Engflag

Hydryllin DM

Quick links to important sections

Hydryllin DM

Hydryllin DM_EN

Treatment option:

Medically reviewed

Laura Arias

Last updated on 22/12/2025

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

Overview of Hydryllin DM

Quick Facts

Property Description
Active Ingredients Dextromethorphan, Diphenhydramine
Form Oral Liquid, Syrup
Pharmacological Class Antitussive, First-Generation Antihistamine
General Purpose Symptomatic relief of non-productive cough and irritation
Origin Synthetic

What is Hydryllin DM and What Type of Medicine is It?

Hydryllin DM is a fixed-dose combination medication formulated for oral administration as a syrup or liquid solution. It belongs to the dual pharmacological classification of an antitussive (cough suppressant) and a first-generation antihistamine, a pairing clinically recognized for simultaneously addressing two primary symptoms of respiratory irritation. This combination structure is designed to offer coordinated relief for persistent, non-productive coughs associated with minor upper respiratory conditions.

Active Ingredients and Dual Classification (Antitussive and Antihistamine)

The therapeutic foundation of the product relies on the two synthetic active ingredients: Dextromethorphan hydrobromide and Diphenhydramine hydrochloride. Dextromethorphan functions as a highly recognized, non-opioid cough suppressant.

The second component, Diphenhydramine, is classified as a first-generation antihistamine. This ingredient's dual function includes blocking histamine receptors to mitigate irritation and providing an auxiliary action known to promote rest, which is often a targeted benefit in cold preparations.

How the Combination Provides General Symptomatic Relief

The combination of a central cough suppressant and a peripheral irritant blocker is intended to provide effective symptomatic relief for the patient. A typical use scenario involves easing the persistent, non-productive cough often experienced during a common cold. The Dextromethorphan component suppresses the frequency of the cough reflex, while the Diphenhydramine component manages the associated rhinorrhea and upper airway secretions, contributing to overall comfort.

Regulatory References

  1. MedlinePlus on Dextromethorphan

What side effects are possible with Hydryllin DM?

Possible side effects and safety information

The safety profile of the Dextromethorphan/Diphenhydramine combination is characterized by effects on the central nervous system (CNS) and physiological effects related to histamine blockade, as classified in government regulatory documents.

Adverse Reaction Scope

Classification Examples of Officially Documented Effects
Common Effects Drowsiness (sedation), Dizziness, Dryness of the mouth, nose, or throat, Nausea, Vomiting, Fatigue.
Rare Effects Confusion, Restlessness, Palpitations, Tachycardia, Severe Hypersensitivity reactions (e.g., anaphylaxis, swelling), Seizures.
Body Systems Affected Nervous System, Gastrointestinal System, Eye Disorders (e.g., blurred vision), Renal and Urinary System (e.g., difficulty in urination), and Cardiac System.

Serious Adverse Reactions and Key Safety Constraints

Official regulatory documents highlight the potential for Serious Adverse Reactions, including Serotonin Syndrome, particularly when the medicine is used concomitantly with certain other medications such as Monoamine Oxidase Inhibitors (MAOIs). Severe Allergic Reactions are also noted as a rare, serious risk.

Because the medicine may cause significant drowsiness and impaired motor skills, official safety information mandates a restriction against engaging in activities requiring mental alertness, such as driving or operating machinery.

Population-Specific Safety Considerations

The regulatory profile specifies safety cautions for certain patient populations. Older adults may be more susceptible to CNS side effects, including confusion and dizziness, as well as anticholinergic effects like urinary retention. In pediatric patients, regulatory documents note the potential for a paradoxical effect, such as increased agitation or excitability, particularly at higher doses.

Overdose and Emergency Response

Overdose involving Dextromethorphan and Diphenhydramine is officially documented to present with a dual spectrum of toxicity affecting the central nervous system (CNS). Manifestations can range from profound somnolence, dizziness, and confusion to paradoxical excitation, hallucinations, and convulsions (seizures). Anticholinergic signs such as mydriasis (fixed and dilated pupils), dry mouth, urinary retention, and hyperthermia are also documented clinical signs.

Life-threatening outcomes include the risk of Serotonin Syndrome, respiratory compromise leading to apnea, and serious cardiac events such as QRS widening and tachycardia. Pediatric patients are specifically noted in regulatory warnings to be more susceptible to CNS stimulation and the risk of severe neurological events.

Official regulatory guidance strictly mandates that individuals seek immediate medical attention and contact emergency services or a Poison Control Center upon any suspicion of overdose. Urgent medical care is required if the person is hallucinating, cannot be awakened, has a seizure, has trouble breathing, or has collapsed. Supportive and symptomatic treatment, including ECG monitoring and the administration of activated charcoal, is the described procedure for management in a healthcare setting.

Therapeutic Uses of Hydryllin DM

Hydryllin DM is used in situations involving certain distressing symptoms across a cluster of common respiratory manifestations. It is applied in contexts where additional symptomatic support is needed to improve comfort during periods of acute discomfort. The combination is commonly used to help with the temporary relief of symptoms related to the common cold, hay fever, or other upper respiratory allergies, which is relevant in contexts involving heightened systemic burden.

This medication may assist with managing symptoms that interfere with daily functioning, such as a dry, irritating cough and nasal congestion. It is relevant in conditions characterized by periods of heightened symptoms such as upper respiratory tract infections or allergic rhinitis. “It helps address symptom clusters that may become intense or disruptive, and may assist with maintaining functional stability during symptomatic phases.”

Its primary role is to support the patient during difficult episodes by easing distress from the cough and to assist with maintaining functional stability by managing stuffiness and a runny nose. This supports patients during episodes of heightened discomfort and may help patients cope more steadily with symptom fluctuations.

Quick Fact: Symptom Management Context
This medication is primarily relevant for episodes involving both a dry cough and associated congestion/allergic symptoms that cluster together, making it helpful in situations where multiple symptoms occur together.

This provides support that helps ease the overall symptom burden during periods when symptoms are more noticeable.

Regulatory References

  1. NIH MedlinePlus overview of Dextromethorphan

Eligibility and Restrictions for Use

Eligibility Map: Who can and cannot use Hydryllin DM — Official Regulatory Information

Category Official Regulatory Status
Populations for whom use is allowed Adults and adolescents 12 years and older (under standard labeled conditions).
Populations for whom use is contraindicated Individuals with known hypersensitivity to either active ingredient or similar antihistamines. Nursing mothers, neonates, and premature infants.
Age-related eligibility rules Contraindicated in children under 12 years for cough and cold symptoms in many jurisdictions; some OTC labels specify under 4 years.
Condition-specific eligibility rules Not for coughs associated with asthma, smoking, or emphysema, or if the cough is accompanied by excessive phlegm (productive cough).
Eligibility-related restrictions Contraindicated for concomitant use with Monoamine Oxidase Inhibitors (MAOIs) or within two weeks of stopping MAOI therapy.
Special Caution Required Patients with pre-existing conditions that are exacerbated by anticholinergic activity, such as angle-closure glaucoma and conditions causing urinary retention (e.g., prostatic hypertrophy).
Pregnancy eligibility status Use with caution and only if clearly needed.

Official prescribing information defines patient eligibility primarily through absolute contraindications that prohibit use in certain high-risk groups, including infants, breastfeeding women, and those taking MAOIs. The profile is further restricted by age limitations, establishing a minimum age of 12 years for routine use in many regions. Conditional use is required for individuals with specific comorbidities like glaucoma and certain bladder conditions, based on the documented properties of the components.

What should I know about interactions with other medicines?

The official interaction profile for Hydryllin DM is defined by formal constraints across specific pharmacokinetic and pharmacodynamic pathways, as documented in government prescribing information.

Contraindicated Combinations and Timing Rules

The combination is strictly contraindicated with Monoamine Oxidase Inhibitors (MAOIs), including those taken for depression. This major interaction carries the official risk of a severe serotonergic syndrome. A mandatory separation period requires that the medicine must not be administered within 14 days of discontinuing MAOI treatment.

Pharmacokinetic and Exposure Alterations

The Dextromethorphan component is metabolized by the CYP2D6 enzyme. Co-administration with potent CYP2D6 inhibitors (such as Quinidine, Fluoxetine, or Paroxetine) is documented to cause a clinically significant pharmacokinetic interaction. This effect results in a multi-fold increase in Dextromethorphan plasma concentration and reduced clearance. Diphenhydramine is itself noted in regulatory documents as a CYP2D6 inhibitor, which must be considered for co-administered substrates.

Pharmacodynamic Interactions and Substance Restrictions

The product exhibits significant additive central nervous system ( CNS) depressant effects with substances like alcohol, opioid analgesics, hypnotics, and other sedatives. Co-use with other anticholinergic drugs may intensify effects such as dry mouth or blurred vision due to the Diphenhydramine component. The regulatory profile notes that interaction risks are particularly heightened in patients with hepatic impairment where the product is formally stated to be contraindicated due to accumulation potential.

Mechanism of Action

Central Modulation of the Cough Reflex Threshold

The antitussive action originates in the Central Nervous System (CNS) as Dextromethorphan engages the Sigma-1 (sigma1) Receptor in the Medulla Oblongata, which houses the cough center. This sigma1 receptor Agonism dampens neuronal excitability, leading to the physiological consequence of elevating the Afferent Cough Threshold. The effect modifies the sensitivity of the central pattern generator, resulting in reduced responsiveness to incoming afferent input.

Peripheral Histaminergic and Secretion Pathway Blockade

The second component, Diphenhydramine, operates on peripheral and autonomic pathways. Its mechanism involves competitive Antagonism at the Histamine H1 Receptor, which inhibits histamine-driven increases in vascular permeability and fluid exudation. Concurrently, M-AChR Antagonism modulates autonomic signaling to exocrine glands, causing a physiological decrease in the volume of mucosal and salivary secretions. The combination thus influences multiple components of the cough reflex arc via distinct central and peripheral receptor systems.

Dosage and Administration Information

The use of Hydryllin DM is defined by guidelines that specify its administration route, dosage schedule, and proper handling. This fixed-dose combination product is designed exclusively for oral administration as a liquid solution or syrup.

Dosage and Frequency Requirements

The standard single dose for adults, the elderly, and children over 12 years is 10 mL. This dose is to be taken every 4 hours as needed for temporary relief. It is a rule that the total quantity administered must not exceed six doses in any 24-hour period.

Procedural and Duration Constraints

Prior to use, the container must be shaken well to ensure uniformity of the active ingredients. The measured dose must be drawn only with the specialized dosing device or cup supplied with the package, rather than a household spoon, to ensure accuracy. The medication is intended for short-term use for temporary symptom relief. If symptoms persist or the non-productive cough lasts more than seven days, use must be discontinued.

Population and Combination Rules

Prescribing information mandates that the product must not be given to children under 12 years old. Furthermore, a constraint tied to proper use is the prohibition against combining this medicine with any other products containing Diphenhydramine or other treatments for coughs and colds. Caution is also specified for its use in patients with hepatic disease.

Recent Clinical Evidence

Hydryllin DM: Recent Clinical Evidence

Mechanism of Action and Core Research

The research suggests that the study drug is a non-hormonal treatment option examined for the management of moderate to severe vasomotor symptoms (VMS) associated with menopause.

Primary Efficacy Studies

The primary evidence base comes from two large Phase III clinical trials (SKYLIGHT 1 and SKYLIGHT 2), which examined outcomes related to VMS frequency and severity.

These studies explored outcomes related to the onset of observed VMS changes, with follow-up data on symptom changes gathered during the 52-week extension phases. Specifically, studies reported that data collected included measurements of VMS frequency starting at the first week of treatment.

Secondary Outcomes

In addition to VMS, the trials also assessed the drug’s potential to affect sleep quality and changes in menopause-related distress, with findings suggesting a statistically significant change in both areas.

Safety and Tolerability Profile

The most commonly reported side effects in the trials included nausea, abdominal pain, and headache. The studies reported the rate of discontinuation due to adverse events.

The studies included women who were not candidates for hormonal therapy. Participants with severe liver impairment were excluded from the studies. The trials assessed the medication across a diverse population of women with VMS.

Comparisons to Other Treatments

Head-to-head research is scarce, but one small study compared it to an SSRI and reported a difference in VMS frequency between the groups.

The combined data contributes to the understanding of this treatment based on the outcomes reported in the trials.

Key Studies & References

  1. Long-term Efficacy and Tolerability of Neurokinin-3 Receptor Antagonist in Vasomotor Symptoms: Results from the SKYLIGHT 2 Extension Study

Frequently Asked Questions (FAQ)

Common questions about Hydryllin DM (FAQ)

Q: How quickly does Hydryllin DM start to work?

Information on the components of Hydryllin DM suggests a relatively fast onset of effect. Official documents indicate that the Diphenhydramine component is quickly absorbed, with its maximum activity reported to occur in approximately one hour after being taken.

Q: What is the expected length of time that the effects of Hydryllin DM last?

Regulatory information indicates the typical duration of effect for the key components. Specifically, the activity of the Diphenhydramine component is generally described in official sources as lasting between four to six hours.

Q: Is Hydryllin DM a cough suppressant or an expectorant?

Hydryllin DM is classified as an antitussive (or cough suppressant) and a first-generation antihistamine. This combination is primarily used to control the cough reflex and manage irritation. It is not classified as an expectorant, which is a medicine used to help clear mucus.

Q: What is the general difference between a cough syrup with 'DM' and one without?

The 'DM' in the name stands for Dextromethorphan. This component is an antitussive, meaning it works by decreasing activity in the part of the brain responsible for causing the cough reflex. Syrups without 'DM' typically rely on different types of ingredients that may focus on soothing the throat or thinning mucus.

Q: Does Hydryllin DM interact with common anxiety or depression medications?

Official drug interaction profiles contain important warnings regarding certain medicines used for depression and anxiety. Use of Hydryllin DM is strictly contraindicated with Monoamine Oxidase Inhibitors (MAOIs). Furthermore, co-administration with certain CYP2D6 inhibitors (which includes some antidepressants) can cause a clinically significant increase in the amount of Dextromethorphan in the bloodstream.

Q: Can Hydryllin DM be taken along with non-steroidal anti-inflammatory drugs (NSAIDs)?

While no direct prohibition of co-use with the NSAID class is officially listed, regulatory warnings exist against combining the product with other medications that increase the risk of CNS or gastrointestinal side effects. Regulatory information notes a prohibition against combining the drug with any other products containing Diphenhydramine or other cough and cold treatments.

Q: Is there a known interaction between Hydryllin DM and alcohol?

Yes. Official regulatory information notes that the product exhibits significant additive central nervous system ( CNS) depressant effects with substances such as alcohol. This is described as potentially intensifying effects like drowsiness and confusion.

Q: Can Hydryllin DM be used while breastfeeding?

Official prescribing information explicitly lists use by nursing mothers as contraindicated (not allowed). This is based on the components potentially passing into breast milk, but the official label only requires the patient to know it is strictly contraindicated.

Q: Is Hydryllin DM described as potentially causing dizziness?

Yes. According to official government documents, dizziness is listed as a common side effect of this combination medicine. This effect is related to the drug's influence on the central nervous system.

Q: Does Hydryllin DM interact with herbal supplements?

Official product warnings generally advise informing a healthcare provider about all medicines, including vitamins and herbal products. This is because regulatory advice indicates that not all possible interactions may be fully listed in the medication guide.

Q: Is it possible for Hydryllin DM to affect sleep patterns?

Yes, official safety data indicates the drug can affect sleep. Drowsiness (sedation) is listed as a common effect. Conversely, regulatory documents also note that restlessness and agitation are potential side effects, particularly in sensitive populations.

Q: Can people with diabetes use Hydryllin DM?

While diabetes is not listed as a formal contraindication, the product is an oral liquid or syrup formulation. Syrup formulations may contain inactive ingredients like sugar or sorbitol, which patients with diabetes may need to consider.

Q: What is the risk of addiction or dependence with Hydryllin DM?

The cough suppressant component, Dextromethorphan, is chemically classified as a non-opioid agent, differentiating it from certain other cough medicines. However, official warnings and literature note that the Diphenhydramine component is associated with a potential for misuse and abuse.

Q: Is Hydryllin DM the same as Hydryllin?

No. Official product information for related lines indicates that Hydryllin DM contains the active ingredients Dextromethorphan and Diphenhydramine. The related product Hydryllin is formulated with a different set of active ingredients.

Q: Does Hydryllin DM contain codeine?

No. Official documents list the active ingredients as Dextromethorphan and Diphenhydramine. The cough suppressant component, Dextromethorphan, is chemically classified as a non-opioid agent and not codeine.

Q: Why does Hydryllin DM have 'DM' in the name?

The 'DM' stands for Dextromethorphan. This is the name of the antitussive (cough suppressant) active ingredient included in the combination product, which acts centrally to reduce the frequency of coughing.

Q: Is it considered safe to take Hydryllin DM with paracetamol (acetaminophen)?

Official labeling prohibits combining Hydryllin DM with any other product that contains Diphenhydramine or other cough/cold treatments. The combination of this product with any other cough or cold medicine is constrained by regulatory documents.

Q: Does Hydryllin DM show up on common drug screening tests?

Some ingredients, particularly Dextromethorphan and Diphenhydramine, have been noted in regulatory and forensic literature to potentially produce a false positive result for certain other compounds on some drug screening tests.

Q: Does Hydryllin DM have any known effects on the heart rate?

Regulatory documents list potential adverse effects on the cardiovascular system. Specifically, Palpitations and Tachycardia (a rapid heart rate) are noted as rare but officially documented effects of the medication.

Q: Is Hydryllin DM effective for coughs related to asthma?

Official regulatory prescribing information explicitly states that the drug is Not for coughs associated with asthma or certain other chronic lung conditions. This is a condition-specific restriction in the product’s label.

Q: Is Hydryllin DM considered a first-line treatment for cough?

Regulatory documents classify the product as an over-the-counter (OTC) option intended for the temporary relief of cough symptoms. This generally places it outside the formal designation of a 'first-line treatment' used in clinical guidelines.

Q: Are there any specific medical conditions that might be worsened by taking Hydryllin DM?

The official product profile notes special caution is required for patients with pre-existing conditions that are exacerbated by the medicine’s anticholinergic activity. These include certain types of angle-closure glaucoma and conditions that cause urinary retention, such as prostatic hypertrophy.

How should Hydryllin DM be stored and disposed of?

Hydryllin DM syrup must be stored strictly according to regulatory labeling to maintain its stability. The product is required to be stored at controlled room temperature, specifically between 20 C to 25 C (68 F to 77 F). The container must be kept tightly closed and protected from environmental extremes; regulatory documents explicitly state Do not refrigerate and Do not freeze. The medicine must also be protected from light and kept out of reach of children.

For disposal, individuals should first check for community drug take-back programs or follow any specific instructions on the prescription label. If these options are unavailable, the medicine should be mixed with an undesirable substance, placed in a sealed container, and then discarded in the household trash. It is required to not flush this medicine down the sink or toilet.

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

Equivalent of Hydryllin DM found in:

A-Z Index: