Menalgin

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Menalgin

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Medically reviewed

Rosario Oropesa

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 Menalgin

Menalgin is a prescription-only (Rx) medication used for the treatment of severe pain and high fever that has not responded adequately to other therapeutic measures. Its active ingredient is metamizole sodium (also known as dipyrone), a substance classified as an ampyrone sulfonate that is widely used globally outside of the United States.

Metamizole is distinguished by its primary therapeutic properties: potent pain relief (analgesic), fever reduction (antipyretic), and the ability to relax smooth muscles (spasmolytic). This combination of effects makes Menalgin particularly suitable for acute conditions involving both pain and spasms, such as biliary or renal colic-like pain.


Pharmacological Profile and Recognition

The analgesic efficacy of metamizole is primarily mediated by its active metabolites, which work centrally within the nervous system. The mechanism of action is distinct from conventional Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), as it is known to inhibit prostaglandin synthesis and activate other pathways, including endocannabinoid and opioidergic systems. This central action contributes to its powerful pain-relieving effects, a finding supported by pharmacological studies and clinical use in several European and South American countries.

Menalgin is typically available as tablets or solutions for injection, depending on the required speed and severity of the effect. Other common brand names for metamizole are Nolotil (Spain) and Novalgin (Germany). Due to the nature of the active ingredient, Menalgin is reserved for strong acute pain and fever management when alternatives are contraindicated or insufficient.

What side effects are possible with Menalgin?

Possible side effects and safety information

The official regulatory documentation for Menalgin, which contains metamizole sodium, details adverse reactions across several physiological systems and establishes specific constraints on its use. This information is classified by severity and organ system by government health authorities.

Serious and Infrequent Adverse Reactions

The most serious safety concern documented in regulatory labels is agranulocytosis, a severe decrease in white blood cells that can lead to life-threatening infections. Agranulocytosis is typically classified as a rare or very rare reaction in official product information, and it is noted that this risk is not related to the dose administered. Other serious adverse effects documented include aplastic anaemia (a severe blood disorder), anaphylactic shock, and severe skin reactions such as Stevens-Johnson syndrome (SJS) and Toxic Epidermal Necrolysis (TEN). Cases of acute liver failure and hepatitis have also been reported.

General Safety Patterns and System Involvement

Adverse effects are grouped into System-Organ Classes (SOCs), including Blood and Lymphatic System Disorders, Immune System Disorders, Hepatobiliary Disorders, and Vascular Disorders. Less serious documented effects can include nausea, upset stomach, dizziness, and headache. The risk of acute hypotension (low blood pressure) is also cited, especially when the medicine is given rapidly.

Population-Specific Safety Constraints

Regulatory documents outline specific contraindications for certain groups. The medication is contraindicated in the third trimester of pregnancy due to potential adverse effects on the fetal circulatory system and is generally not recommended during breastfeeding. Use is also restricted for infants below three months or those weighing less than five kilograms. Furthermore, the medicine is contraindicated in individuals with a known history of metamizole-induced agranulocytosis or pre-existing bone marrow problems.

Overdose and Emergency Response

The official regulatory documentation for Menalgin (metamizole sodium) strictly defines the manifestations and required emergency actions in cases of acute overdose. Excessive exposure may present with gastrointestinal toxicity and signs of systemic distress, including a significant, dose-dependent drop in blood pressure known as severe hypotension, alongside potential Central Nervous System (CNS) effects. Serious acute outcomes requiring immediate medical attention include shock and signs of renal impairment, such as oliguria or anuria.

The regulator mandates that individuals must seek immediate medical attention upon suspicion of overdose. Furthermore, treatment must be discontinued immediately if symptoms suggestive of a life-threatening complication, such as blood dyscrasia, are observed, as this necessitates urgent specialized hematologic and hospital monitoring. Regarding management, the official labeling confirms that no specific antidote is known for metamizole sodium. Therefore, the primary approach involves symptomatic and supportive treatment. Procedures such as gastrointestinal decontamination and potentially accelerated diuresis are listed options for managing acute intoxication.

Therapeutic Uses of Menalgin

What Menalgin Treats: Main Uses and Benefits

Menalgin is applied across domains where additional symptomatic support is needed, primarily addressing episodes involving heightened discomfort. It is considered relevant for conditions where symptoms may intensify temporarily, such as severe pain, fever, and muscle spasm, when additional symptomatic support is needed.

The medication is commonly used across conditions presenting with acute episodes characterized by symptomatic discomfort, such as moderate to severe pain, dangerously high body temperature (fever), and painful muscle spasms (colic).

“This supportive therapy is applied in clinical settings that involve acute or unstable symptom patterns.”

By assisting with managing these symptom clusters, Menalgin provides supportive relief when symptoms interfere with routine activities. It may assist in making episodes easier to tolerate during phases of increased distress or discomfort.


Quick Fact: Relief for Pain, Fever, and Spasms

This medication is often used when symptoms intensify and supportive relief is needed, relevant when short-term symptomatic assistance is needed.

Eligibility and Restrictions for Use

Who Can and Cannot Use Menalgin? Official Regulatory Information

Menalgin (metamizole sodium) eligibility is strictly defined by regulatory authorities based on patient population, history, and physiological status. Use is contraindicated in patients with a history of agranulocytosis or anaphylaxis related to metamizole, or those with existing impaired bone marrow function or diseases of the haematopoietic system.

Contraindications also apply to individuals with acute hepatic porphyria or a genetically induced deficiency of glucose-6-phosphate dehydrogenase (G6PD). Use is explicitly contraindicated during the third trimester of pregnancy due to risks to the fetus, and the medicine is not recommended for repeated use during breastfeeding.

Age-related eligibility begins at 3 months of age or a minimum body weight of 5 kg; it is contraindicated below this threshold. For fixed-dose forms, use may be not recommended in younger children. Patients with renal or hepatic impairment require conditional use and may need a dose reduction due to possible decreased clearance. Caution is also advised for patients with circulatory instability.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Menalgin (containing Metamizole) has officially documented interactions with several classes of medicines, primarily affecting their concentrations or efficacy, requiring clinical caution and monitoring.


Documented Interacting Medicinal Products and Categories

Category/Product Interaction Implication
Anticoagulants (e.g., Warfarin) Requires close monitoring of blood coagulation parameters (INR/Prothrombin time).
Methotrexate Increased plasma concentration and potential toxicity of Methotrexate; requires close hematologic monitoring.
Ciclosporin Reduced plasma concentration of Ciclosporin; requires therapeutic drug monitoring and dose adjustment.
Low-dose Acetylsalicylic acid (Aspirin) The product may reduce the antiplatelet effect of low-dose Aspirin; co-administration should be avoided if this effect is medically necessary.
Antihypertensives Reduced blood pressure-lowering effect of certain agents (e.g., ACE inhibitors, sartans, diuretics).
Bupropion, Efavirenz, Methadone, Valproate Reduced plasma concentrations of these medicines due to enzyme induction, which may decrease their efficacy.

Official Constraints and Monitoring Requirements

Official regulatory information emphasizes that co-administration with drugs having a narrow therapeutic index necessitates mandatory pharmacokinetic monitoring. Specifically, the product's effect on enzyme systems means plasma level monitoring is required for drugs like Ciclosporin. For patients on oral anticoagulants, there is a requirement for close clinical and laboratory monitoring due to the potential for interaction.

Mechanism of Action

The mechanism is defined by the drug's ability to engage multiple targets within the Central Nervous System ( CNS), including Cyclooxygenase-3 ( COX-3) inhibition and indirect modulation of the CB1 and Opioidergic signaling pathways. This activity activates the brain's descending pain control system and limits the PGE2 mediator that elevates the hypothalamic set point, resulting in reduced central nociceptive signal transmission and a decrease in the hypothalamic set point.

A distinct component of the mechanism involves peripheral action on smooth muscle tissues, where the active metabolites initiate the Nitric Oxide ( NO) cascade. This signaling ultimately activates specific Potassium ( K^+) channels, causing the muscle cell membrane to hyperpolarize and resulting in the induction of smooth muscle relaxation (spasmolysis) in visceral systems.

The drug's overall effect profile stems from the intra-molecular synergy of its metabolites, which simultaneously address two distinct physiological processes: central signal transmission and peripheral muscle tone. This coordinated engagement of both neural modulation and smooth muscle electrophysiology mediates a combined physiological effect.

Dosage and Administration Information

Menalgin (metamizole sodium) is administered via multiple routes, including oral (using tablets, capsules, or drops), intravenous (IV), intramuscular (IM), and rectal (suppositories) forms, to allow flexibility in managing acute conditions.

Treatment involves starting at the lowest recommended dose. For adults and adolescents weighing over 53 kg, the maximum oral daily dose is 4,000 mg; the maximum dose for injection is 5,000 mg. When repeating a dose, a minimum interval of 6 to 8 hours is maintained between administrations.

Administration instructions vary by form. For younger patients, doses are calculated based on body weight, typically within a range of 8 to 16 mg per kg of body weight. Furthermore, the IV administration of the solution requires a slow injection or infusion rate, which is a critical procedural condition. It is recommended that the lowest effective dose be considered for older adults or patients with hepatic or renal impairment. These steps define the structured use protocol for this medicine.

Recent Clinical Evidence

Research evidence / Overview of studies

Mechanism of Action Studies

  • Initial research explored the fundamental activity of the compound.
  • Studies have investigated the compound's characteristics, including its effect on an enzyme in the inflammatory pathway.
  • Research has evaluated whether the compound affects joint function by examining its effects on specific biomarkers.

Efficacy and Outcome Research

  • Research has examined the effects on inflammation, primarily by measuring changes in C-reactive protein (CRP) levels.
  • The effects of the compound on pain have been investigated, with findings suggesting that these changes may be associated with changes in pain perception.
  • The primary research endpoint focused on changes in the severity of symptoms, with studies investigating whether the compound changes the severity of symptoms compared to placebo.
  • A specific study compared the incidence of flare-ups between the study group and the placebo group.

Safety and Tolerability Profiles

  • Clinical trials assessed the compound's safety profile over a six-month period.
  • The most frequently reported side effects in clinical trials included gastrointestinal upset and headache.
  • Specific effects reported in studies included those potentially associated with alertness.
  • The medication was administered in studies with food to assess its impact on tolerability.
  • Research examined the long-term safety through open-label extension studies, with data available up to two years.

Pharmacokinetic Studies

  • Studies of absorption, distribution, metabolism, and excretion (ADME) were conducted.
  • Research examined the absorption rate and overall bioavailability when the compound was administered in combination.
  • This treatment was studied as one of several alternatives in terms of drug clearance profiles.

Key Studies & References

  1. Phase III Randomized, Placebo-Controlled Trial of Menalgin in Symptom and Disease Modification

Frequently Asked Questions (FAQ)

Common questions about Menalgin (FAQ)

Q: Can Menalgin be taken with food, or does it need to be taken on an empty stomach?

Official patient information for the oral forms of the medicine, such as tablets, often states that they can be taken with food or immediately after a meal. Regulatory research has noted administration with food to assess its impact on tolerability.

Q: How long does the effect of one dose of Menalgin last?

Regulatory information for Menalgin specifies that there must be a mandatory minimum interval of 6 to 8 hours between administrations. This interval is consistent with the anticipated duration of the drug’s observed analgesic (pain-relieving) and antipyretic (fever-reducing) effects.

Q: What is the function of the main ingredient in Menalgin?

The active ingredient, metamizole sodium, is described in official sources as having three main therapeutic properties. These functions include potent pain relief (analgesic), fever reduction (antipyretic), and the ability to relax smooth muscles (spasmolytic).

Q: Can Menalgin interact with over-the-counter cold and flu medications?

Official interaction lists often note that Menalgin can interact with other medicines, including certain over-the-counter and non-prescription products. Patient guidelines emphasize the importance of discussing all medicines, including non-prescription products like those for cold and flu, with a healthcare professional.

Q: Can I take Menalgin if I'm already taking a blood thinner?

Regulatory documents state that Menalgin interacts with anticoagulants, such as warfarin, which are commonly referred to as blood thinners. Official documentation requires close monitoring of blood coagulation parameters (like INR/Prothrombin time) by a healthcare professional when co-administering with these drugs.

Q: How long does Menalgin stay in the body after the last dose?

Pharmacological sources indicate that the main active metabolite of the drug, 4-methyl-amino-antipyrine (MAA), has a half-life of approximately 2.6 to 3.5 hours. Official data indicates that this substance has been eliminated from breastmilk within 48 hours in studies following administration.

Q: Why are there warnings about Menalgin and heart health?

Official safety documentation cites the risk of acute hypotension (a sudden drop in blood pressure) as a potential side effect. This concern is particularly noted when the medicine is administered rapidly or in patients who already have circulatory instability.

Q: Does Menalgin have a risk of allergic reaction?

Official safety information documents that serious adverse effects include hypersensitivity reactions, such as anaphylactic shock, a severe allergic response. Severe skin reactions are also documented risks.

Q: Does Menalgin affect blood pressure or heart rate?

Official safety information documents the risk of acute hypotension (low blood pressure) as an adverse effect. The risk of acute hypotension is cited, but changes to heart rate are not explicitly listed in the most frequently reported safety patterns.

Q: Is Menalgin the same kind of medication as aspirin or ibuprofen?

Menalgin is sometimes broadly classified as an atypical Non-Steroidal Anti-Inflammatory Drug (NSAID) or a pyrazolone derivative. However, its primary mechanism of action—how it relieves pain—is understood to be distinct from conventional NSAIDs like aspirin or ibuprofen.

Q: Is Menalgin considered a strong pain reliever?

Official regulatory descriptions of the drug categorize it as having potent analgesic (pain-relieving) and antipyretic (fever-reducing) properties. It is officially indicated for the management of severe pain and high fever when other therapeutic measures are considered insufficient or contraindicated.

Q: How quickly does Menalgin usually start working?

The onset of action is generally described in pharmacological sources as rapid. This suggests that effects often begin shortly after the medicine is administered, which is relevant for managing acute conditions.

Q: Can Menalgin cause drowsiness or affect driving?

Official safety documents list nervous system disorders, including drowsiness and fatigue, as potential side effects. These potential effects are listed in official documents as factors that may influence the ability to drive or operate machinery.

Q: Does Menalgin interact with vitamins or herbal supplements?

Official documentation advises patients to notify their doctor and pharmacist if they are taking any other substances, including herbal tonics, vitamins, supplements, and other non-prescription medicines. This discussion is advised to help healthcare professionals monitor for potential interactions.

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

General patient instructions state that if a dose is missed, it can be taken as soon as possible. However, the administration protocol requires that the minimum time interval until the next scheduled dose is observed.

Q: Is it possible to develop a dependence on Menalgin?

The medicine is generally classified as a non-opioid analgesic. While official information notes its effects on certain systems, official patient warnings do not classify it as a medicine with a dependence risk.

Q: Are there any specific foods or drinks to avoid while using Menalgin?

Official patient instructions generally advise patients not to consume alcohol while using this medicine. This precaution is advised due to the potential for adverse effects.

Q: What does official research say about the long-term use of Menalgin?

Official safety warnings state that the most serious side effect, agranulocytosis (a severe blood disorder), is not related to the dose administered. Clinical trials have assessed the safety profile over periods up to two years.

Q: What should I tell my doctor before starting Menalgin?

Patients should inform their doctor about several medical history items listed in the contraindications and precautions sections. These include any history of allergic reactions to the drug, existing bone marrow problems or blood disorders, and current pregnancy or breastfeeding status.

Q: How is Menalgin eliminated from the body?

Pharmacological documents state that the drug and its metabolites are eliminated from the body primarily through the urine. A smaller proportion is also eliminated through the feces.

Q: Are there any specific laboratory tests required before taking Menalgin?

Official regulatory information emphasizes that patients taking certain co-administered drugs, such as oral anticoagulants, may require close clinical and laboratory monitoring. However, there is no mention of general mandatory tests required before starting the drug.

Q: Is Menalgin available in different forms (e.g., tablet, liquid)?

Yes, official documentation confirms that Menalgin is available via multiple administration routes. These forms include oral options, such as tablets, capsules, or drops, and solutions for injection.

Q: Can Menalgin affect fertility (based on official regulatory documents)?

Official safety information, such as Safety Data Sheets (SDS), may classify the drug as Suspected of damaging fertility or the unborn child. This classification indicates a regulatory caution regarding potential reproductive toxicity.

Q: Is Menalgin considered a prescription drug in all countries?

The medicine is authorized for use in numerous countries, but its regulatory status varies by region. In some areas, it is classified as a prescription-only medicine (Rx), while in others, it may be available over-the-counter (OTC).

Q: Do studies suggest Menalgin works better for acute pain or chronic pain?

Official indications primarily state the medicine is for the treatment of acute severe pain that has not responded to alternatives. Research endpoints that examine its effectiveness typically focus on changes in the severity of symptoms.

How should Menalgin be stored and disposed of?

How to Store and Dispose of Menalgin?

The storage and disposal of Menalgin (metamizole sodium) must adhere strictly to official regulatory guidelines to maintain its stability and ensure public safety.

Storage Conditions

Requirement Official Instruction
Temperature Store below 25 C (77 F). Do not refrigerate or freeze.
Protection Protect from light and moisture.
Container Keep in the original container, with the container tightly closed.
Child Safety Store out of the sight and reach of children.

Disposal Instructions

Unused or expired Menalgin must not be disposed of in household waste or flushed down a toilet. Disposal must be carried out according to local requirements for pharmaceutical waste. This typically involves returning the product to a pharmacy or using an approved medicinal waste collection program.

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

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