Metamizol HEXAL is used for the management of symptoms related to increased discomfort. This medication is applied across domains where additional symptomatic support is needed, primarily to help manage severe acute pain, provide relief from visceral spasms, and address fever that may be challenging to handle with other measures.

Control of Severe Acute Pain

This medicine is applied in clinical settings marked by heightened patient distress to address acute, high-intensity pain episodes, such as those occurring after surgery, severe injury, or related to tumor pain. It provides support to help ease the overall burden of symptoms, offering relief when supportive symptom management is appropriate for pronounced discomfort. The medicine is commonly used across conditions presenting with acute episodes, for example, in scenarios involving renal colic or biliary colic.

“It is commonly used across conditions presenting with acute episodes, offering symptomatic relief that helps patients cope more steadily.”

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Quick Fact: Relief for Acute Discomfort

• Symptom Focus: Severe pain, high fever, and spasm-related discomfort.
• Context: Commonly used when symptoms intensify and supportive relief is needed, often in post-traumatic or post-operative scenarios.
• Benefit: Provides support that helps ease the overall symptom burden and contributes to improved comfort.

Regulatory References

1. EMA therapeutic overview

Metamizol HEXAL is a prescription pain and fever reducer indicated for severe acute pain following injury or surgery, colic, cancer pain, and other strong acute or chronic pain where other treatments are unsuitable. It may also be used for high fever unresponsive to other medications.

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Contraindications (Who should NOT use this medicine)

Metamizol HEXAL is contraindicated in several specific situations due to the risk of serious side effects, including a rare but life-threatening blood disorder called agranulocytosis.

Condition	Reason for Contraindication
Allergy/Hypersensitivity	To metamizole, other pyrazolones (e.g., phenazone), or any component of the medication.
Blood Disorders	Impaired bone marrow function or blood-forming disorders (hematopoiesis), or a history of drug-induced agranulocytosis.
Pregnancy/Breastfeeding	Contraindicated in the third trimester of pregnancy and generally throughout pregnancy and breastfeeding due to potential risks to the fetus or infant.
Porphyria	Acute intermittent hepatic porphyria (risk of triggering an attack).
Infants	Generally not recommended for infants under 3 months old or weighing less than 5 kg.

Precautions for Use

Caution is advised and the drug should only be used under strict monitoring in patients with conditions such as low blood pressure, pre-existing cardiovascular diseases, impaired liver or kidney function, and bronchial asthma or chronic urticaria (hives).

Interactions with other medicines and products

Metamizol HEXAL has officially documented interactions primarily related to metabolic enzyme alteration and pharmacodynamic interference, as detailed in regulatory documents.

Pharmacokinetic Interactions (Exposure Reduction)

Metamizole is documented as a moderate to strong inducer of several Cytochrome P450 (CYP) enzymes, specifically CYP2B6, CYP3A4, and CYP2C19. This enzyme induction can result in a reduction in plasma concentrations of co-administered drugs that are substrates for these enzymes, potentially decreasing their clinical efficacy. Examples of interacting substances include the immunosuppressants Cyclosporine and Tacrolimus, as well as psychiatric agents like Sertraline and Quetiapine. Official guidance emphasizes that serum levels of drugs like Cyclosporine must be monitored during co-administration.

Pharmacodynamic and Timing Rules

Metamizole exhibits a pharmacodynamic interference with the antiplatelet effect of low-dose Acetylsalicylic acid (Aspirin) by competing at the COX-1 binding site. To mitigate this effect, a mandatory administration separation is required, with regulatory-aligned guidance recommending administering Acetylsalicylic acid at least 30 minutes before Metamizole intake. Additionally, co-administration with Methotrexate carries an additive risk for haematologic toxicity, and co-administration with Chlorpromazine may result in additive hypothermia.

Central Enzyme Inhibition for Pain and Fever Control

Metamizol is a prodrug whose active metabolites, primarily MAA (Metamizol-active acid), execute a multi-system mechanism. The principal action is the inhibition of the cyclooxygenase-3 ( COX-3) enzyme located predominantly within the central nervous system (CNS). This targeted enzyme blockade reduces the synthesis of Prostaglandin E2 ( PGE2) in the brain and the hypothalamic thermoregulatory center, resulting directly in the reduction of elevated body temperature (antipyresis) and dampening of pain signal transmission (analgesia).

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Spasmolytic and Multi-System Modulation

Metamizol also engages two secondary, complementary mechanisms. The first is a spasmolytic action achieved by modulating intracellular calcium ( Ca^2+) signaling within visceral smooth muscle cells, leading to the relaxation of involuntary muscle spasms. The second involves the modulation of non-prostaglandin pathways, including the Cannabinoid Receptor Type 1 ( CB1) system and the Endogenous Opioidergic System, contributing to multi-system inhibition of pain transmission in the spinal cord and brain. These pathways function in parallel to modulate descending pain signals.

The administration of Metamizol HEXAL is limited to three delivery methods—the oral route (tablets or solution), intravenous (IV), and intramuscular (IM)—depending on the pharmaceutical form prescribed. The dosage regimen is defined by parameters that govern the amount and timing of administration.

For adults and adolescents aged 15 and over (weighing more than 53 kg), a single dose is typically limited to 1000 mg (1 g). Doses must be separated by an interval of 6 to 8 hours and should not exceed a maximum daily intake of 4000 mg for the oral route. The maximum daily dose for parenteral (IV/IM) administration is 5000 mg. Use in children under 15 is determined by body weight, with a single dose generally calculated in the range of 8 to 16 mg/kg. Treatment is typically initiated with the lowest recommended dose. Metamizol is generally designated for short-term use.

Parenteral administration is subject to specific procedural conditions: IV injection must be performed very slowly, and the solution should be warmed to body temperature beforehand. The injection solution is compatible with certain diluents, such as 0.9% saline. For patients with impaired renal or hepatic function, multiple high doses must be avoided, and no dosage adjustment is generally required for administration over a short duration.

Research Evidence / Overview of Studies for Metamizol HEXAL

Evidence for Use in Acute Pain and Spasm-Related Conditions

Research has explored the use of Metamizol in conditions associated with acute or disruptive episodes, such as pain following surgery (postoperative pain) or discomfort linked to smooth muscle spasms (colic). This area of evidence is largely based on Randomized Controlled Trials (RCTs) that examine outcomes related to physical discomfort. Studies monitored changes over short time intervals (hours) in primarily adult patients.

Despite the volume of trials, the research provides insight into short-term changes only. A key limitation is the lack of long-term data, as most research was designed to observe responses over defined, acute timeframes.

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Evidence for Use in Fever Management

Metamizol was evaluated in research exploring its antipyretic function, focusing on outcomes related to systemic or functional imbalance such as elevated body temperature. The studies conducted were generally short-term RCTs and comparative trials. Research highlights changes measured over a few hours in both adult and pediatric populations.

However, evidence is often from single-dose studies, and comparative data is lacking for certain adult cohorts. The evidence quality varies across studies, and many trials offered limited insight into the management of prolonged fever.

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Evidence for Use in Chronic and Complex Pain Situations

Research on conditions with longer duration, such as chronic pain linked to cancer or chronic pancreatitis, is supported by systematic reviews of older, limited RCTs and ongoing trials. Outcomes examined include patient-reported outcomes describing perceived discomfort over intermediate-term follow-up durations (e.g., several weeks).

Certainty remains low for long-term use in these complex conditions. The evidence quality varies across studies, and the available data for these chronic pain contexts is less established than for acute uses.

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Synthesis of Evidence Gaps and Areas of Uncertainty

The research describes group patterns, not personal outcomes, and evidence highlights what is known — and what is still uncertain. Key evidence gaps include: long-term effects not fully established across any major indication due to limited follow-up durations; sample sizes were modest in many reviewed studies; and subgroup findings are uncertain, meaning comparative evidence is lacking for specific patient groups, such as older adults and those with complex pre-existing health issues.

Key Studies & References

1. Metamizole containing medicinal products - Article 31 referral - EMA Assessment Report
2. Metamizole in Chronic Pancreatitis Pain (ClinicalTrials.gov Identifier: NCT01804156)

Common questions about Metamizol HEXAL (FAQ)

Q: How long is it safe to use Metamizol HEXAL?

Official product information indicates that Metamizol is generally designated for short-term use. This designation aligns with available clinical studies, which primarily assess acute, short-duration responses. Research evidence currently highlights that long-term effects are not fully established in available research.

Q: Can I use Metamizol HEXAL if I have liver or kidney problems?

Official regulatory precautions state that Metamizol use in patients with impaired liver or kidney function requires strict monitoring by a healthcare professional. Although no dose adjustment may be required for very short durations of treatment, regulatory documents indicate that multiple high doses of the medication must be avoided for this patient group. The caution reflects the potential impact on the body's ability to clear the drug.

Q: What should I do if I think I have a serious side effect like agranulocytosis?

If symptoms such as fever, chills, sore throat, or painful mucosal sores in the mouth or throat are experienced, these may be signs of a serious blood disorder like agranulocytosis. Official safety instructions state that if these symptoms occur, treatment must be stopped immediately and urgent medical attention should be sought. These serious reactions are not related to the dose and can occur at any time.

Q: What should I do in case of an overdose of Metamizol HEXAL?

Official guidance stresses the need to seek immediate medical attention in case of a suspected overdose. Regulatory documents indicate that supportive measures are often advised to manage an overdose. These measures may include procedures to limit the absorption of the drug and methods to accelerate its removal from the body.

Q: Does Metamizol HEXAL make you drowsy?

Official product information reports that certain adverse events, such as somnolence (drowsiness) and vertigo (dizziness), have been observed in some patients taking Metamizol. The official product information warns that if these effects occur, they may impair the ability to drive or operate heavy machinery. You should consult the package leaflet for detailed warnings regarding these effects.

Official Storage and Disposal Requirements

Storage and disposal instructions for Metamizol HEXAL are strictly defined by regulatory documents to ensure the product's integrity and manage safety.

Storage Component	Regulatory Requirement
Temperature Restriction	Must be stored at a temperature not above 25°C and not in the freezer.
Light Protection	Store in the original package to protect from light.
Shelf Life	Stability is granted for 4 years when stored under the specified conditions.
Child Safety	Must be kept out of the sight and reach of children (store locked up).

Regarding disposal, unused or expired Metamizol HEXAL must be discarded according to local or national regulations for pharmaceutical waste. Regulatory guidance specifies that the product must not be thrown away via wastewater or standard household waste, emphasizing the requirement to avoid release to the environment.