Surdex

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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 Surdex

Quick Facts

Property Description
Active Ingredients Chlorpheniramine, Paracetamol, Phenylephrine
Form Oral Tablet, Oral Liquid (Syrup/Suspension)
Pharmacological Class Multi-component Symptomatic Cold/Allergy Agent
General Purpose Relief of multiple cold and allergy symptoms
Origin Synthetic Compounds

What Type of Medicine is Surdex?

Surdex is classified as a synthetic, multi-component fixed-dose combination (FDC) medicine intended for the oral route of administration. This preparation is strategically formulated by uniting three distinct active ingredients into established pharmaceutical preparations, available as both tablets and oral liquid forms, such as syrups or suspensions. Its classification as an FDC means the components are delivered together in a fixed ratio, offering a unified approach to managing complex symptom patterns. Scientific reviews generally indicate the efficacy of such cold and allergy FDC products in providing relief for acute upper respiratory symptoms. The multi-action feature of FDCs is recognized for its efficiency in addressing the simultaneous nature of cold symptoms.


The Composition of Surdex: Key Active Ingredients

The high-level composition of Surdex is based on three active ingredients: Chlorpheniramine Maleate, Paracetamol (Acetaminophen), and Phenylephrine Hydrochloride. Each ingredient belongs to a dedicated pharmacological class: Chlorpheniramine is an antihistamine, Paracetamol acts as an analgesic and antipyretic, and Phenylephrine functions as a sympathomimetic nasal decongestant. The use of Phenylephrine as a nasal decongestant is established for its role in reducing swelling in the nasal passages. This confirms that the formula contains a component specifically designed to help clear nasal obstruction. Formulations with this specific triad of components, such as Surdex, are often targeted towards adults and children, differentiating them from single-ingredient formulations.


Surdex: General Therapeutic Purpose

The overall goal of Surdex is to provide integrated symptomatic comfort by leveraging the combined effects of its components. By simultaneously addressing three key mechanisms—allergic response, pain/fever, and nasal congestion—the medicine serves the general therapeutic purpose of alleviating the multiple discomforts associated with the common cold and upper respiratory allergies, helping to restore the patient's symptomatic well-being. A typical use scenario involves the temporary relief of a stuffy nose and headache accompanying a cold.

Regulatory References

  1. NIH, 2023 Study on Cold FDCs

What side effects are possible with Surdex?

Possible Side Effects and Safety Information

The safety profile for Surdex, a multi-component formulation (Chlorpheniramine, Paracetamol, Phenylephrine), is derived from the established regulatory data of its active ingredients. Adverse reactions are classified according to frequency and the specific body system affected, consistent with official regulatory labeling.

Frequency-Classified Adverse Reactions

The most frequent effects are generally related to the antihistamine component. Drowsiness (somnolence) and sedation are officially classified as Very Common. Effects listed as Common include dizziness, dry mouth, blurred vision, and disturbances in attention.

System-Organ-Class Groupings

Adverse effects are documented across several physiological systems. Common effects are often reported in Nervous System Disorders and Gastrointestinal Disorders. Effects involving the Cardiovascular System (e.g., tachycardia, palpitations) are associated with the decongestant component, while the Skin and Subcutaneous Tissue Disorders and Immune System list reactions such as rash and severe allergic reactions.

Serious Adverse Reactions

Official regulatory documents emphasize the potential for severe reactions, including Severe Hepatic Injury/Necrosis, primarily linked to the Paracetamol component, and Severe Skin Reactions (e.g., blistering). The label also notes the risk of Anaphylaxis and potential for Hypertensive Crisis associated with the decongestant component.

Population-Specific and Contextual Safety

Safety constraints are noted for specific populations. Children may paradoxically experience excitability or restlessness. Older adults may have increased susceptibility to neurological effects like confusion. Caution is required for patients with pre-existing conditions such as liver disease (hepatic impairment), high blood pressure, and certain cardiovascular conditions, as stated in regulatory prescribing information. The official label also notes that sedation may be exacerbated by co-administration with alcohol or other sedatives.

Overdose and Emergency Response

The officially documented overdose profile for Surdex is characterized by the potential for delayed, life-threatening complications requiring immediate emergency action.

Required Emergency Action

Regulators emphasize that prompt medical help or contact with a Poison Control Center must be sought right away, even if the individual appears asymptomatic. Immediate medical attention is deemed critical for both adults and children.

Documented Overdose Manifestations

Initial signs of overdose are often mild, typically including nausea, vomiting, abdominal pain, and loss of appetite, which can mask the progression toward severe outcomes. Acute manifestations may also involve severe neurological effects such as confusion, seizures, and eventually coma, alongside dangerous cardiovascular signs like severe hypertension and uneven heart rate.

Severe Outcomes and Management

The most critical regulatory concern is the risk of severe liver damage or liver failure, which is documented to be potentially fatal. Specific risk populations, such as those with pre-existing liver disease or individuals consuming three or more alcoholic drinks daily, are noted to have an increased risk of these severe outcomes.

Hospital-based management protocols, as described in official documents, include specialized interventions such as the timely administration of the specific antidote, N-acetylcysteine, and continuous monitoring. Laboratory monitoring of serum acetaminophen levels and liver function tests is required to guide treatment.

Therapeutic Uses of Surdex

What Surdex Treats: Main Uses and Benefits

Surdex is a multi-component formulation relevant for symptomatic relief in situations involving certain distressing symptoms commonly associated with upper respiratory and allergic conditions. The antihistamine component included is associated with therapeutic domains involving multiple simultaneous symptoms.

This medication is commonly used across conditions presenting with acute episodes, such as the common cold, flu syndrome, and seasonal allergic rhinitis. It helps address symptom clusters that may become intense or disruptive, including headache, minor body aches, elevated temperature (fever), nasal stuffiness, sneezing, and runny nose.

It is relevant for easing symptoms related to inflammatory or irritative states, assisting with maintaining functional stability.

Surdex is applied in scenarios where additional management of symptoms related to systemic imbalance is appropriate, offering supportive relief that generally helps patients cope more steadily with difficult episodes and assists with maintaining functional stability.


Quick Fact Relief for Symptom
Systemic Axis Fever and generalized aches/pain
Nasal/Sinus Symptoms related to nasal congestion and pressure
Allergic Sneezing, itching, and rhinorrhea (runny nose)

Regulatory References

  1. NIH MedlinePlus overview

Eligibility and Restrictions for Use

Who Can and Cannot Use Surdex?

The official regulatory profile for Surdex is structured by specific population restrictions and absolute prohibitions. Use of Surdex is established for Adults and Children 12 Years of Age and Over.

The medicine is Contraindicated and must not be used by patients with a known Hypersensitivity to any ingredient, or those currently taking a Monoamine Oxidase Inhibitor (MAOI) or within 14 days of discontinuing MAOI therapy. Absolute prohibitions also apply to patients with Severe Hypertension, most forms of Severe Cardiovascular Disease, Severe Liver Disease, Closed-Angle Glaucoma, or Hyperthyroidism.

For Children, use is generally Not Recommended under the age of 12 for the full formulation, with some authorities restricting the combination in children under four years. The product is also Not Recommended during Pregnancy or Lactation. Specific medical conditions, including non-severe Renal or Hepatic Impairment, Diabetes Mellitus, and Epilepsy, require the medicine be used with Caution. Patients must not concurrently use Surdex with any other product containing Paracetamol.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Formal Prohibitions and Contraindicated Combinations

The regulatory profile mandates strict avoidance of certain substances. Co-administration with Monoamine Oxidase Inhibitors (MAOIs) is formally contraindicated due to the severe risk of potentiating the pressor effects of Phenylephrine, which can lead to hypertensive crisis. Use with other paracetamol-containing products is also strictly prohibited to prevent exceeding the recommended total daily dose, mitigating the associated risk of severe hepatotoxicity. Furthermore, combining Surdex with other sympathomimetics is restricted due to the cumulative risk of cardiovascular side effects, including hypertension and arrhythmias.

Pharmacodynamic and Exposure-Altering Interactions

The Chlorpheniramine component, an antihistamine, introduces significant pharmacodynamic constraints. Concurrent use with Central Nervous System (CNS) Depressants (e.g., opioid analgesics, sedatives) may cause additive CNS depression and enhanced sedation. Similarly, co-administration with anticholinergic drugs can lead to a potentiation of effects such as urinary retention. Separately, Chlorpheniramine inhibits the hepatic metabolism of Phenytoin, potentially increasing its plasma concentration and risk of toxicity. Phenylephrine may reduce the efficacy of antihypertensives and increase the risk of hypertension.

Alcohol and Metabolic Restrictions

Consumption of alcohol is strongly restricted. Chronic daily consumption of three or more alcoholic drinks is associated with a heightened risk of severe liver damage when combined with the Paracetamol component. This metabolic restriction is particularly relevant for patients with pre-existing hepatic impairment or chronic alcoholism. Additionally, excessive intake of caffeine should be avoided due to the potential for additive sympathomimetic effects from the decongestant component.

Mechanism of Action

️ How Surdex Works: The Mechanism of Action

Surdex operates by engaging three distinct pharmacological mechanisms that are complementary and additive, targeting separate biological pathways to modulate specific physiological pathways.


Histamine Receptor and Mediator Blockade

The mechanism of Chlorpheniramine involves competitive antagonism at the Histamine H1 receptors. This action suppresses the binding of the inflammatory mediator histamine, which limits the resulting signaling cascade. This mechanism results in stabilization of capillary permeability and decreases neurological stimulation of sensory nerves, influencing local tissue fluid dynamics and sensory neuron firing.


️ Central Enzyme Inhibition for Temperature and Pain

Paracetamol exerts its effect by acting primarily within the Central Nervous System ( CNS) to inhibit Cyclooxygenase ( COX) enzymes, thereby reducing the synthesis of key prostaglandins like PGE2. This modulation causes the resetting of the hypothalamic temperature set point and results in elevation of the central pain threshold, modulating central nociceptive signaling pathways.


Local Vascular Smooth Muscle Modulation

The decongestant mechanism utilizes Phenylephrine's direct agonism on postsynaptic alpha1-adrenergic receptors found on the blood vessels of the nasal mucosa. This activation induces vasoconstriction, or the physical contraction of the arteriolar smooth muscle. The resulting physiological change is a reduction in local blood volume and tissue congestion, resulting in physiological reduction of local tissue volume.

Dosage and Administration Information

The medicine Surdex is indicated for oral administration, supplied in two forms: a solid tablet and an oral liquid (syrup or suspension). The standard dose for adults and children 12 years and older is typically one or two tablets per dose, which delivers Paracetamol 325 mg, Chlorpheniramine 2 mg, and Phenylephrine 5 mg in a fixed combination.

This dosage agent is intended for use on an as-needed basis, and administration must be separated by a minimum interval of four hours. The maximum intake is limited to eight tablets over a 24-hour period. Tablets are to be swallowed whole rather than crushed or dissolved. Liquid formulations require shaking before measurement to ensure dose accuracy. Surdex may be taken with or without food.

A critical constraint in the administration protocol is the prohibition against concurrent use with any other medicine containing Paracetamol (acetaminophen). The overall duration of use is restricted to short-term administration, and continued treatment beyond three to seven days requires professional consultation. Use in children under 12 years of age is governed by specific medical direction.

Recent Clinical Evidence

Surdex: Recent Clinical Evidence

Evidence for Use in Common Cold, Flu Syndrome, and Acute Upper Respiratory Symptoms

Research has examined the use of fixed-dose combination (FDC) medicines, like Surdex, in conditions characterized by fluctuating or episodic manifestations such as the common cold and flu syndrome. Studies in this area are often comprehensive reviews that look at data across multiple trials. These studies were applied in research contexts involving fluctuating or unstable symptoms to explore short-term changes.

The research explored outcomes related to physical discomfort, including measurements of how symptoms like headache, minor body aches, elevated temperature (fever), nasal stuffiness, and runny nose evolved in the observed populations. Findings describe patterns observed in these studies, where measurements of symptom change and indicators of daily function were reported over defined time intervals. Research has contributed to the evidence base on acute upper respiratory symptoms by showing that this category of FDC products has been studied for acute upper respiratory symptoms.

Evidence for Use in Seasonal Allergic Rhinitis

The component combination was evaluated in studies relevant to allergic rhinitis, a condition involving periods of heightened symptoms. These studies research examined how the antihistamine and decongestant components were evaluated together in this specific context. Researchers tracked patient-reported outcomes describing perceived discomfort related to sneezing and rhinorrhea (runny nose).

Studies in Specific Populations (Adults and Children)

Research was studied for use in formulations containing this specific triad of components across different age groups. Data show patterns related to the study of these types of FDC products in both adults and children. This information helps describe how patients reported their experience within the observed populations.

Duration of Study and Follow-up

The evidence base primarily was observed in research exploring short-term symptom changes. The available studies research examined outcomes describing episodic or acute changes in symptoms related to common cold and flu episodes. Due to the nature of the conditions being studied, follow-up durations were limited and centered on the acute phase of symptoms.

What is Still Uncertain About the Research for Surdex

While research has contributed to understanding symptom patterns for this FDC category, certain aspects remain uncertain. The evidence primarily focuses on the general FDC category and the known actions of the individual active ingredients, rather than extensive, long-term research on one specific formulation. Long-term effects are not fully established, and data for certain groups remain insufficient, meaning that research does not determine whether an individual in a less-studied population will respond similarly to the group patterns observed.

Key Studies & References Chlorpheniramine Oral (MedlinePlus Drug Information)

Frequently Asked Questions (FAQ)

Common questions about Surdex (FAQ)


Q: What kind of foods or drinks should people be aware of when taking Surdex?

Official documents state that Surdex may be taken with or without food.

However, regulatory information advises avoiding or strictly limiting the use of alcohol and excessive intake of caffeine. This is due to the potential for an increased risk of side effects or enhanced effects from the drug's components.


Q: Is Surdex known to interact with common pain relievers like ibuprofen?

Official regulatory text mandates strict avoidance of all other medicines containing Paracetamol (Acetaminophen), which is one of the active components of Surdex.

Caution is generally advised when combining Surdex with other specific analgesics, such as Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) like ibuprofen. Users should consult the Interactions section for specific guidance regarding co-administration.


Q: Is Surdex suitable for older adults (seniors)?

Use of Surdex in older adults is generally permitted but requires caution. Regulatory documents indicate that this population may have an increased susceptibility to certain central nervous system effects, such as dizziness or confusion.

This is a standard precaution noted in official guidance for the use of this type of medicine.


Q: Is Surdex safe to use if I have high blood pressure?

According to the official product information, Surdex is prohibited (contraindicated) for use in patients with severe hypertension (very high blood pressure). This is due to the decongestant component.

For non-severe high blood pressure, regulatory guidance indicates that the medicine must be used with caution.


Q: What are the official sources for information about Surdex?

Official information about Surdex is published by national regulatory authorities, such as the U.S. FDA, the European Medicines Agency (EMA), and Health Canada.

This information is typically found in the official drug labeling, such as the Summary of Product Characteristics (SmPC).


Q: Does Surdex cause any changes to your skin or hair?

Adverse reaction reports documented in regulatory files include Skin and Subcutaneous Tissue Disorders, and they specifically note the potential for severe skin reactions.

Changes specifically related to hair are not included in the core regulatory summary of adverse effects.


Q: Why is Surdex not recommended for people who are pregnant or breastfeeding?

Regulatory documents advise against the use of Surdex during both pregnancy and lactation (breastfeeding).

This is based on the potential for risk to the fetus and the possible excretion of the drug's active components into breast milk.


Q: Is Surdex the same kind of medicine as [similar drug]? What's the difference?

Surdex is classified as a Fixed-Dose Combination (FDC) medicine. This means it contains three distinct active ingredients: an analgesic (pain/fever reliever), an antihistamine, and a decongestant.

This multi-component formulation gives it a specific profile, which differentiates it from medicines that contain only a single ingredient for symptom relief.


Q: How long does it usually take to feel the effects of Surdex?

Studies indicate that the decongestant and analgesic components of this combination medicine typically begin to show measurable effects within 30 minutes to one hour following oral administration.

This information is derived from the official pharmacokinetic studies, which track how the body processes the drug.


Q: Do I need a special blood test before starting Surdex?

The general administration instructions do not list a mandatory pre-treatment blood test for all users.

However, regulatory documents advise caution for patients with pre-existing conditions, particularly liver or kidney impairment. These conditions are noted by regulators as requiring specific consideration.


Q: I've heard people talk about 'Surdex rebound'—what does that mean?

'Rebound congestion' is a recognized potential effect associated with the decongestant component (Phenylephrine).

This refers to the recurrence or worsening of nasal congestion after the medication is stopped, particularly if it was used for a prolonged period.


Q: Does Surdex affect birth control pills or other hormonal medications?

Interactions with hormonal medications, including oral contraceptives (birth control pills), are listed in the drug's regulatory profile.

Regulatory documents indicate that use may require caution or specific monitoring by a healthcare provider.


Q: What happens if I miss taking Surdex one day?

Official patient information often advises patients to maintain their schedule by taking the next dose as normal and avoiding taking a double dose to compensate for the missed one.

This ensures the maximum daily dosage limit is not exceeded.


Q: Are there any religious or cultural restrictions on using ingredients in Surdex?

The regulatory documents for Surdex include a complete list of all active and inactive ingredients (excipients).

The official list of excipients may be used to verify the absence of ingredients restricted by personal religious or cultural rules.


Q: Does Surdex contain any common allergens like gluten or lactose?

The regulatory documents include a full list of inactive ingredients (excipients) used in the formulation.

This list specifically identifies if known common allergens, such as lactose or gluten, are present in the tablets or liquid.


Q: How quickly does Surdex leave the body after you stop taking it?

The rate at which Surdex is eliminated from the body is determined by the half-lives of its individual components.

The half-lives are specified in the official pharmacokinetics section of the regulatory label.


Q: Is it normal to have mild headaches when first starting Surdex?

The official side effect profile lists frequent or common adverse reactions to the medicine.

If a mild headache occurs and is not listed as a common side effect, it is important to check the full side effect profile for guidance.


Q: Can you take Surdex with vitamin supplements?

While specific vitamin supplements may not be explicitly detailed in the interactions section, the regulatory documents advise caution with all co-administered products.

This is especially relevant for products that may affect liver function or increase central nervous system sedation.


Q: Is Surdex available over-the-counter in some countries?

The availability of Surdex is determined by the classification set by national regulatory bodies in different regions.

This classification specifies whether the medicine is considered a Prescription-Only Medicine (POM) or an Over-the-Counter (OTC) product, and this status varies by country.


Q: What is the significance of the number of studies mentioned in the research section for Surdex?

The clinical data section in official regulatory documents summarizes the key evidence used for product approval.

This summary indicates the studies that the regulators deemed sufficient to establish the drug’s efficacy and safety profile for its approved uses.


Q: What kind of health professionals are authorized to prescribe Surdex?

The authorization for prescribing or supplying Surdex is based on its regulatory classification.

If the drug is a Prescription-Only Medicine (POM), the type of professional authorized to prescribe or supply it is legally defined by the national authority.


Q: Does Surdex cause weight gain or weight loss?

The full adverse event profile is reviewed by regulators before approval.

Any clinically significant or frequently reported changes in body weight would be noted in the official label's side effect list.


Q: What is the difference between the brand name and the generic version of Surdex?

Regulatory authorities approve a generic version after it has demonstrated bioequivalence to the brand-name product.

This means the generic must contain the same active ingredients in the same dosage form and strength, and function identically to the brand-name medicine.


Q: Is Surdex addictive or habit-forming?

Regulatory bodies assess a medicine's potential for abuse and dependence.

The official label specifies if the medicine is classified as a controlled substance or notes any dependence risk associated with its active components.


Q: Is Surdex considered a 'high-risk' medicine?

Regulatory documents do not typically use terms like 'high-risk' in general classification.

However, the level of risk identified by regulators is defined by the severity of the associated warnings, contraindications (prohibitions), and the potential for serious adverse reactions, such as severe liver injury.


Q: Why do some people need to adjust the dose of Surdex over time?

The regulatory label specifies certain patient populations or pre-existing conditions that may require dosage adjustment from the standard regimen.

This is typically necessary for those with severe hepatic (liver) or renal (kidney) impairment or for elderly patients, to maintain safety and efficacy.


Q: Is there a link between Surdex and changes in mood?

The official adverse event profile for Surdex lists psychiatric and central nervous system disorders.

Reported effects include confusion, excitability, or nervousness, which cover mood-related changes.


Q: Does Surdex interact with herbal remedies like St. John's Wort?

Interactions with commonly used herbal supplements, such as St. John's Wort, which are known to interfere with drug metabolism, are routinely documented.

This information is detailed in the interactions section of the regulatory label.


Q: Is it true that Surdex needs to be stopped gradually?

The regulatory text specifies if a medicine requires tapering (gradual cessation) or if it can be stopped abruptly.

This specific instruction is found in the Administration or Warnings sections of the official document.


Q: Can Surdex affect the results of other medical tests?

Regulatory labels detail known interferences with common laboratory tests caused by the drug's active ingredients.

These interferences may affect the results of diagnostic tests, such as certain drug screening or thyroid function tests.


Q: What is the half-life of Surdex, according to pharmacokinetics studies?

The half-life of each active component is a standard pharmacokinetic parameter included in the product's regulatory data section.

This value represents the time required for the amount of the drug in the body to be reduced by half.

How should Surdex be stored and disposed of?

Storage Conditions and Environment

Surdex must be stored at Controlled Room Temperature, which is officially defined as 20 C to 25 C (68 F to 77 F), with permitted excursions up to 30 C. To maintain product stability, the medicine must be protected from excessive heat, humidity, and moisture. It is strictly prohibited to freeze the product.

Packaging and Child Safety

The medication must be kept in its original container and the container must be kept tightly closed. A critical regulatory requirement is that Surdex must be stored out of the sight and reach of children due to the presence of potent active ingredients.

Disposal Instructions

Disposal of unused or expired Surdex should be handled through an official drug take-back program. As this product is not on the official government flush list, it must not be flushed down the toilet or poured into a drain.

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

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