Hyos

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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 Hyos

Property Description
Active Ingredient Hyoscine Butylbromide
Forms Oral Tablet, Solution for Injection
Pharmacological Class Antispasmodic Agent, Anticholinergic
General Purpose Relief of Visceral Spasms
Origin Semisynthetic Derivative

What is Hyoscine Butylbromide and What Type of Drug is It?

Hyos is the medicine containing the active substance Hyoscine Butylbromide, which is scientifically classified as a potent spasmolytic agent. The medication belongs to the anticholinergic pharmacological class, acting as a muscarinic antagonist to influence specific nerve signals controlling muscle contraction.


The core substance, Butylscopolamine, is a semisynthetic derivative of Hyoscine. This unique structure, a quaternary ammonium compound, is a differentiating factor, as it restricts the substance's effect primarily to the periphery, minimizing central nervous system penetration. This targeted action makes the drug a preferred choice for treating localized muscle spasms. It is commonly found as a single-ingredient product, simplifying its use when only a spasmolytic effect is desired.

Understanding the General Purpose of Hyos

The overarching general purpose of Hyoscine Butylbromide is to provide specific relief from acute visceral pain that originates from excessive, involuntary smooth muscle spasms. This makes it the typical choice for scenarios such as sudden, cramping discomfort in the digestive tract.


As a dedicated spasmolytic, its essential action is inducing smooth muscle relaxation. This effect is observed in pharmacological assessments of its role in relieving painful spasms in the abdominal region. By blocking the necessary nerve signals that trigger the spasm, this peripheral action addresses the deep discomfort directly at its source.

Available Forms of Hyoscine Butylbromide

Hyoscine Butylbromide is typically supplied in two primary dosage forms to accommodate the varying clinical needs: the Oral Tablet and a sterile Solution for Injection. The forms define the appropriate routes of administration, which are the oral route for the tablet and the parenteral route (intramuscular or intravenous) for the solution.

What side effects are possible with Hyos?

Possible side effects and safety information

The safety profile of Hyoscine Butylbromide is primarily characterized by effects related to its anticholinergic pharmacological class. Adverse reactions are officially categorized by the system or organ class affected and the frequency of their occurrence, as documented in regulatory labeling.

Frequency-Classified Adverse Reactions

The most frequently reported adverse effects are typically associated with the drug’s peripheral action.

Frequency Category Adverse Reactions
Common Dry mouth, Constipation, Tachycardia, Accommodation disorders (transient visual effects)
Uncommon Skin reactions (e.g., urticaria, rash, pruritus)
Not Known Anaphylactic shock, Anaphylactic reactions, Hypotension, Urinary retention, Mydriasis, Increased intraocular pressure

Serious Adverse Reactions

Official regulatory documents list serious adverse reactions, particularly associated with the injectable form. These include cases of severe anaphylactic shock and anaphylactic reactions, some of which have resulted in fatal outcomes. Severe cardiovascular events such as acute myocardial infarction and cardiac arrest have also been reported in susceptible patients who experienced severe tachycardia or hypotension after parenteral administration.

Population-Specific Safety Considerations

The medicine's regulatory label includes explicit safety constraints for specific populations and disease states. Caution is necessary for patients with pre-existing cardiac disease (such as heart failure or hypertension) due to the risk of exacerbating tachycardia. The drug is generally restricted in individuals with untreated narrow-angle glaucoma or conditions leading to urinary or intestinal outlet obstruction, such as prostatic hypertrophy, due to the risk of aggravation. The use of the intramuscular injection route is contraindicated in patients receiving anticoagulant drugs due to the risk of intramuscular haematoma.

Overdose and Emergency Response

Overdosage of Hyoscine Butylbromide may present as an exaggeration of its peripheral anticholinergic effects, which are officially documented in government regulatory sources. Common manifestations of overdosage include tachycardia (fast heart rate), dry mouth, urinary retention, reddening of the skin, and transient visual disturbances (accommodation disorders). Severe manifestations may include respiratory paralysis, coma, and Cheynes-Stokes respiration.

Regulatory guidance mandates that patients seek immediate medical attention for a suspected overdose. Urgent medical advice must also be sought if severe, unexplained abdominal pain persists or worsens, especially if accompanied by systemic signs such as fever, vomiting, or decreased blood pressure (hypotension).

Severe and life-threatening outcomes reported in official labeling include anaphylactic shock, with the highest risk noted after parenteral (injection) administration. Patients receiving the injection are advised to be kept under observation, and appropriate emergency resources should be readily available.

The official management approach is supportive and symptomatic. For oral overdosage, regulatory documents specify procedural steps such as gastric lavage followed by the administration of activated charcoal. Furthermore, it is officially documented that symptoms of overdosage respond to the use of parasympathomimetics, and catheterisation may be necessary for managing urinary retention.

Therapeutic Uses of Hyos

Main Uses and Benefits

Hyoscyamine may assist with providing supportive relief in conditions presenting with systemic or localized discomfort caused by muscle spasms and hypermotility. As a therapeutic agent, it is utilized where additional symptomatic support is needed to help ease physical tension and distress.

Hyoscyamine is commonly used for managing symptoms that interfere with daily functioning and create noticeable physiological strain. It is used as adjunctive therapy for the symptomatic management of conditions involving episodic or fluctuating manifestations, such as irritable bowel syndrome (IBS) and peptic ulcer disease.

It is also used to help with managing symptoms of increased neurological or muscular activity in the gastrointestinal tract, including spastic colitis, mild dysentery, diverticulitis, and acute enterocolitis. Furthermore, it may be part of symptomatic management for symptoms linked to organ-specific functional stress, such as spasms associated with the urinary tract and acute biliary and renal colic.

This approach contributes to improved comfort during periods of heightened symptoms and may help patients cope more steadily with symptom fluctuations. The supportive relief provided may assist with maintaining functional stability during these disruptive episodes.



Quick Fact: Relief for symptoms related to physical discomfort (spasms)


Regulatory References

  1. National Institutes of Health (NIH) DailyMed overview

Eligibility and Restrictions for Use

The eligibility for Hyoscine Butylbromide (Hyos) is strictly defined by government regulatory documents, which list specific populations for whom use is prohibited or restricted.

Age-Related Eligibility

  • Allowed: Adults and adolescents aged 12 years and older are eligible for use under standard labeled conditions. Children from 6 to 12 years are generally permitted [Source: Medsafe, HPRA].
  • Not Recommended: The oral tablet form is not recommended for children under 6 years of age [Source: HPRA].

Contraindicated Populations (Must Not Use)

Use is contraindicated (prohibited) in patients with specific severe conditions [Source: Health Canada, EMC SmPC]:

  • Gastrointestinal Obstruction: Mechanical stenosis, paralytic or obstructive ileus, or megacolon.
  • Ocular Conditions: Untreated narrow angle glaucoma.
  • Systemic Conditions: Myasthenia gravis or known hypersensitivity to the drug or excipients.

Conditional and Restricted Use

  • Cardiac Risk: The injection route is contraindicated in patients with pre-existing tachycardia, angina, or cardiac failure. Caution is advised in patients prone to tachyarrhythmias or susceptible to urinary outlet obstructions [Source: Health Canada, EMC SmPC].
  • Pregnancy and Lactation: Use during pregnancy and breastfeeding is not recommended due to limited or insufficient human data on potential exposure to the infant [Source: HPRA, EMC SmPC].

These official rules determine the populations allowed for the medicine under label-based conditions.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Official regulatory documentation for Hyoscine Butylbromide outlines interaction patterns primarily driven by pharmacodynamic effects and specific administrative constraints.


Documented Interaction Patterns

Classification Interacting Substance Categories Official Outcome Description
Additive Effects Other Anticholinergic Agents (e.g., Tri- and Tetracyclic Antidepressants, Antihistamines, Amantadine, Quinidine) Co-administration may intensify the overall anticholinergic effects.
Antagonistic Effects Dopamine Antagonists (e.g., Metoclopramide) Concomitant use may diminish the effects of both substances on gastrointestinal motility.
Enhanced Effect Beta-Adrenergic Agents The tachycardic effects (increased heart rate) of these agents may be enhanced.

Interaction-Related Restrictions

Administration of Hyoscine Butylbromide requires adherence to specific restrictions and timing rules as defined in product labeling:

  • Route-Specific Contraindication: Intramuscular injection is contraindicated in patients receiving anticoagulant drugs due to the officially recognized risk of local haematoma formation.
  • Timing Separation: Antacids or adsorbent anti-diarrheals must be administered at least one hour before Hyoscine Butylbromide to prevent the reduction of the latter's absorption.
  • Other Substances: Official product information contains a warning that patients should abstain from alcohol while using this medication. The regulatory profile does not explicitly detail specific pharmacokinetic interactions (e.g., CYP-mediated) as the mechanism for co-administered drugs.

Mechanism of Action

Hyoscyamine, the active component, functions primarily as a competitive antagonist at muscarinic acetylcholine receptors (mAChRs) located on effector cells. Its binding blocks the action of the endogenous neurotransmitter acetylcholine (ACh) at these receptor sites.

This blockade is non-selective, affecting all five subtypes of muscarinic receptors (M1 through M5), though the functional effect is most prominent where M2 and M3 receptors mediate smooth muscle contraction and glandular secretion. The inhibition of M3 receptors in the smooth muscle of the gastrointestinal and urinary tracts leads to a decrease in Gq protein signaling, resulting in reduced intracellular calcium concentration. This molecular cascade diminishes the tone and motility of the smooth muscle tissue.

Furthermore, the antagonism at post-ganglionic cholinergic receptors in exocrine glands reduces their secretomotor activity. The overall physiological consequence of widespread muscarinic antagonism is a general relaxation of smooth muscle throughout the visceral organs and a reduction of glandular secretions.

Dosage and Administration Information

How to Use Hyos (Hyoscine Butylbromide) — Administration Guidelines

Hyoscine Butylbromide is administered using distinct patterns based on the dosage form. The medicine is generally intended for short-term, symptomatic use, and continuous daily intake is not recommended without medical investigation of the cause of the underlying symptoms.

Feature Oral Tablet Instructions (10 mg Strength) Solution for Injection Instructions (20 mg/mL)
Route of Administration Oral Intravenous (IV), Intramuscular (IM), or Subcutaneous (SC)
Standard Adult Dose 10 mg or 20 mg per intake. 20 mg (one ampoule) per injection.
Frequency/Max Dose Up to 4 times daily (maximum 80 mg total daily dose). May be repeated after 30 minutes if necessary. Maximum daily dose is 100 mg.

Specific Administration Rules

Oral tablets must be swallowed whole with water; they should not be crushed, broken, or chewed. For the injectable form, IV administration must be performed slowly. The solution for injection may be diluted with standard 0.9% sodium chloride or glucose solutions for injection when needed for administration. Intramuscular injection is typically avoided in patients receiving anticoagulant drugs due to the risk of haematoma; in such cases, the subcutaneous or intravenous routes may be used.

Age-Group and Missed-Dose Rules

For children aged 6 to 12 years, the dose is typically one 10 mg tablet three times daily. If an oral dose is missed, the standard procedure is to skip the missed dose if it is almost time for the next scheduled dose, and not to take a double dose to compensate.

Recent Clinical Evidence

Research Evidence Overview for Hyoscine Butylbromide

Evidence for Acute Abdominal Cramping and General GI Spasm

Research has extensively examined Hyoscine Butylbromide in the context of acute abdominal cramping and the physical discomfort caused by digestive muscle spasms. Research is informed by short-term Randomized Controlled Trials (RCTs) and systematic reviews that pool data from multiple trials. These studies primarily focused on outcomes related to physical discomfort, measuring the intensity of pain and the reported change in pain intensity shortly after administration. Findings describe patterns related to changes in pain reports compared to inactive substances (placebo) or other treatments used as comparators. Research is limited regarding long-term outcomes and data for specific conditions like abdominal cramping related to acute gastroenteritis.


Evidence for Functional Conditions and Irritable Bowel Syndrome (IBS)

Hyoscine Butylbromide was studied for its application in managing conditions characterized by fluctuating or episodic manifestations, such as Irritable Bowel Syndrome (IBS). RCTs and meta-analyses explored changes in symptoms of Adults with IBS, focusing on patient-reported outcomes describing perceived discomfort like pain, discomfort, and abdominal distension. The quality of evidence for IBS varies across studies, and reviews note that the long-term effects are not fully established, as follow-up durations were limited in many key studies.


Evidence in Acute Organ-Specific Colic and Procedural Use

The injectable form was evaluated in acute contexts involving unstable symptoms, such as renal (kidney) or biliary (gallbladder) colic. These trials primarily examined rapid outcomes like the time needed to achieve measurable change in pain reports. Separately, the medicine was studied for use during diagnostic procedures (e.g., colonoscopy) to induce smooth muscle relaxation, where researchers examined outcomes like the quality of mucosal visualization and procedure time. Evidence describing procedural outcomes has led to mixed findings, and certainty in this area remains low.


What is Still Uncertain About the Research

The research landscape indicates several areas where data are still emerging or where the certainty remains low. Findings were mixed across trials for diagnostic procedures, and there is limited information for long-term outcomes for its use in chronic or recurring conditions like IBS. Furthermore, comparative evidence is lacking in some contexts, and subgroup findings for specific populations like older adults are often uncertain.

Key Studies & References Hyoscyamine Sulfate (DailyMed Drug Information)

Frequently Asked Questions (FAQ)

Common questions about Hyos (FAQ)

Q: How long does it typically take for Hyos to start working after the first dose? / Do you feel the effects of Hyos immediately, or does it take time to build up in the system?

Regulatory information indicates that the active substance from the oral tablet generally reaches its peak level in the bloodstream in about 1 to 2 hours. The medicine is therefore not typically considered an immediate-acting pain relief option. For injection forms, the effect is designed to be much more rapid.

Q: What are the official restrictions or guidelines for older adults using Hyos?

Official regulatory cautions advise that older adults may require special monitoring due to a potentially increased susceptibility to anticholinergic effects. These effects include potential issues like acute urinary retention. These cautions highlight the importance of individual clinical guidance for this population.

Q: Does official labeling indicate that Hyos affects blood pressure readings?

Official documents list hypotension (low blood pressure) as a potential adverse reaction associated with the medication, particularly when given as an injection. This is noted in the 'not known' frequency category in some official labeling.

Q: Does Hyos need to be taken with food, or can it be taken on an empty stomach?

The oral tablet should be swallowed whole with water as directed in the label. Official administration instructions do not specify a requirement that the medicine must be taken with food.

Q: What are the general expectations about the duration of Hyos's effects throughout the day?

Based on the maximum frequency permitted (up to four times per day), the expected duration of the drug's symptomatic effect is typically considered to last in the range of 4 to 6 hours. This expectation guides the recommended interval between doses for symptomatic relief.

Q: Are there different approved formulations of Hyos (e.g., immediate release vs. extended release)?

The oral tablet form of the medicine is generally the standard Immediate Release formulation. This means the active substance is released quickly after swallowing, as the official product information does not describe any controlled-release or extended-release features.

Q: Can Hyos be taken at any time of day, or is a specific time recommended in the official documents?

Official regulatory labeling indicates that the medicine is primarily used for symptomatic relief of visceral spasms. Therefore, its use is typically directed by the occurrence of symptoms, rather than a fixed time of day or night.

Q: Does taking Hyos generally make a person feel drowsy or affect alertness?

The official safety profile notes that adverse reactions can include dizziness and visual disturbances like 'accommodation disorders.' Because these effects may impact focus and vision, they may temporarily impair the ability to perform tasks requiring full attention.

Q: Is Hyos available over the counter, or is it strictly prescription only?

The legal classification of Hyos varies across countries. Depending on the region and the pack size, the product is commonly classified either as a Prescription-Only Medicine or a Pharmacy (P) Medicine that can be purchased under the supervision of a pharmacist.

Q: Where can I find the official regulatory approval information or documentation about Hyos?

Patients can find comprehensive official documentation, such as the Summary of Product Characteristics (SmPC) or the US DailyMed labeling, by searching the public databases of government regulatory bodies like the FDA or EMA.

Q: Is it common for the effectiveness of Hyos to decrease over a long period of time?

Official product warnings advise that continuous daily use of the medicine warrants investigation by a healthcare professional. This is primarily to ensure the symptoms are not masking a more serious, underlying medical condition, as regulatory documents do not explicitly state a decrease in effectiveness (tolerance) over time.

Q: Are there general official recommendations about driving or operating machinery while taking Hyos?

Official regulatory documents explicitly warn that the drug may cause side effects, such as visual problems or dizziness, that could impair the ability to drive or operate machinery. Individuals should consider the potential impact of these effects before engaging in such activities.

Q: Does the product information mention any known effects of Hyos on mental clarity or mood?

The drug is described as having a restricted action, primarily aiming to act outside the brain. However, side effects like confusion have been reported and are categorized within the 'not known' or 'uncommon' frequency category in the official safety profile.

Q: Does the medicine come with a specific Patient Information Leaflet (PIL)?

By regulatory mandate, every package of approved medicine is required to include Patient Information specifically written for the user. In many regions, this is formally known as the Patient Information Leaflet (PIL).

How should Hyos be stored and disposed of?

How to Store and Dispose of Hyoscine Butylbromide (Hyos)

Official regulatory documents define specific environmental controls for storing Hyoscine Butylbromide to ensure product quality and integrity.


Storage Requirements

Condition Requirement
Temperature Store at a temperature not exceeding 30°C; some forms require controlled room temperature (15°C to 30°C).
Protection The product must be protected from light and stored in its original package.
Child Safety Mandatory to keep the medicine out of the sight and reach of children.

Stability and Disposal

The injectable solution is for single use only and any unused content must be immediately discarded. The medicine must not be used after the expiry date. Unused or expired Hyos must not be disposed of in drains or household garbage. Disposal should strictly follow local regulatory requirements for pharmaceutical waste, often requiring return to a pharmacist.

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

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