Opigesic

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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 Opigesic

Property Description
Active Ingredient Acetaminophen (Paracetamol)
Form Oral preparations (tablets, solutions), Rectal, Intravenous
Pharmacological Class Analgesic and Antipyretic
General Purpose Relief of mild to moderate pain and reduction of fever
Origin Synthetic compound (Para-aminophenol derivative)

Opigesic's Core Identity: Active Ingredient and Classification

Opigesic is a pharmaceutical composition that contains the active substance Acetaminophen, which is widely known and used globally as Paracetamol. This drug is classified chemically as a synthetic compound derived from the p-aminophenol group. Acetaminophen is a designated Non-Opioid Analgesic and Antipyretic agent utilized for treating pain and fever, a classification used for its effectiveness in non-inflammatory symptom management. The product is generally available across multiple dosage forms, including traditional oral preparations like tablets and solutions, as well as specialized intravenous and rectal forms used in clinical settings. The formulation utilizes standard pharmaceutical excipients necessary for compound stability and effective delivery.

Pharmacological Role: The Analgesic and Antipyretic Type

The official classification of Opigesic is based on its dual functions: it is an analgesic due to its capacity to relieve pain, and an antipyretic because it reduces fever. This combined action primarily results from its activity within the Central Nervous System (CNS), where it influences pain perception and helps reset the body’s thermoregulatory center. This central action differentiates it from Nonsteroidal Anti-inflammatory Drugs (NSAIDs) as Opigesic exhibits minimal peripheral anti-inflammatory activity.

Its status as an Over-the-Counter (OTC) medication in established dose forms further highlights its utility and broad accessibility. This single-ingredient composition provides effective management for common symptoms, such as the general discomfort associated with a fever.

What side effects are possible with Opigesic?

Possible Side Effects and Safety Information

This information describes the documented safety profile of Opigesic, detailing adverse reactions and limitations as stated in official regulatory labeling.


Documented Adverse Reactions

Adverse reactions are classified by how often they occur and the body system affected:

  • Common Reactions (Very Common / Common): These frequently reported effects often involve the Gastrointestinal System (e.g., nausea, constipation, dry mouth, vomiting) and the Nervous System (e.g., dizziness, sleepiness/drowsiness, headache, trembling). Drowsiness and dizziness may be more pronounced at the beginning of treatment.

  • Serious Adverse Reactions (SAR): Regulatory documents list rare but clinically significant risks, including the potential for Hepatotoxicity (liver damage), Respiratory Depression, and serious Allergic Reactions. The medication also carries a risk of developing Physical and Psychological Dependence with use, even at recommended doses, a factor classified under Psychiatric Disorders.


Population and Safety Limitations

Specific safety considerations apply to certain patient groups and activities:

  • Organ Impairment: Caution is required, and dose adjustment may be necessary for patients with Renal or Hepatic Impairment. Use may be contraindicated in cases of severe hepatic impairment.

  • Pregnancy and Lactation: Use during pregnancy is generally considered unsafe due to the potential for fetal harm. The medication passes into breast milk, requiring monitoring if used during lactation.

  • Activity Restriction: Opigesic can impair concentration and reaction time. Patients are officially advised not to drive or operate heavy machinery during use. Consumption of alcohol is strongly restricted as it can significantly increase side effects like central nervous system depression.

  • Long-Term Monitoring: For patients on prolonged therapy, the label recommends regular monitoring of kidney function, liver function, and levels of blood components.

Overdose and Emergency Response

The official regulatory documents state that an overdose of Opigesic (Acetaminophen/Paracetamol) presents a significant risk due to its potential for delayed organ damage. Initial manifestations, typically within the first 24 hours, are often non-specific, including nausea, vomiting, pallor, and abdominal pain. Symptoms of severe injury, however, can be delayed for up to 48 hours, meaning an individual may feel well while serious damage is developing.

The primary severe outcome documented in regulatory labels is acute liver failure (hepatotoxicity), which may lead to serious complications such as cerebral oedema, haemorrhage, and potentially require liver transplantation or result in death. Acute renal failure is also documented as a potential complication.

Immediate medical advice must be sought and the patient should be referred to a hospital urgently following a suspected overdose, even if the patient feels well. This action is critical because the specific antidote, N-acetylcysteine (NAC), has a defined time-dependent efficacy window for preventing or lessening hepatic injury. The hazard of overdose is documented as greater in individuals with existing risk factors, such as non-cirrhotic alcoholic liver disease or chronic malnutrition. Monitoring involves specialized laboratory testing, including plasma concentration measurements and hepatic function tests.

Therapeutic Uses of Opigesic

What Opigesic Treats: Main Uses and Benefits

Opigesic is applied across domains where additional symptomatic support is needed, primarily focusing on its well-established role in symptomatic relief. This component is commonly used to help with symptomatic relief of pain and is relevant for easing elevated body temperature.

Easing Discomfort and Supporting Stability

Opigesic is commonly used across conditions presenting with acute or episodic manifestations, such as headache, muscular aches, and menstrual cramps, as well as fever associated with seasonal illnesses. Applied in clinical settings that involve acute or unstable symptom patterns, such as the temporary discomfort following minor postoperative procedures or post-vaccination fever, this short-term assistance provides supportive relief that may help patients cope more steadily with symptom fluctuations. This approach contributes to maintaining a sense of stability when symptoms interfere with daily functioning.


Quick Fact: Therapeutic Domain: Mild to Moderate Pain and Fever

Eligibility and Restrictions for Use

Eligibility Profile: Who Can and Cannot Use Opigesic

This information reflects the official population eligibility and non-eligibility rules documented by government regulatory agencies for Opigesic (a drug commonly containing Paracetamol and Orphenadrine Citrate).

Absolute Contraindications

Opigesic must not be used by individuals diagnosed with:

  • Glaucoma.
  • Myasthenia gravis.
  • Prostatic hypertrophy or obstruction at the bladder neck.
  • Oesophageal spasm or pyloric/duodenal obstruction.
  • Documented hypersensitivity (allergy) to paracetamol or orphenadrine citrate.

Age and Life Stage Restrictions

Population Regulatory Status
Children under 12 years Not recommended; safety not established.
Pregnancy Use is not recommended.
Breastfeeding Use is contraindicated/not recommended.
The Elderly Use with caution; a reduced dosage may be advised.

Condition-Based Precautions

Use of this medicine requires caution and may necessitate dose adjustments or monitoring in patients with pre-existing hepatic (liver) or renal (kidney) dysfunction. Caution is also required for patients with certain cardiac conditions, including tachycardia or coronary insufficiency. Safety for continuous, long-term use has not been established and requires periodic monitoring.

What should I know about interactions with other medicines?

Opigesic Interactions with other medicines and products

The following interaction information for Opigesic (Acetaminophen/Paracetamol) is based on documented regulatory constraints and warnings issued by government health authorities. This information is descriptive and not intended as clinical advice.


Official Regulatory Interaction Constraints

The most critical restriction involves the risk of hepatotoxicity (liver damage) from overdose.

  • Prohibited Co-administration: Opigesic must not be taken with any other medicinal product containing acetaminophen (Paracetamol), whether prescription or over-the-counter. This is a formal prohibition to prevent exceeding the safe daily limit.

  • Chronic Alcohol Use: Individuals consuming three or more alcoholic drinks daily are warned against taking Opigesic. This chronic use is officially linked to an increased risk of severe liver injury because alcohol affects the liver enzyme systems (CYP2E1) responsible for metabolizing the drug.

  • Anticoagulant Potentiation: Prolonged daily use of Opigesic, particularly at high doses, may increase the effect of anticoagulants such as Warfarin and other coumarin derivatives. This interaction requires clinical monitoring of blood parameters to ensure safety.

  • Laboratory Test Interference: The drug is officially documented to interfere with certain clinical assays, potentially causing false readings in some blood glucose tests and assays for urinary 5-hydroxyindoleacetic acid (5-HIAA).

  • Population Note: The risk of severe interaction-related injury is officially heightened in patients with pre-existing liver disease.

Mechanism of Action

The mechanism of action for Opigesic, an opioid analgesic, is centered on its interaction with mu-opioid receptors (mu-OR) within the central nervous system, particularly in the brain and spinal cord. The active substance functions as an agonist at the mu-OR, a class of G-protein coupled receptors.

Binding of the drug to the mu-OR triggers the dissociation of the G-protein complex, initiating an intracellular cascade. This action typically leads to the inhibition of adenylyl cyclase, reducing the intracellular concentration of cyclic adenosine monophosphate (cAMP). Furthermore, mu-OR activation promotes the opening of G-protein-coupled inwardly rectifying potassium (GIRK) channels, resulting in potassium efflux and subsequent hyperpolarization of the neuronal membrane. Concurrently, the activation inhibits voltage-gated calcium channels, which reduces calcium influx into the presynaptic terminal.

The net intracellular effect is a decrease in neuronal excitability and a reduction in the release of pronociceptive neurotransmitters, including substance P and glutamate, from primary afferent neurons in the spinal dorsal horn. The system-level consequence is a profound inhibition of ascending nociceptive signaling from peripheral tissues to supraspinal centers, modulating the sensory and affective components of nociception.

Dosage and Administration Information

How to Use Opigesic

Opigesic, which contains Acetaminophen (Paracetamol), is utilized based on specific administration parameters. The medicine is primarily employed on an as-needed (PRN) basis for acute symptom management, and its use is governed by strict dosing limits and time intervals, regardless of the route of administration.


Official Administration Guidelines

Opigesic is available in multiple forms to accommodate various clinical needs. The approved routes include Oral preparations (tablets, solutions), Rectal suppositories, and a parenteral Intravenous (IV) solution. The IV form is reserved for supervised clinical environments where the oral route is not feasible or rapid onset is required.

Dosing and Frequency:

Guideline Instruction
Standard Adult Dose 500 mg to 1,000 mg per administration.
Minimum Interval No less than 4 to 6 hours between successive doses.
Maximum Daily Limit Total intake from all sources must not exceed 4,000 mg in 24 hours.

Procedural Administration Notes

The total daily intake must be strictly monitored to include any other products containing acetaminophen. For Intravenous administration, the solution must be administered by a healthcare professional as a slow infusion over 15 minutes. Oral forms can be taken with or without food, although food may delay absorption.

Population Adjustments: Dosing for children is determined by body weight (mg/kg). Additionally, specific protocols involve dose reductions or extended intervals (e.g., 6 or 8 hours) for patients with severe hepatic or renal impairment.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Opigesic


Evidence for Symptomatic Relief of Mild to Moderate Pain

Opigesic was evaluated in research for mild to moderate acute pain, which includes outcomes related to physical discomfort such as headache, musculoskeletal aches, and temporary discomfort following minor procedures. The research base for this use is extensive and relies heavily on short-term Randomized Controlled Trials (RCTs), supported by systematic reviews and meta-analyses. In these trials, researchers examined patient-reported experiences by using tools like pain intensity scores and recording measurements related to the timing of reported symptom change.

These studies help show what has been observed so far in specific patient groups. Findings describe patterns observed in the studies, where research monitored measured changes in pain intensity scores compared to baseline within the early hours of treatment. Other trials reported patterns related to the use of rescue medication in the acute setting. Research provides insight into short-term changes, but study results reflect the specific conditions under which they were conducted, including varying doses and comparators.


Evidence for the Reduction of Fever (Antipyresis)

Research has also examined Opigesic in the context of elevated body temperature, or fever. The studies exploring short-term symptom changes in this area are mainly Randomized Controlled Trials and Meta-analyses. These trials monitored physiological strain or stress by objectively measuring the Change in Body Temperature from the initial measurement and the Time required to reach a lower temperature.


Gaps in the Research: What is Still Uncertain About Opigesic

Research so far indicates several areas where data for Opigesic are not fully established or remain inconsistent, which is common across many widely used medications.

Long-term effects are not fully established regarding the sustained symptomatic change or the pattern of response when the medication is used regularly over long periods. Comparative evidence is lacking for some of the newer, more specialized formulations. Furthermore, subgroup findings are uncertain, as many major trials were not designed to provide detailed information on certain small patient groups or those with complex, specific underlying conditions.

Key Studies & References

  1. Acetaminophen - StatPearls - NCBI Bookshelf (US Identity and Classification)
  2. Acetaminophen (Oral Route, Rectal Route) - MedlinePlus Drug Information (US Public Resource)

Frequently Asked Questions (FAQ)

Common questions about Opigesic (FAQ)


Q: How long does it usually take for Opigesic to start working?

Official information indicates that oral forms of the active ingredient are described as being readily absorbed. Peak concentrations in the blood typically occur approximately 30 to 60 minutes after the medicine is administered.


Q: What is the average time Opigesic stays in your system?

Most of the medicine is processed and eliminated from the body relatively quickly. Pharmacokinetic data suggests that most of the administered dose is generally eliminated from the system within 24 hours.


Q: Is Opigesic a narcotic or controlled substance?

Opigesic is classified as a Non-Opioid Analgesic and an Antipyretic (fever reducer). This classification is distinct from scheduled narcotics or controlled substances regulated by government authorities.


Q: Is Opigesic safe to use long-term?

Official labeling for over-the-counter use generally restricts the maximum duration of use to a limited number of days unless a healthcare professional advises otherwise. Any long-term or chronic use is described as often necessitating periodic medical monitoring.


Q: What should I do if a side effect seems mild?

If a patient notices a mild side effect or experiences something unusual and is concerned, regulatory guidance suggests consulting with a healthcare professional. Consulting a healthcare professional helps a patient properly discuss the effect.


Q: Is Opigesic approved for use in children under 12?

Official product documentation states that use of Opigesic in children under 12 years is not recommended. This non-recommendation is due to safety for this specific population not having been established in the official product profile.


Q: Is it normal to feel a little dizzy after the first few doses of Opigesic?

Official safety documentation lists dizziness as a common reaction. Official sources note that this effect may sometimes be more noticeable or pronounced when a patient first begins taking the medicine.


Q: Is it common to feel stomach upset after taking Opigesic?

Adverse reaction profiles classify common gastrointestinal effects that can lead to feeling stomach upset. These commonly reported effects include experiencing nausea, vomiting, and abdominal pain.


Q: What happens if I miss a dose of Opigesic?

If a patient is taking the medicine regularly and misses a dose, general health guidance suggests taking the dose as soon as it is remembered, unless the next dose is due within 4 hours. Regulatory guidance states that a patient should not take an extra dose to make up for a missed one.


Q: What is the difference between Opigesic and Opigesic-XL (extended-release)?

Extended-release (XL) formulations are designed to modify the way the medicine is released into the body. These versions typically provide a slower and more sustained delivery of the active ingredient over a longer period compared to standard immediate-release forms.


Q: Have there been any major public health advisories about Opigesic?

Regulatory agencies, such as the FDA, have issued advisories concerning specific safety issues, which can include the potential for rare but serious skin reactions and warnings about counterfeit drug products.


Q: Is there a risk of dependency or withdrawal with Opigesic?

Official safety documentation lists the risk of developing Physical and Psychological Dependence as a Serious Adverse Reaction (SAR). Official safety documentation describes this risk as possible even with use at recommended doses.


Q: Why is Opigesic sometimes prescribed instead of other options?

The medicine is officially classified as an analgesic (for pain relief) and antipyretic (for fever reduction). Its action is centralized in the Central Nervous System, a role that distinguishes it from other drug classes and guides its therapeutic selection.


Q: Is there a maximum amount of time Opigesic is meant to be used?

The label for over-the-counter use generally limits the duration to a short period, such as a few days at a time. Patients on longer therapy are subject to different guidelines and requirements for monitoring as determined by a healthcare professional.


Q: How is Opigesic absorbed by the body?

According to pharmacokinetic information, the oral form of the medicine is readily and efficiently absorbed from the gastrointestinal tract after administration.


Q: Can Opigesic cause dry mouth or changes in taste?

Dry mouth is listed as a common effect in the official adverse reaction profile of Opigesic. Other changes in taste are not consistently documented in core regulatory labeling.


Q: What does the term 'Opigesic research' generally cover?

Official research programs have mainly evaluated the medicine for the symptomatic relief of mild to moderate acute pain and the reduction of fever (antipyresis). Studies focus on short-term symptom changes in specific patient groups.


Q: Do certain medications make Opigesic less effective?

Regulatory documents indicate that the absorption of the medicine may be decreased when it is taken at the same time as other substances. This includes medications that reduce the speed at which the stomach empties its contents.


Q: Are there non-drug interactions to be aware of when using Opigesic?

The primary non-drug interaction cited is chronic alcohol use. Official documents link this pattern of consumption to an increased risk of severe liver injury.


Q: Is Opigesic generally considered safe for people with heart conditions?

Official information states that use requires caution and may necessitate monitoring for patients with certain cardiac conditions. These conditions can include tachycardia (a rapid heart rate) or coronary insufficiency.


Q: How do medical professionals monitor the use of Opigesic?

For patients who are on prolonged therapy, official labels recommend monitoring. Monitoring often involves checking kidney function, liver function, and levels of blood components.


Q: Is there evidence for Opigesic's use in chronic vs. acute conditions?

The research evidence base primarily covers short-term changes in symptoms, focusing on acute pain and fever. This focus aligns with the limited duration of use typically advised on over-the-counter labeling.


Q: Is Opigesic available in liquid or injectable forms?

The medicine is approved in multiple forms to accommodate various needs. These include Oral preparations, such as tablets and solutions, and an Intravenous (IV) solution, which is generally reserved for use in clinical settings.

How should Opigesic be stored and disposed of?

Storage Requirements

Opigesic (Acetaminophen/Paracetamol) must be stored according to regulatory labeling to maintain its stability. The product generally requires storage below 30 C, though certain oral liquid forms are restricted to 20 to 25 C (Controlled Room Temperature). Storage conditions also mandate protection from light, moisture, and extreme heat. Depending on the formulation, the product should be kept tightly closed and remain in its original container and outer carton.

Child-Safety and Disposal

It is a mandatory safety requirement that Opigesic be stored out of the sight and reach of children to prevent accidental ingestion. When disposing of unused or expired medicine, the official recommendation is to utilize a drug take-back program or authorized collection site. If take-back is unavailable, the medicine should be mixed with an undesirable substance (e.g., dirt, coffee grounds) and sealed in a container before being discarded in the household trash; do not throw it into wastewater.

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

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