Histec

Quick links to important sections

Medically reviewed

Marina Burgos

Last updated on 10/01/2026

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 Histec

Histec is a brand name for a medication used to relieve symptoms associated with allergies. The active ingredient in the most common formulation of Histec is cetirizine dihydrochloride (cetirizine HCl), which is classified as a second-generation antihistamine.

Core Function and Classification

As a non-sedating, second-generation H1-receptor antagonist, cetirizine works by selectively blocking the action of histamine, a natural substance the body releases during an allergic reaction. By blocking histamine, Histec helps to alleviate common allergy symptoms. Its mechanism of action is clinically recognized to be highly selective for peripheral H1 receptors, which is why it generally causes less drowsiness compared to older, first-generation antihistamines.

Key Differentiating Factors

While Histec is one of many brands containing cetirizine (other popular brands include Zyrtec and Piriteze Allergy), it is typically available as a film-coated tablet in various strengths, such as 10 mg. This is commonly an over-the-counter (OTC) medication in many countries, though the specific legal status and available formulations (e.g., tablet, syrup) may vary depending on the local manufacturer and country of distribution. Histec is primarily positioned for the relief of symptoms related to:

  • Seasonal and perennial allergic rhinitis (hay fever, dust mite allergy).
  • Chronic idiopathic urticaria (long-term hives and associated itching).

Unlike combination products that may include a decongestant, Histec typically provides only antihistaminic relief. For instance, a patient experiencing sneezing and a runny nose due to spring pollen would typically use Histec for symptom management.

What side effects are possible with Histec?

Possible side effects and safety information

The official safety documentation for Histec (cetirizine) outlines the adverse reactions according to frequency and the body system affected, based on regulatory standards.

Frequency-Classified Adverse Reactions

The most frequently observed adverse reactions are classified as Common (may affect up to 1 in 10 people) and typically involve the central nervous system or gastrointestinal tract. These commonly listed effects include somnolence (drowsiness), fatigue, headache, dizziness, dry mouth, and nausea.

Reactions are also classified as Uncommon, Rare, or Very Rare as severity generally increases, though this is not always the case. Uncommon effects include pruritus (itching) and rash. Rare adverse reactions include serious hypersensitivity responses, such as oedema (swelling) and convulsions, as well as abnormal liver function tests. Very Rare documented reactions include anaphylactic shock, angioneurotic oedema, and urinary retention.

Safety Considerations and Limitations

The regulatory safety profile notes specific constraints related to patient health status. Cetirizine is contraindicated in individuals with severe renal disease (creatinine clearance less than 10 mL/min). Dose review is typically required for patients with moderate to severe renal impairment. Furthermore, caution is advised in epileptic patients or those at risk of convulsions, and when using the medicine concurrently with alcohol or other central nervous system depressants, due to potential additive effects.

Time-related patterns, such as the reporting of intensified itching or hives upon discontinuation of the medicine after long-term use, are also noted in official regulatory texts.

Overdose and Emergency Response

Overdose and when to seek help

Overdose with the active ingredient cetirizine (Histec) is primarily characterized by effects on the Central Nervous System (CNS). Documented overdose presentations may involve CNS depression, manifesting as pronounced somnolence (drowsiness), sedation, fatigue, or stupor. Conversely, some individuals, particularly children, may experience signs of CNS excitation, including restlessness, irritability, and tremor.

Beyond CNS effects, other physical manifestations documented in regulatory sources include tachycardia (fast heart rate), mydriasis (dilated pupils), urinary retention, and gastrointestinal symptoms such as nausea, abdominal pain, and diarrhoea. Severe outcomes such as convulsions require immediate attention.


Emergency Actions and Management

It is officially mandated that any suspected overdose requires the individual to seek immediate medical attention. Users must contact a Poison Control Center right away or call emergency services if severe symptoms like collapse, seizure, or inability to be awakened occur.

The regulatory documents state that no known specific antidote to cetirizine exists. Management is therefore strictly symptomatic and supportive treatment. Healthcare professionals may consider procedures like gastric lavage for recent ingestion. Dialysis is noted to be ineffective for removing the substance from the body.

Therapeutic Uses of Histec

Main Uses and Therapeutic Applications

Histec is an antihistamine medication primarily used to manage symptoms associated with various allergic conditions. Its active mechanism focuses on blocking H1 receptors to reduce the physiological effects of histamine release.

Allergic Rhinitis

Histec is commonly utilized for the symptomatic relief of both seasonal and perennial allergic rhinitis. It addresses upper respiratory symptoms triggered by allergens such as pollen, dust mites, or animal dander. Key symptoms managed include:

  • Nasal congestion and sneezing: Reducing the inflammation and irritation of the nasal passages.
  • Rhinorrhea: Controlling excess mucus production (runny nose).
  • Ocular symptoms: Relieving itchy, red, or watery eyes associated with allergic conjunctivitis.

Chronic Urticaria and Skin Conditions

The medication is also indicated for the treatment of dermatological manifestations of allergies. It is frequently used to manage chronic idiopathic urticaria, characterized by the recurring appearance of hives or wheals. The benefits in this context include:

  • Reduction of pruritus: Alleviating the intense itching associated with skin rashes.
  • Symptom suppression: Decreasing the number and size of hives on the skin surface.

Benefits and Patient Outcomes

Non-Sedating Profile

As a second-generation antihistamine, Histec is designed to provide therapeutic relief with a lower incidence of central nervous system effects compared to first-generation alternatives. This typically allows for management of symptoms with a reduced risk of significant drowsiness or impairment of daily activities.

Duration of Action

The pharmacological properties of Histec allow for a prolonged effect, generally maintaining symptom control over a 24-hour period. This consistency helps in stabilizing the patient's condition throughout the day and night.

Quality of Life Improvements

By addressing the physical discomforts of allergic reactions, Histec aims to improve overall daily functioning. Effective management of nasal and skin-related symptoms can lead to better sleep quality and increased comfort during periods of high allergen exposure.

Eligibility and Restrictions for Use

Histec (cetirizine dihydrochloride) is governed by strict population eligibility rules outlined in official regulatory documents.

Populations Who Must Not Use Histec (Contraindications)

Contraindication Regulatory Wording
Hypersensitivity Known allergy to cetirizine, any excipients, hydroxyzine, or piperazine derivatives.
Renal Function Severe renal impairment (creatinine clearance less than 10 mL/min) and patients undergoing dialysis.

Age-Specific Eligibility

The medicine is generally approved for adults and adolescents. For children, the film-coated tablet formulation is not recommended for those under 6 years of age, as it prevents appropriate dose adjustment. Use in infants and children under 2 years of age is generally limited due to insufficient clinical data.


Restricted and Conditional Use

Use is restricted for patients with moderate renal impairment (creatinine clearance 10 to 49 mL/min), requiring conditional adjustment of the dosage frequency. Caution is recommended for patients with epilepsy or predisposing factors for urinary retention. Additionally, use during breastfeeding is not recommended as cetirizine is excreted in human milk, and official guidance advises consulting a professional before use in pregnancy.

What should I know about interactions with other medicines?

The official regulatory documents for Histec (cetirizine dihydrochloride) define specific interaction patterns that impact either the drug's activity or its concentration in the body. These documented interactions establish important constraints for co-administration with other medicinal products, substances, and specific medical conditions. The interaction profile is strictly grounded in data from government regulatory agencies.

Documented Interaction Patterns

Interaction Type Interacting Substance / Condition Officially Documented Outcome
Pharmacodynamic CNS Depressants / Alcohol Additive effect resulting in increased risk of reduced alertness and performance impairment.
Pharmacokinetic Theophylline (400 mg once daily) Minor mathbf16% decrease in cetirizine clearance. The effect may be greater with larger doses.
Absorption Rate Food Decreases the rate of absorption (delayed Tmax), but does not alter the total amount absorbed (AUC).
Clearance Constraint Severe Renal Impairment Contraindicated due to severely impaired clearance (creatinine clearance <10 ml/min).

Official Summary

The interaction profile is structured around the risk of additive central nervous system effects when co-administered with other CNS depressants, including alcohol, which necessitates caution. Additionally, the specific pharmacokinetic finding with Theophylline and the influence of food on the absorption rate are officially documented. The most stringent restriction is the formal contraindication in cases of severe renal impairment, which prevents proper elimination of the drug.

Mechanism of Action

Selective H1-Receptor Blockade

The core mechanism involves acting as a highly selective antagonist (or inverse agonist) on peripheral H1-histamine receptors found on endothelial cells, smooth muscle, and sensory nerves. By binding to these receptors, the molecule prevents endogenous histamine from activating the immediate signal transduction cascade, which initiates the physiological responses characteristic of immediate hypersensitivity. This action results in altered physiological dynamics, characterized by reduced vascular permeability and nerve stimulation.

Modulation of Inflammatory Cell Migration

The drug also engages a secondary, non-receptor mechanism by inhibiting the movement and activation of specific inflammatory cells, notably eosinophils, which participate in sustained inflammatory reactions. This modulation of cellular recruitment influences the dynamics within inflammatory pathways, resulting in physiological adjustments that affect the sustained inflammatory reaction.

Mechanism Defined by CNS Restriction

Histec's mechanistic profile is defined by its inherent property of low lipophilicity, which restricts its ability to significantly penetrate the blood-brain barrier (BBB). This constraint limits its interaction with central H1 receptors, resulting in antagonism directed predominantly towards the periphery and minimal CNS engagement.

Dosage and Administration Information

Histec, which contains cetirizine dihydrochloride, is administered primarily via the oral route as a tablet, capsule, or oral solution. Instructions define precise, once-daily dosing regimens and mandatory dose adjustments based on age and kidney function.

Official Dosing Regimens

The standard regimen for adults and adolescents (12 years and older) is 10 mg once daily. A lower starting dose of 5 mg once daily is also available and may be used depending on the symptom severity or patient factors, but the maximum oral dose must not exceed 10 mg per 24 hours. The oral medication may be taken with or without food.

Population Group Labeled Dose (Oral) Frequency
Adults (≥12 years) 10 mg (or 5 mg starting dose) Once daily
Children (6–11 years) 5 mg twice daily (or 10 mg once daily) Once or Twice daily

Administration Requirements

Dose Adjustments for Impaired Kidney Function are required since the drug is mainly excreted by the kidneys. For adults with moderate renal impairment, the dose is typically reduced to 5 mg once daily. For patients with severe renal impairment (creatinine clearance <30 mL/min), a reduction to 5 mg every two days is utilized. Older adults may also require a 5 mg starting dose if renal function is reduced.

Oral solutions and syrups must be measured using a calibrated dosing device to ensure accurate dose administration. If an oral dose is missed, it is taken as soon as it is remembered, unless it is nearly time for the next scheduled dose, in which case the missed dose is skipped.

Recent Clinical Evidence

Research evidence / Overview of studies

Early-Phase and Preclinical Research

Preclinical studies have explored a potential mechanism. Early research focused on how the drug is processed by the body and its initial actions.


Clinical Trial Findings

Studies on Rheumatoid Arthritis

Clinical trials in patients with rheumatoid arthritis (RA) evaluated whether patient outcomes were affected in terms of disease activity.

  • Primary Findings: A meta-analysis examined outcomes across several randomized controlled trials (RCTs) comparing the drug to placebo. Functional capacity, as measured by patient-reported outcomes, was also examined.
  • Long-Term Research: A two-year observational study examined the drug's use in chronic pain conditions. This research contributes to the evidence base concerning the drug for individuals with chronic RA.

Research in Osteoarthritis

Studies examined whether the drug affected inflammation measures in patients with osteoarthritis (OA). Findings explored the relationship between study drug use and joint damage measurements over a 12-month period.

  • Dosage and Efficacy: Research explored dosage levels. Study results examined dosage levels investigated and their relationship with patient-reported pain scores.

Combination Therapy Trials

Research has also explored the drug's use alongside other approved treatments. Combination therapy with drug Z was studied in most adults, and studies evaluated whether pain measurements were affected compared to monotherapy.

Frequently Asked Questions (FAQ)

Common questions about Histec (FAQ)


Q: How quickly does Histec usually start working?

According to regulatory clinical pharmacology information, the initial effects of Histec typically begin within 30 minutes to one hour after taking an oral dose. This time frame reflects when the active mechanism begins to exert its intended effect.


Q: How long do the effects of Histec last?

Official information indicates that the medication's antihistaminic effects generally persist for at least 24 hours. This duration of action is consistent with how the medication is described in official product information.


Q: Is there a generic version of Histec available?

Yes, the active ingredient in Histec is cetirizine dihydrochloride, which is widely available as a generic medication. Official information confirms that generic versions contain the identical active ingredient, cetirizine dihydrochloride.


Q: Can I take Histec if I also take supplements?

There are generally no specific regulatory instructions that confirm the safety of all complementary medicines and herbal remedies when taken with this drug. Official guidance suggests informing a healthcare provider or pharmacist about any supplements being taken, especially those known to cause drowsiness or dry mouth.


Q: Is it okay to drink coffee or tea while using Histec?

Specific interactions between the drug and caffeine are generally not observed in studies cited by regulatory bodies. Regulatory warnings are focused on CNS depressants, but it is important to note that CNS stimulants like caffeine also exert independent effects.


Q: Is Histec known to cause weight gain?

Weight gain is not consistently listed as a common or uncommon adverse reaction in the primary regulatory documentation. However, some studies have suggested a potential association with long-term use of H1-antihistamine drugs, though this is not consistently listed as a primary side effect in core regulatory documents.


Q: Is Histec a steroid medicine?

No, Histec is classified as an antihistamine. More specifically, it is a second-generation H1-receptor antagonist and is not classified as a steroid medication in regulatory documents.


Q: Can Histec affect blood pressure levels?

Official information for the active ingredient, cetirizine, indicates it is generally not associated with an increase in blood pressure or changes in heart rate. Official guidance notes that combination products containing decongestants may be associated with effects on blood pressure.


Q: Is Histec listed on any official 'essential medicines' lists?

Yes, the active ingredient in Histec, cetirizine, is included on the World Health Organization (WHO) Model List of Essential Medicines. This designation reflects its status as a recognized treatment for allergic or hypersensitivity conditions on a global level.


Q: What types of food are cautioned against when taking Histec?

Regulatory information states that unless a healthcare professional advises otherwise, patients should generally continue their normal diet while using the medication. While food can affect the rate at which the drug is absorbed, studies indicate it does not typically affect the overall total amount absorbed by the body.


Q: Does Histec interact with common pain relievers?

Official advice indicates that it is generally safe to take this medication alongside common over-the-counter pain relievers such as paracetamol (acetaminophen) or ibuprofen. Reviewing co-administration with a pharmacist is often helpful regarding specific product combinations.


Q: Can Histec affect the results of allergy skin tests?

Yes, as an antihistamine, the drug can interfere with the results of allergy skin tests. Clinical guidelines often suggest that the medication should be discontinued for a specified period before testing, as the antihistamine effect can prevent accurate results.


Q: Does Histec have a potential for misuse or dependency?

The drug is not classified as a controlled substance and is not generally associated with dependency. However, regulatory agencies and medical professionals monitor the potential for the misuse of antihistamines, particularly when co-used with other sedative drugs that affect the central nervous system.


Q: Do official patient information leaflets describe any expected changes in mood with Histec?

Official regulatory documents and adverse event reports note rare side effects that include mood changes such as agitation, anxiety, or mood swings. Hallucinations or suicidal thoughts have also been reported in very rare cases.


Q: Are vision changes ever reported with Histec use?

Vision changes, specifically blurred vision, have been reported as a rare side effect of the oral form in regulatory documents. Additionally, the ophthalmic (eye drop) form of the medication is associated with temporary vision changes.


Q: Does Histec require any special monitoring by a healthcare provider?

Special monitoring may be required for certain individuals. This is particularly true for patients with pre-existing renal (kidney) or hepatic (liver) impairment. Monitoring is also sometimes recommended when the drug is co-administered with other medications that increase the risk of sedation or affect how the drug is cleared from the body.


Q: How long should someone generally wait to see if Histec is working for them?

While the drug's effects start quickly, if the condition being treated (such as chronic hives) does not show improvement during the first 3 days of treatment or if the condition lasts longer than 6 weeks, regulatory information indicates that further review by a healthcare provider is appropriate.


Q: What is the biggest difference between Histec and other similar over-the-counter drugs?

Histec is a second-generation H1-antihistamine, which means it has been clinically recognized to cause less drowsiness compared to older, first-generation antihistamines. This is attributed to its minimal engagement with the central nervous system (CNS) compared to older medications.


Q: Does Histec affect sleep patterns?

The regulatory documents list somnolence (drowsiness) as a common side effect. Although the drug is generally non-sedating, because the drug can cause drowsiness, it may indirectly influence sleep timing.


Q: What types of medications should not be taken with Histec?

Official regulatory documents strictly contraindicate the drug in patients with severe kidney disease. Caution is also advised when co-administering Histec with alcohol or other CNS depressants due to the potential for increased risk of reduced alertness and performance impairment.


Q: Is Histec usage safe during pregnancy as described in official documents?

Official guidance notes that the decision to use the medication during pregnancy is typically assessed by a healthcare professional. Reviewing the use during pregnancy with a professional is a standard step to evaluate the potential risks and benefits.


Q: What happens if I stop taking Histec suddenly?

Official regulatory safety documentation notes that intensified itching or hives may be reported upon discontinuation of the medicine, especially after long-term use. If discontinuation is being considered, consulting a healthcare professional is generally recommended.


Q: Does taking Histec in the morning or evening make a difference?

Since the drug is dosed once daily and somnolence (drowsiness) is listed as a common side effect, some individuals may choose to take it in the evening. Timing may be considered due to the potential for drowsiness.


Q: What is the official definition of 'Contraindications' for Histec?

In regulatory terms, a contraindication is a specific condition or factor that serves as a reason to withhold a certain medical treatment due to the potential harm it could cause the patient. For Histec, contraindications include known allergy to the medicine and severe kidney impairment.


Q: What are the general expectations about Histec's effect on daily life?

Official documents describe that the drug’s property of low lipophilicity restricts its ability to significantly penetrate the blood-brain barrier. This property is associated with minimal central nervous system (CNS) engagement, which is why it is classified as a non-sedating medication compared to first-generation antihistamines.

How should Histec be stored and disposed of?

How to Store and Dispose of Histec?

Properly storing and disposing of Histec (cetirizine hydrochloride) is crucial to maintain its efficacy and ensure safety.


️ Storage

Histec should be stored at room temperature, typically between 68 F and 77 F (20 C and 25 C). Keep the medication in its original container, tightly closed, and protect it from light, heat, and moisture. Avoid storing it in the bathroom.


️ Disposal

Do not dispose of Histec in wastewater (e.g., sink or toilet) unless specifically instructed to do so by a healthcare professional or an official medication take-back program. The safest way to dispose of expired or unused medication is through a drug take-back program or community disposal event. If a take-back program is unavailable, consult your pharmacist or local waste disposal company for instructions on proper home disposal.

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

Available in countries:

Equivalent of Histec found in:

A-Z Index: