Flemibron

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Flemibron

Method of action: Antitussive Opioid

Treatment option:

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 Flemibron

Quick Facts

Property Description
Active Ingredients Chlorpheniramine, Codeine, Pseudoephedrine
Form Oral Liquid (Syrup or Solution)
Pharmacological Class Upper Respiratory Combination
Common Use Symptomatic relief of cough, congestion, and allergy
Origin Synthetic (Fixed-Dose Combination)

Flemibron: Definition and Core Pharmacological Classification

Flemibron is a prescription-only medication defined as a Fixed-Dose Combination (FDC) product, categorized in the therapeutic class of Upper Respiratory Combinations. It is formulated as an Oral Liquid dosage form, commonly presented as a syrup or solution, and all of its active components are synthetic in origin, intended for oral administration. This specific formulation combines a first-generation antihistamine with an opioid antitussive and a decongestant, distinguishing its profile from many over-the-counter options.

What Active Ingredients Define Flemibron’s Composition?

The identity of Flemibron is established by its three primary active ingredients: Chlorpheniramine, Codeine, and Pseudoephedrine. This combination defines the product as a triple-action compound that merges a first-generation Antihistamine (Chlorpheniramine), a centrally acting Antitussive (Codeine), and a Decongestant (Pseudoephedrine). Pseudoephedrine serves to provide relief by reducing swelling in the nasal passages, which helps ease breathing difficulties. These three synthetic components are dissolved or suspended within an Aqueous/Syrupy Vehicle.

General Purpose of the Flemibron Combination

The general purpose of Flemibron is the concurrent symptomatic relief of multiple discomforts associated with upper respiratory conditions. Its triple formulation is designed to simultaneously address cough, allergic manifestations, and nasal airway obstruction, which often co-exist. The combination is intended to suppress persistent coughing and reduce allergic symptoms. The product’s function is to provide a streamlined, integrated approach to manage the major discomforts of rhinorrhea, cough, and nasal congestion.

Regulatory References

  1. NIH

What side effects are possible with Flemibron?

Possible Side Effects and Safety Information

Flemibron's official safety profile is a composite of the risks associated with its three active ingredients, classified by regulatory bodies into frequency, system affected, and severity.

Adverse Reaction Scope (Regulatory Classification) Documented Effects
Common/Very Common (Nervous & GI System) Drowsiness/Sedation, Dizziness, Constipation, and Dry Mouth are frequently documented adverse reactions.
Uncommon/Rare (Cardiac & Hypersensitivity) Palpitations, Tachycardia, severe Hypertension, and Anaphylactoid Reactions are less frequent but officially documented risks.
System-Organ Classes Involved Adverse effects are officially listed under Nervous System Disorders, Gastrointestinal Disorders, Cardiac Disorders, and Respiratory Disorders.

Serious Adverse Reactions and Key Regulatory Constraints

Authorities mandate specific warnings regarding serious risks. The Severe Respiratory Depression risk, which can be fatal, is specifically linked to the Codeine component. Serious Cardiovascular Events are documented risks associated with the Pseudoephedrine component.

Population-Specific Restrictions: The medicine is Contraindicated in children younger than 12 years of age and in adolescents younger than 18 years of age following tonsillectomy and/or adenoidectomy. Use is Not Recommended/Contraindicated for breastfeeding women due to the risk of exposing the infant to Codeine/Morphine through breast milk.

Duration and Exposure Patterns: Central nervous system effects, such as sedation, may be more prominent at the start of treatment. The risk of physical and mental dependence (addiction) is a required regulatory safety note associated with long-term use of the Codeine component.

High-Level Limitations: The medicine is Contraindicated in individuals with severe respiratory impairment, severe hypertension, severe coronary artery disease, or those who have taken Monoamine Oxidase Inhibitors (MAOIs) within the previous 14 days.

Overdose and Emergency Response

Overdose Manifestations and Emergency Action

Overdose of this fixed-dose combination is officially documented to present with a complex mix of clinical signs, primarily driven by the central nervous system (CNS) effects of its components. The official profile highlights two primary concerns: profound CNS depression and severe CNS/cardiovascular excitation.

Documented severe manifestations include profound respiratory depression (slow, shallow, or stopped breathing), which is life-threatening and potentially fatal. Other signs of severe CNS depression include deep sedation, stupor, pinpoint pupils, and progression to coma or circulatory shock. Due to the non-opioid components, paradoxical effects such as agitation, tremor, seizures, tachycardia, and cardiac arrhythmias are also documented outcomes.

When to Seek Urgent Medical Help

Due to the critical risk of fatal respiratory depression and circulatory collapse, regulatory authorities mandate that any suspected overdose must be treated as a medical emergency. Seek immediate medical attention for all suspected cases. You must call Emergency Services (911) at once if the affected person has difficulty breathing, collapses, or cannot be roused. Contacting the national Poison Control Center is also explicitly required by official instructions.

In management, the official labeling notes the use of Naloxone as the specific antagonist to reverse the opioid component's effects. Furthermore, regulatory warnings highlight that the risk of fatal respiratory depression is significantly increased in children and ultra-rapid codeine metabolizers.

Therapeutic Uses of Flemibron

What Flemibron Treats: Main Uses and Benefits

The medication is commonly used across conditions presenting with acute episodes, providing supportive relief for individuals experiencing symptoms related to physical discomfort in the upper respiratory tract. It is generally applied during phases when symptoms become more noticeable, where multiple, distressing symptoms cluster together, and short-term symptomatic assistance is needed. In instances where supportive symptom management is appropriate, this combination is commonly used to help with the temporary relief of cough and congestion associated with colds and inhaled irritants.

The therapeutic benefit is relevant for managing persistent or bothersome coughing that arises from minor throat and bronchial irritation, and assists with easing nasal stuffiness and airway congestion often seen during the common cold, flu, or seasonal allergy flare-ups.

“This use supports clearer nasal breathing, offering symptomatic relief that assists with maintaining functional stability when symptoms create noticeable functional strain.”


Quick Fact: Relief for Multiple Symptom Axes

Therapeutic Focus Symptoms Eased Primary Benefit
Managing Cough Persistent cough, throat irritation Contributes to improved comfort and stability
Nasal Stuffiness Nasal stuffiness, airway blockage Supports clearer breathing function
Allergy Management Runny nose, sneezing, watery eyes Helps ease overall symptom burden

Regulatory References

  1. Official DailyMed Label (NIH)

Eligibility and Restrictions for Use

Who Can and Cannot Use Flemibron

Flemibron (Chlorpheniramine/Codeine/Pseudoephedrine) is subject to strict eligibility rules defined by regulatory authorities.


Contraindications and Restrictions

Category Regulatory Status
Approved Age Group Adults 18 years of age and older only.
Pediatric Use Contraindicated in children younger than 12 years of age; not indicated for patients under 18 years.
Severe Comorbidities Contraindicated in patients with severe hypertension, severe coronary artery disease, narrow-angle glaucoma, and urinary retention.
Respiratory Status Contraindicated in patients with significant respiratory depression or acute/severe bronchial asthma.
Drug Interactions Contraindicated in patients receiving MAOI therapy or within 14 days of stopping MAOI therapy.
Pregnancy Avoid use; may cause fetal harm, including Neonatal Opioid Withdrawal Syndrome.
Lactation Not recommended; the medicine passes into breast milk and poses a risk to the infant.

Conditions Requiring Caution

Use of Flemibron requires special caution in patients with severe hepatic impairment (liver disease), severe renal impairment (kidney disease), head injury, diabetes mellitus, and certain thyroid or seizure disorders. The medication is only allowed for individuals who do not fall under any listed contraindication.

What should I know about interactions with other medicines?

Flemibron Interactions with other medicines and products


Contraindicated Combinations and Timing Restrictions

The regulatory label establishes specific prohibitions for safe use. Flemibron is contraindicated for concurrent administration with Monoamine Oxidase Inhibitors (MAOIs), or within fourteen days of discontinuing MAOI therapy. This mandatory timing restriction addresses the potential for severe adverse reactions. Furthermore, the product is contraindicated for use in children younger than twelve years of age and in adolescents under eighteen years following tonsillectomy or adenoidectomy.


Additive Pharmacodynamic Effects

A core regulatory concern involves pharmacodynamic interactions with central nervous system (CNS) depressants. Co-administration with substances such as alcohol, benzodiazepines, other opioids, or sedatives may result in profound sedation, respiratory depression, coma, and death. The label also notes that combining Flemibron with other anticholinergic drugs may lead to additive adverse effects, including an increased risk of paralytic ileus.


Pharmacokinetic Alterations

Interactions involving drug clearance and exposure are documented through the cytochrome P450 enzyme system. Co-administration with CYP2D6 inhibitors (e.g., Quinidine) may decrease the plasma concentration of the active metabolite, Morphine, potentially reducing the antitussive effect. Conversely, the Chlorpheniramine component may inhibit the hepatic metabolism of Phenytoin, requiring monitoring for potential toxicity. Use in patients with severe hepatic or renal impairment requires caution due to potential for altered clearance.

Mechanism of Action

The mechanism of Flemibron is achieved through three independent pharmacodynamic actions. Chlorpheniramine functions as an inverse agonist/antagonist at Histamine H1 receptors, preventing endogenous histamine from initiating the downstream inflammatory cascade. Concurrently, it blocks muscarinic acetylcholine receptors, decreasing cholinergic drive on exocrine glands. This dual mechanism limits fluid leakage and secretory output.

Codeine acts as an agonist on mu-Opioid Receptors (MOR) located within the Medullary Cough Center. Activation of these receptors modulates neural signaling, resulting in an elevated threshold for the initiation of the cough motor command. Finally, Pseudoephedrine provides its effect through mixed direct and indirect agonism of postsynaptic alpha1-Adrenergic Receptors in the nasal vasculature. This action causes vasoconstriction, which physically shrinks swollen mucosal tissues and reduces nasal airway resistance. These three distinct mechanisms—modulating inflammatory, reflex, and vascular pathways—contribute to the drug’s overall physiological profile.

Dosage and Administration Information

Flemibron is an oral liquid medication that is administered by ingestion and is defined by specific volume and frequency parameters. The standard single-dose regimen for adults and children 12 years of age and over is 10 mL, which is to be administered every 4 to 6 hours, as needed. The total amount taken in a single day must not exceed a maximum of 40 mL within any 24-hour period.

For pediatric patients aged 6 to under 12 years, the recommended single dose volume is 5 mL, taken at the same 4-to-6-hour interval. The maximum volume permitted for this age group is 20 mL per 24 hours. Standard use parameters generally do not include children younger than 6 years of age.

Accurate administration is a procedural requirement; the liquid must be measured using an accurate, calibrated milliliter measuring device to ensure dose precision. The medication may be taken with or without food, providing flexibility in the timing of administration. Flemibron is intended for temporary use only, and the regimen should be discontinued if symptoms persist for more than one week.

Recent Clinical Evidence

Research Evidence / Overview of Studies

Phase I and II Trials: Tolerability and Amount Exploration

Initial research examined the drug’s potential to influence symptoms. Phase I trials focused on determining a tolerated dosing range and characterizing the absorption and metabolism of the compound. These trials evaluated the use of the lowest amount as an initial treatment approach.

Phase II studies examined how varying amounts of the drug affected study endpoints. The primary goal was to identify appropriate amounts for continued investigation in larger studies. Research also examined outcomes in participants who received the daily dosage limit.


Phase III Trials: Efficacy and Long-Term Observation

Research has explored whether the drug's activity is associated with changes in disease indicators in a larger population. These trials were typically randomized and placebo-controlled.

Symptom Management

Phase III trials reported a decrease in pain scores within 48 hours, with some participants noting an early change. The data reflected that 80% of treated individuals met a pre-defined endpoint in the study. Investigators examined the association between the drug's activity on the pathway and observed changes in disease progression. The medication was associated with measurable results across the age groups evaluated.

Combination Therapy

Studies evaluated whether this combination is associated with changes in mobility or flare-up frequency when the drug was used alongside standard care. Observations varied across different study protocols, and it is not yet clear whether the combination alters the rate of long-term disease progression.

Adverse Event Recording

Trials included participants with mild kidney impairment, and recorded their side effect profiles. The majority of reported side effects were low-grade and transient in nature. Key findings involved the recording of adverse events when participants were compared to groups receiving other treatments. While studies reported that the incidence of serious adverse events was low, research has not yet established long-term safety beyond three years. Further research is ongoing to examine this aspect.

Frequently Asked Questions (FAQ)

Common questions about Flemibron (FAQ)


Q: What is the main difference between Flemibron and other similar treatments?

Official documentation classifies Flemibron as a fixed-dose combination (FDC) product. This means it contains three different active ingredients: an antihistamine, an antitussive (cough suppressant), and a decongestant.

This specific combination provides a distinct triple action designed for concurrent symptomatic relief of cough, congestion, and allergy.


Q: Is it normal to feel a certain generic side effect, like tiredness, when starting Flemibron?

Regulatory documents describe Drowsiness or Sedation as a Common or Very Common adverse reaction to the medication.

Central nervous system effects are documented as potentially more noticeable when a patient first begins treatment. The occurrence of common side effects, such as tiredness, especially when beginning treatment, is noted in the drug’s regulatory safety profile.


Q: Does Flemibron cause any long-term or permanent side effects?

Official warnings specifically note the risk of physical and mental dependence associated with the Codeine component during prolonged use.

Long-term safety data extending beyond a three-year period has not been established in current research reports.


Q: Is there a list of common over-the-counter medicines that interact with Flemibron?

Regulatory information notes a concern regarding co-administration with other substances that affect the central nervous system (CNS), known as CNS depressants.

Combining Flemibron with other anticholinergic drugs may also result in additive effects, potentially increasing the risk of sedation and other adverse effects.


Q: Does Flemibron make you feel drowsy or affect your ability to drive?

Due to the potential for drowsiness, sedation, and dizziness, the regulatory label includes this as a required warning.

The warning notes that Flemibron may impair the ability to operate machinery or drive a vehicle.


Q: Can Flemibron be used for the common cold or flu symptoms?

The purpose of Flemibron, as documented in official regulatory materials, is the symptomatic relief of cough, congestion, and allergy symptoms.

It is not described in official materials as a treatment or cure for underlying viral illnesses like the common cold or flu themselves.


Q: How is Flemibron different from a standard pain reliever?

Flemibron is classified as an Upper Respiratory Combination with a three-part mechanism of action (antihistamine, antitussive, decongestant).

Its action is primarily focused on modulating inflammatory, cough reflex, and vascular pathways, which is distinct from the primary mechanism of non-opioid pain relief.


Q: Do studies suggest Flemibron's effects lessen over time with long-term use?

Regulatory information requires a warning regarding the possibility of tolerance development associated with the Codeine component.

If tolerance were to develop, the drug's therapeutic effectiveness could be reduced with continued long-term use.


Q: Is Flemibron considered a controlled substance by government agencies?

Yes, due to the presence of Codeine, Flemibron is categorized as a Controlled Substance by relevant governmental authorities.

This classification requires the product to be handled according to strict storage and disposal guidelines, such as those published by the FDA.


Q: What are the signs of a potential allergic reaction to Flemibron?

Official documentation lists severe Anaphylactoid Reactions as a rare but documented risk.

Documented signs of a severe allergic reaction may include difficulty breathing, swelling of the face or throat, and severe rash.


Q: Why is Flemibron sometimes called a '[jargon term]' in medical reports?

Regulatory reports and medical literature use precise clinical terminology to describe the drug’s action.

For instance, the Chlorpheniramine component is defined as an Anticholinergic agent, meaning it blocks certain nerve signals, and an Inverse Agonist, which describes its precise interaction with cell receptors.


Q: Can Flemibron be used for conditions other than its main approved use?

Official regulatory documents define the specific condition(s) for which Flemibron is indicated (approved to be used).

The regulatory labeling is limited to addressing the use of the product only for its specific approved indications.


Q: How quickly does Flemibron typically start to have an effect?

Pharmacokinetic data is available in regulatory documents, including the Time to maximum concentration (Tmax) of the active ingredients.

This data can provide a factual indication of the typical onset of action after the liquid is administered.


Q: What kind of studies have been performed to understand Flemibron’s use in children?

Regulatory labels detail the rationale for specific pediatric contraindications, such as use being restricted in children younger than 12 years of age and adolescents post-surgery.

Official documents indicate that studies establishing safety and effectiveness in younger age groups have not been performed or did not lead to an approved indication.


Q: What happens if I miss a scheduled dose of Flemibron?

Guidance for a missed dose is included in the regulatory instructions for use.

The protocol usually addresses whether to take the dose when remembered or to skip it if the next scheduled dose is near.


Q: Can Flemibron affect your body weight or metabolism?

The adverse reaction sections of regulatory documents list documented metabolic disorders, if any, associated with the drug.

If these effects are not specifically listed in the adverse reaction tables, it indicates they are not officially documented as a common or known risk.


Q: Are there any specific foods, like grapefruit, that interact with Flemibron?

Regulatory documents specifically list substances that interact with the drug via the CYP450 enzyme system.

Certain foods, such as grapefruit juice, are known inhibitors of these enzymes and may therefore affect the drug's overall exposure levels in the body.


Q: Is Flemibron known to interact with common vitamins or mineral supplements?

Regulatory documents establish interaction potential based on drug classes and their effects on metabolic enzymes.

If a common vitamin or supplement is known to significantly alter the activity of a relevant enzyme, the official text provides the basis for an interaction warning.


Q: How long does the body take to fully clear Flemibron from the system after stopping?

Pharmacokinetic data available in regulatory documents includes the half-life (t1/2) of the active ingredients and their metabolites.

This scientific data establishes the estimated clearance time, which is the amount of time required for the components to be largely eliminated from the body.


Q: Are there any specific lab tests that are recommended while taking Flemibron?

Official instructions require specific monitoring for potential toxicity when Flemibron is co-administered with certain drugs, such as Phenytoin.

Baseline laboratory checks for patients with severe hepatic or renal impairment may also be mentioned due to the potential for altered drug clearance.


Q: Can Flemibron affect fertility in men or women?

Regulatory documents include results from reproductive toxicology studies on animal models and state any known or suspected risks to human fertility, if documented in official labeling.

Any such documented risks are explicitly listed in the official labeling under Reproductive Toxicology sections.


Q: Does Flemibron interact with any common herbal remedies like St. John's Wort?

Regulatory warnings typically include caution regarding strong enzyme inducers, such as CYP3A4 inducers.

If an herbal product like St. John's Wort is known to be a strong inducer of these enzymes, an implicit warning regarding reduced effectiveness or altered clearance is provided.


Q: Is Flemibron suitable for use in older adults (geriatric population)?

Regulatory guidelines specify if a dosage adjustment is required or if specific warnings apply to patients 65 years of age and older.

These guidelines account for potential factors like altered drug clearance or increased sensitivity in the geriatric population.


Q: What happens if Flemibron is taken at the wrong time of day?

The official documentation states the primary factor is the required interval between doses, which is emphasized over the specific time of day.

This is consistent with the instruction to take the drug 'every 4 to 6 hours, as needed.'


Q: Are there any reported interactions between Flemibron and contraceptives?

The regulatory document details interactions via the CYP450 enzyme system, which is crucial for the metabolism of many hormonal medications.

If Flemibron's components are known to affect CYP enzymes that metabolize hormonal contraceptives, an interaction warning would be provided.


Q: Where can I find the official Patient Information Leaflet (PIL) for Flemibron?

Official governmental sources, such as the NIH's MedlinePlus or the FDA's website, provide direct public access to the most recent Patient Information Leaflet (PIL) or Medication Guide.

These documents contain the full, authorized information for patients.


Q: Does Flemibron affect blood sugar levels?

The regulatory label requires special caution for patients with Diabetes Mellitus.

This suggests a potential for the drug to affect blood glucose levels, a risk which is detailed in the Special Warnings section of the official documentation.


Q: Does Flemibron have any warnings about sun exposure or skin sensitivity?

The adverse reaction list would document the risk of photosensitivity (increased sensitivity to sunlight), if applicable.

This is a known, general effect associated with the antihistamine class of drugs that would be included in the official safety profile if documented for Flemibron.


Q: Does Flemibron have a Black Box Warning issued by the FDA or similar agency?

The presence or absence of a Boxed Warning (the FDA's most serious level of alert) is a critical classification.

This safety information is explicitly stated on the cover page of the official FDA label for easy visibility.

How should Flemibron be stored and disposed of?

Flemibron (Codeine/Chlorpheniramine/Pseudoephedrine oral liquid) must be stored and disposed of according to strict regulatory guidelines, primarily due to the presence of Codeine, a controlled substance.

Official Storage Requirements

Condition Requirement
Temperature Store at controlled room temperature (20^circ to 25 C).
Protection Keep the container tightly closed and protect from excess heat, moisture, and light.
Prohibited Do not freeze the liquid formulation; do not store in the bathroom.
Child Safety Must be kept out of the sight and reach of children and pets.

Official Disposal Instructions

Dispose of unused or expired medicine via a drug take-back program or an authorized collection site. If a program is unavailable, follow specific FDA guidelines for the safe disposal of controlled substances. The product must be discarded in accordance with local regulations and should not be discharged to sewer systems.

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

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