 mg once daily, which is the maximum recommended dose in a 24-hour period. A lower dose of 5 mg once daily may be used as a starting point for milder symptoms. Pediatric dosing is tiered by age; children aged 6 to 11 years commonly receive 5 mg to 10 mg per day. Liquid formulations, such as the solution or syrup, must be measured using a calibrated dosing device to ensure accurate administration. If a dose is missed, it should be skipped if close to the next scheduled dose, and a double dose must be avoided.

Population-Specific Use Adjustments

Dose adjustments are required for specific populations. For older adults, a starting oral dose of 5 mg once daily is often recommended. A reduction in dosage is necessary for adult patients with impaired kidney function, as the drug is primarily eliminated via renal excretion. For instance, individuals with moderate renal impairment (creatinine clearance 30–49 mL/min) are typically reduced to 5 mg once daily, and those with severe impairment to 5 mg once every two days.

Recent Clinical Evidence

Research evidence / Overview of Studies for Alercet (Cetirizine)

The research evidence primarily consists of controlled clinical trials and meta-analyses that were used to explore patterns of symptoms in allergic conditions. These studies contribute to the broader evidence landscape. Findings describe group patterns, not personal outcomes.


Evidence Base for Seasonal Allergic Rhinitis (Hay Fever)

Research for seasonal allergic rhinitis (hay fever) primarily consists of short-term, randomized controlled trials (RCTs). These studies were conducted during periods of increased symptom activity. Outcomes studied included the measurement of nasal and ocular symptoms, often grouped into a Total Symptom Score (TSS). Findings describe patterns observed in the studies and research highlights changes measured when compared to a non-active treatment (placebo) or was evaluated in comparison to certain other antihistamine compounds. The follow-up durations were limited in many key studies, meaning long-term effects are not fully established regarding efficacy maintenance.


Evidence Base for Chronic (Perennial) Allergic Rhinitis

This evidence base includes studies with a longer follow-up duration compared to seasonal allergy trials. Research examined symptom change over several months in conditions where symptoms may vary in intensity throughout the year. Research describes group patterns related to symptom changes across intermediate time intervals, typically up to six months. However, data for certain groups remain insufficient, particularly in addressing patients with refractory symptoms whose perennial symptoms remain uncontrolled by standard care. Comparative evidence is lacking showing how this drug fares against all available alternatives in identical long-term settings.


Research on Chronic Idiabatic Urticaria (Hives)

The medicine was studied for conditions involving periods of heightened symptoms, such as Chronic Idiopathic Urticaria (CIU). The research primarily consists of short-term, randomized controlled trials. Outcomes measured were objective signs of skin reaction, such as a Hives (Wheal) Count, alongside subjective patient-reported outcomes related to itching severity. Data are still emerging for patients whose CIU symptoms do not respond to standard doses, and the certainty remains low regarding the use of non-standard, higher dosing.


Current Evidence Gaps and Uncertainties

Despite the volume of research, certain aspects of the evidence landscape remain insufficiently studied or uncertain. Subgroup findings are uncertain or are not consistently available for all age groups across all licensed indications. The overall evidence contributes to the broader evidence landscape, but the research does not determine whether an individual will respond similarly to the group findings.

Key Studies & References

  1. Cetirizine for the treatment of allergic diseases in children: A systematic review and meta-analysis
  2. H1-antihistamines for chronic spontaneous urticaria: an abridged Cochrane Systematic Review
  3. Cetirizine in Children with Coexisting Allergic Rhinitis and Asthma: A Randomized Trial (used for pediatric data and long-term observation)

Frequently Asked Questions (FAQ)

Common questions about Alercet (FAQ)


Q: How long does it take for Alercet to start working?

Studies and official information indicate that the time required to reach the maximum concentration of the medicine in the body (Tmax) is approximately one hour after it is taken orally. Clinical studies have shown that relief of some allergic symptoms may begin within a range of 20 to 60 minutes.


Q: How many hours does the effect of Alercet typically last?

The drug is officially administered on a once-daily schedule. This dosing pattern reflects that the effects of the medicine are generally described in regulatory documents as lasting for approximately 24 hours.


Q: If I miss a dose of Alercet, what should I do?

Official guidance describes the action to be taken when a dose is missed: that the dose may be taken as soon as it is remembered. If, however, it is already almost time for the next scheduled dose, the missed dose should be skipped entirely. Regulatory warnings strictly state that double or extra doses must not be taken, and the regular administration schedule should be resumed.


Q: Can Alercet affect my ability to drive or operate machinery?

Regulatory documents state that somnolence (drowsiness) or sedation may occur in some individuals using the medication. Documents include warnings cautioning against performing activities that require full mental alertness, such as driving a car or operating potentially dangerous machinery.


Q: What happens if you take Alercet for longer than recommended?

Official regulatory documents do not define a specific long-term risk associated with the continuous use itself. However, post-marketing safety data reports that severe generalized pruritus (itching) and/or hives have been noted in some cases upon stopping the medicine after regular use over extended periods of time.


Q: Does Alercet make you feel sleepy or drowsy?

Yes, official regulatory safety data lists somnolence (drowsiness) as a Common adverse reaction. This effect is reported in a small percentage of patients (1% to less than 10%) who participated in clinical trials.


Q: Can Alercet be used for skin rashes or hives?

Yes, regulatory authorities have approved the medication for the treatment of symptoms associated with Chronic Idiopathic Urticaria (CIU). This condition refers to chronic hives with an unknown cause.


Q: Can Alercet cause weight gain?

Official safety documents list weight increase under the body system adverse events, within a category where the frequency is often not established. The regulatory listing of this event does not confirm a known frequency or a causal relationship to the medicine.


Q: Is it true that Alercet can affect your mood?

Regulatory safety data documents Psychiatric disorders as an adverse reaction class observed in post-marketing surveillance. Specific reactions that have been reported include feelings of nervousness, anxiety, depression, and abnormal thinking.


Q: Can children use Alercet for their allergies?

Yes, the medicine is approved for use in the pediatric population. It is authorized for some uses in children starting at 6 months of age, and different formulations are authorized for use across various pediatric age ranges.


Q: Is Alercet safe for older adults or seniors?

Official documents state that use in older adults is subject to caution because drug clearance (how the body eliminates the medicine) may be slower. The medicine's official label advises that a reduction in strength may be necessary for patients aged 65 years and older.


Q: Is Alercet available without a prescription?

Yes, the medication is authorized for sale as both a prescription (Rx) drug and as an over-the-counter (OTC) medicine in various jurisdictions. The availability often depends on the specific dosage strength or formulation.


Q: What is the difference between a prescription and over-the-counter version of Alercet?

The main differences between prescription and over-the-counter versions are generally related to the approved indications, the specific dosage strengths available, and the formulations. Some liquid or injectable forms may remain prescription-only, while tablets are often available OTC.


Q: Can Alercet be taken with common pain relievers?

Regulatory safety documents generally do not list a direct interaction between this medication and the active ingredients in most common, single-ingredient pain relievers such as ibuprofen or acetaminophen. However, caution is always advised when taking the medication with combination products that contain other drowsy-causing ingredients.


Q: Are there any specific foods or drinks that should be avoided when taking Alercet?

The only beverage associated with a documented pharmacodynamic interaction is alcohol, which may cause an additive reduction in alertness. While food can slow the rate at which the medicine is absorbed, the overall amount of drug that enters the body remains unaffected.


Q: Can Alercet make anxiety or nervousness worse?

Regulatory safety data lists both anxiety and nervousness as documented adverse reactions. These effects are classified within the Psychiatric disorders system-organ class in official regulatory documents.


Q: Are there different strengths of Alercet available?

The medication is available in several forms, including oral tablets, oral solution, and syrup. The available strengths commonly include 5 mg and 10 mg tablets, with a 20 mg strength authorized in some jurisdictions.


Q: Can Alercet be used for the common cold?

The official regulatory indications for this medicine are limited to treating symptoms of allergic conditions such as allergic rhinitis (hay fever) and chronic hives. Its use is not supported by regulatory indications for the treatment of symptoms associated with the common cold.


Q: Why do people sometimes say Alercet stops working after a while?

Regulatory documentation notes that the drug is generally less prone to tolerance—a reduced response over time—compared to older types of antihistamines. The official product label does not explicitly define or confirm the phenomenon of a rapidly decreasing response (tachyphylaxis).


Q: Can Alercet be taken with other cold or flu medications?

Official regulatory warnings describe the potential for interactions when the medicine is used with other cold or flu medications that may contain alcohol or other Central Nervous System (CNS) depressants. Combining these substances may result in an additive reduction in alertness.


Q: Is Alercet known to interact with grapefruit juice?

The regulatory documents do not list any specific interaction or contraindication related to consuming grapefruit juice while taking this medication. This particular warning is often associated with other types of allergy medicines.


Q: Can I take Alercet if I have high blood pressure?

Regulatory safety data does not list high blood pressure as a contraindication for the single-ingredient formulation of the medicine. Regulatory documents indicate that caution may be necessary when using combination products (those that contain a decongestant) as the decongestant ingredient may be a contraindication for patients with high blood pressure.


Q: What is the general safety classification of Alercet?

Regulatory authorities generally classify this drug as having a favorable risk/benefit profile suitable for use as an an over-the-counter (OTC) antihistamine. Under the European Union’s chemical safety standards, the core ingredient is officially listed as Not classified regarding general danger.


Q: What is the official purpose of Alercet as described by regulatory agencies?

The official regulatory indications describe the medication as being used for the relief of symptoms associated with seasonal allergic rhinitis (hay fever), perennial allergic rhinitis (year-round allergies), and chronic idiopathic urticaria (hives).


Q: Can Alercet cause dependence or addiction?

Regulatory safety reviews state that there is no history of a withdrawal syndrome documented for this drug after stopping its use. True physical dependence is not typically a concern with this class of second-generation antihistamines.


Q: What kind of interactions can happen between Alercet and herbal supplements?

Regulatory information documents the potential for caution because herbal remedies and supplements are generally not formally tested for interaction with this drug. Caution is specifically advised with any products that may cause side effects similar to the drug, such as drowsiness, dry mouth, or difficulty with urination.


Q: What are the main risks associated with taking Alercet?

The main risks described in regulatory documents include the potential for Central Nervous System (CNS) effects such as drowsiness and dizziness. Serious adverse reactions such as anaphylactic shock or convulsions have been reported. The medicine is also contraindicated in patients with severe kidney insufficiency.

How should Alercet be stored and disposed of?

Storage and Disposal Requirements

Alercet (Cetirizine Hydrochloride) must be stored according to official regulatory specifications to maintain its stability and effectiveness.

Official Storage Conditions

Requirement Specific Condition
Temperature Store at controlled room temperature: 20 C to 25 C (68 F to 77 F). Avoid excessive heat (above 40 C) or freezing.
Environmental Protect from light and high humidity.
Container Keep the medicine in its original, tightly closed container. Do not use if the product seal or packaging is broken.
Child Safety Mandatory requirement: Keep out of the reach of children.

Disposal

Disposal of unused or expired Alercet should follow local regulations. The preferred method is using official drug take-back programs. If these are unavailable, the medication should be mixed with an undesirable substance, placed in a sealed container, and discarded in the household trash. The product should not be flushed down a sink or toilet.

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

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