Nitroxoline

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Nitroxoline

Treatment option: Prostatitis, Urethritis, Cystitis

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 Nitroxoline

Property Description
Active ingredient Nitroxoline (5-nitro-8-hydroxyquinoline)
Form Oral Tablets or Capsules
Pharmacological class Antimicrobial agent, Urinary antiseptic
Common use Systemic anti-infective for the urinary tract
Origin Synthetic (8-quinolinol derivative)

Defining Nitroxoline: Identity, Origin, and Composition

Nitroxoline is a synthetic antimicrobial agent used for its anti-infective properties. The active core is the chemical substance Nitroxoline, formally identified as 5-nitro-8-hydroxyquinoline and often referenced as 5-NOK. Chemically, the drug is classified as an 8-quinolinol derivative, distinguishing its structure from newer generation antibiotics, yet positioning it within a class that has been subject to extensive pharmacological studies.

This medicine is administered as an oral formulation for systemic absorption, typically available as tablets or a capsule, and is considered a single-ingredient product. Commercially, Nitroxoline is sold under various brand names in different regions, such as 5-NOK, Niurox, and Noxin, all sharing this core formulation.

Classification and General Purpose: The Established Urinary Antiseptic

Nitroxoline is classified as a urinary antiseptic, an anti-infective agent specifically targeted toward the urinary system. It is categorized under the Anatomical Therapeutic Chemical (ATC) classification J01XX07 for other antibacterials for systemic use. Its general function is to combat the growth of susceptible microorganisms.

Nitroxoline exerts a dual effect, operating as both a bacteriostatic agent and a fungistatic agent. This mechanism involves the chelation of metal ions essential for microbial survival, a property particularly effective in the urinary tract environment. This overall effect provides the general benefit of supporting the body's effort to clear microbial growth, such as in instances of recurrent or uncomplicated microbial infections.

What side effects are possible with Nitroxoline?

Possible side effects and safety information

The safety profile of Nitroxoline, as detailed in official regulatory documents, is based on a structured classification of documented adverse reactions and use limitations. The drug's safety framework does not include a Black Box Warning, and routine pharmacovigilance is considered sufficient for monitoring its effects.


Documented Adverse Reactions

Adverse reactions associated with the use of Nitroxoline are generally classified in regulatory reports as mild or rare. Specific frequency classifications (such as common or uncommon) for individual side effects are not universally defined across all regulatory abstracts.

System-Organ Class (SOC) Documented Adverse Effect Category
Gastrointestinal disorders Mild disturbances, stomach pain
Immune System disorders Risk of Hypersensitivity reactions

Hypersensitivity to the active substance or excipients is officially considered a serious adverse concern and serves as an absolute contraindication to the medicine’s use.


Safety Restrictions and Contraindications

Official labeling defines specific restrictions where the risk profile is considered unfavorable, preventing the use of Nitroxoline in certain patient groups. These limitations are strictly safety-based, not prescriptive advice.

  • Contraindicated in: Individuals with known hypersensitivity to the active substance or any excipient.
  • Restrictions apply to: Patients with severe renal impairment (glomerular filtration rate less than 30 mL/min) due to the potential for overdose toxicity.
  • Restrictions apply to: Patients with existing disorders of cardiac conduction, such as bradycardia.

Population-Specific Notes

The official documents note that the excretion of Nitroxoline into human breast milk is unknown, which is a key consideration for nursing mothers. Further cautionary notes are included for individuals with rare hereditary problems like fructose intolerance due to excipients.

Overdose and Emergency Response

Overdose and when to seek help

This information outlines the official regulatory statements regarding Nitroxoline overdose and the mandated emergency response procedures.


Documented Overdose Profile

The presentation of an acute overdose in the general population is typically characterized by non-specific manifestations, as regulatory documents do not consistently detail severe systemic symptoms.

The most significant regulatory concern is the potential for drug accumulation that may lead to toxicity in specific patient groups. This risk is primarily documented in individuals with severe renal impairment, defined by a glomerular filtration rate (GFR) less than 30 ml/min. In such circumstances, the potential for adverse effects from systemic drug exposure is elevated.


Emergency Response and Management

Immediate medical attention must be sought following any suspected or confirmed high-level exposure or overdose. This action is explicitly mandated by regulatory authorities.

Management procedures are focused on stabilizing the patient’s clinical status and involve the administration of symptomatic and supportive treatment. Official prescribing information states that no specific antidote is known for Nitroxoline overdose. Therefore, care is directed toward addressing clinical signs and ensuring patient support until the drug is naturally eliminated. Hospital monitoring may be required based on exposure severity and patient risk factors.

Therapeutic Uses of Nitroxoline

Main Therapeutic Uses of Nitroxoline

Nitroxoline is a synthetic antibacterial agent specifically used for the treatment and prevention of urinary tract infections (UTIs). It is classified as a quinoline derivative and has been utilized in clinical practice for several decades due to its targeted action within the urinary system.

Treatment of Urinary Tract Infections

The primary application of nitroxoline is the management of acute and chronic infections of the lower urinary tract. This includes conditions such as:

  • Cystitis: Inflammation and infection of the bladder.
  • Urethritis: Infection of the urethra.
  • Asymptomatic Bacteriuria: The presence of bacteria in the urine in the absence of typical symptoms, when clinical intervention is deemed necessary.

Prevention of Recurrent Infections

In addition to treating active infections, nitroxoline is often used as a prophylactic measure. It may be prescribed to prevent the recurrence of UTIs in individuals who experience frequent episodes. Its role in prevention is supported by its ability to inhibit bacterial adhesion to the walls of the urinary tract.

Key Benefits and Mechanism of Action

Nitroxoline offers several therapeutic benefits that distinguish it from other antimicrobial agents used in urology.

Broad-Spectrum Activity

Nitroxoline exhibits activity against a wide range of pathogens commonly responsible for urinary infections, including:

  • Gram-negative bacteria: Such as Escherichia coli, Proteus species, and Klebsiella species.
  • Gram-positive bacteria: Including certain strains of Staphylococci and Enterococci.
  • Fungal pathogens: It possesses antifungal properties, particularly against Candida species, which can sometimes cause secondary urinary infections.

Targeted Urinary Concentration

Following administration, nitroxoline is rapidly absorbed and primarily excreted through the kidneys. This ensures that the active substance reaches high concentrations in the urine, allowing it to act directly at the site of infection while minimizing systemic impact on the rest of the body.

Inhibition of Biofilm Formation

A significant benefit of nitroxoline is its ability to interfere with the formation of bacterial biofilms. Biofilms are protective layers that bacteria create to shield themselves from the immune system and antibiotics. By preventing the formation of these layers and inhibiting the adhesion of bacteria to the urothelium, nitroxoline helps reduce the likelihood of persistent or chronic infections.

Low Resistance Potential

Due to its unique mechanism of chelating essential metal ions required for bacterial growth, nitroxoline maintains effectiveness against many bacterial strains that have developed resistance to other common antibiotics, such as sulfonamides or certain fluoroquinolones.

Eligibility and Restrictions for Use

Official Eligibility and Contraindications

Eligibility for Nitroxoline is determined by official regulatory documents, primarily focusing on age, organ function, and specific physiological states. The medicine is primarily indicated for use in adults and is available in lower-dose formulations for children and adolescents in regions where it is officially licensed.

Populations Who Must Not Use Nitroxoline (Contraindications)

Contraindication Factual Basis (Regulatory Statement)
Hypersensitivity Known allergy to the active substance (Nitroxoline) or any of the formulation’s excipients.
Severe Renal Dysfunction Individuals with severely impaired kidney function (e.g., GFR below 30 ml/min).
Severe Hepatic Dysfunction Individuals with severe disorders of liver function.

Use is highly restricted and often conditional during pregnancy. The decision to use Nitroxoline in a pregnant patient requires a strict medical assessment due to documented, though uncertain, risks to the fetus. Standard eligibility is otherwise maintained for the general adult population and specific pediatric groups.

What should I know about interactions with other medicines?

Interactions with other medicines and products

The interaction profile of Nitroxoline documents two main types of officially recognized interactions that structure its regulatory use. These interactions involve effects on the efficacy of co-administered drugs and effects on Nitroxoline's own systemic exposure.


Pharmacodynamic Interactions

Co-administration with coumarin-type oral anticoagulants (such as Warfarin or Acenocoumarol) may lead to a pharmacodynamic potentiation, which increases the therapeutic effect of the anticoagulant. Regulatory guidelines state that this combination necessitates close monitoring of coagulation parameters (e.g., INR) to manage the risk associated with heightened anticoagulant activity.

Exposure-Modifying Interactions and Timing Rules

Nitroxoline's action as a chelator of bivalent metal cations creates a clinically significant interaction risk with metal-containing substances. This includes Antacids and mineral supplements such as Iron, Zinc, or Calcium supplements. The interaction forms a chelate complex in the gastrointestinal tract, leading to a reduction in the overall bioavailability and systemic exposure of Nitroxoline. To prevent this outcome, a timing-mandated separation rule is required in regulatory product information: Nitroxoline must be administered at least two to three hours apart from the intake of these metal-containing products.

Mechanism of Action

️ Chelation and Functional Enzyme Blockade

The primary mechanism of Nitroxoline is its action as a high-affinity chelator, binding to essential divalent and trivalent metal ions (such as Zn^2+ and Fe^2+) that serve as cofactors for microbial metalloenzymes. This sequestration functionally inhibits critical microbial machinery, notably Ribonucleotide Reductase (RNR), which disrupts the synthesis of precursors required for DNA replication. This molecular blockade results in the cessation of cell division (bacteriostatic and fungistatic effect) and defines the inhibition of microbial proliferation.


️ Modulation of Microbial Persistence

The drug further modulates microbial virulence by interfering with their ability to adhere and form organized communities. Nitroxoline's mechanism destabilizes the matrix of biofilms and may disrupt Quorum Sensing (cell-to-cell communication) pathways by chelating essential structural metal ions. This action reduces the ability of microorganisms to establish persistent foci, resulting in a decreased microbial population density in the compartment.


Action Constrained by Urinary Concentration

The effectiveness of this mechanism is highly dependent on the drug’s localization within the body. Nitroxoline undergoes rapid metabolism and clearance, leading to high concentrations of the active compound and its metabolites specifically within the urinary tract lumen. This concentration-dependent physiological constraint means the metal-chelating inhibitory action is applied effectively at the site of excretion, but is significantly less relevant for infections outside the urinary compartment due to low systemic tissue penetration.

Dosage and Administration Information

How to Use Nitroxoline: Administration Guidelines

Administration Scope

Nitroxoline is administered via the oral route in the form of tablets or capsules for systemic absorption. Instructions dictate that the medicine should be taken with water, approximately one hour before meals. The solid oral form must be swallowed whole.

Dosing Schedule and Frequency

Dosing regimens are distinct for acute treatment versus prophylaxis. For acute treatment in adults, the standard daily intake is typically 750 mg, which is divided and administered three times per day (TID). For long-term prophylaxis, the regimen uses a lower total daily dose, often ranging from 200 mg to 500 mg, and may be administered as a single daily dose (QD).


Regimen Type Adult Total Daily Dose Frequency Pattern Typical Duration
Acute Treatment 750 mg Three times daily (TID) 5 to 10 days
Prophylaxis 200 mg – 500 mg Often once daily (QD) Several months

Special Administration Rules

Administration for pediatric patients requires a lower, weight-based approach, typically prescribed between 10 to 20 mg per kilogram of body weight per day. In the event that a dose is missed, patients are instructed not to take a double dose to compensate, but rather to continue with the next scheduled administration.

Connection to the Overall Use Protocol

These instructions define the standardized oral delivery method, establish a mandatory pre-prandial timing for administration, and specify distinct dose-frequency patterns tailored for either short-term acute administration or long-term preventive courses, as established for clinical use.

Recent Clinical Evidence

Research evidence / Overview of Studies for Nitroxoline


Evidence for Use in Treating Uncomplicated Urinary Tract Infections (uUTI)

Nitroxoline was studied for its application in uncomplicated urinary tract infections (uUTI) in research that primarily focused on adult females with acute or recurrent episodes. The core evidence for this application was generated by combining data from four separate Randomized Controlled Trials (RCTs) into a large-scale meta-analysis. Researchers designed the studies to be conducted during periods of increased symptom activity, and research explored the agent in comparison to other anti-infective agents.

The main outcomes studied included whether the studies observed microbiological clearance in the urine and the measurement of reported changes in localized symptoms, such as physical discomfort like painful urination. Findings describe patterns observed in the studies related to measurements of microbiological endpoints. The evidence for this application was assigned a moderate level, indicating a specific quality grading. Results apply primarily to the populations studied—adult females with uUTI—and provide limited insight into outcomes for more complicated infections.


Evidence for Use in Preventing Recurrent Urinary Tract Infections (rUTI)

Studies monitored the agent for its application in individuals with a history of recurrent urinary tract infections (rUTI), with research examining its role in preventing subsequent infections. In this context, studies monitored recurrence rates as the main outcome. The evidence base for this preventative approach is less consolidated, and the evidence is considered low to moderate in quality, and data for this application are still emerging.


Gaps in Long-Term Data and Research Uncertainty

The research base is primarily derived from an Individual Patient Data (IPD) meta-analysis combining older trials. A primary limitation is the lack of robust, contemporary, and independently published Randomized Controlled Trials (RCTs). Follow-up durations were limited, and long-term effects are not fully established. Furthermore, data for certain groups, such as children or pregnant individuals, remain insufficient for a structured overview. Certainty remains low for outcomes in patients outside of the primary study demographic.

Key Studies & References WHO ATC/DDD Index: J01XX07 - Other antibacterials for systemic use

Frequently Asked Questions (FAQ)

Common questions about Nitroxoline (FAQ)

Q: How long does it typically take for Nitroxoline to start working?

A: Official information describes Nitroxoline's mechanism as working by chelating metal ions, which helps inhibit microbial growth. This action occurs once the concentration in the urinary tract is sufficient, which is a process that begins shortly after administration. The full clearance of the infection, however, is related to the complete course of treatment.

Q: What should I do if I miss a time to take Nitroxoline?

A: Regulatory documents advise not to take a double dose to compensate for a missed one. Instead, the guidance is to continue with the next scheduled administration at the planned time. Specific management of a missed dose beyond these general rules is subject to a healthcare professional’s guidance.

Q: Does Nitroxoline interact with blood thinners?

A: Yes, official product information indicates that Nitroxoline may interact with coumarin-type oral anticoagulants (often called blood thinners), such as Warfarin. This combination may lead to a potentiation (increase) of the anticoagulant's effect. This risk is noted in regulatory documents, which necessitate close monitoring of coagulation parameters (like INR) when both agents are used.

Q: Can children or teenagers use Nitroxoline?

A: Nitroxoline is indicated for use in adults and is also available in lower-dose formulations for use in children and adolescents in regions where it is officially licensed. Official documentation specifies that dosing regimens for pediatric patients are typically calculated using a weight-based approach.

Q: Can Nitroxoline cause changes in the color of my urine?

A: Yes. According to official product information, the excretion of the active substance via the urine is documented to lead to a noticeable yellow or orange coloration of the urine. This color change is a common observation related to the drug's excretion.

Q: Can Nitroxoline cause dizziness or affect my ability to drive?

A: While documented adverse reactions are generally rare, the possibility of neurological effects such as vertigo (dizziness) has been noted in official reports. Official documents note that these rare reactions may affect the ability to drive or operate machinery.

Q: What information is important to know about Nitroxoline interactions?

A: The key interactions documented in regulatory materials involve two areas: 1. A risk of potentiating the effect of oral anticoagulants. 2. A risk of reduced bioavailability when taken with metal-containing products (like iron supplements or antacids). Regulatory guidance describes a rule of separating the administration of Nitroxoline from metal-containing products by at least two to three hours.

Q: Can people with kidney problems use Nitroxoline?

A: Use of Nitroxoline is contraindicated in patients who have severe renal impairment (severely reduced kidney function). For non-severe kidney function issues, regulatory documents do not list an absolute contraindication; however, use is subject to healthcare professional review.

Q: Can people with liver issues use Nitroxoline?

A: Use is contraindicated for individuals with severe disorders of liver function. For non-severe liver issues, regulatory documents do not list an absolute contraindication; however, use is subject to healthcare professional review.

Q: Is Nitroxoline described as being safe for breastfeeding mothers?

A: Official regulatory documents state that the excretion of Nitroxoline into human breast milk is unknown. This uncertainty is part of the information used by a healthcare professional when reviewing its use.

Q: Is Nitroxoline safe to take during pregnancy?

A: Nitroxoline is generally highly restricted or contraindicated during pregnancy, especially in the first trimester, due to documented, though uncertain, risks to the fetus. Any use during pregnancy is subject to a strict review of the documented risks versus potential benefits.

Q: Does Nitroxoline affect birth control pills?

A: Official regulatory documents do not list hormonal contraceptives (birth control pills) as a consistent, documented interaction that affects the efficacy of the contraceptive itself.

Q: Is there a generic version of Nitroxoline available?

A: Nitroxoline is the active ingredient's chemical name and is commercially available under various brand names in different regions, such as 5-NOK, Niurox, and Noxin. The use of multiple brands suggests the presence of non-proprietary forms.

Q: Does Nitroxoline treat fungal infections?

A: Official documents classify Nitroxoline as an antimicrobial agent that exerts both a bacteriostatic and a fungistatic effect. This means it has the property to combat the proliferation of certain susceptible bacteria and fungi.

Q: Is Nitroxoline a long-term treatment or short-term only?

A: Nitroxoline is officially used for both short-term acute treatment (typically 5 to 10 days) and for long-term prophylaxis (prevention) of recurrent infections. Prophylactic use may extend for several months, depending on the regimen prescribed.

Q: Are there specific symptoms that mean I should stop taking Nitroxoline immediately?

A: The risk of a serious hypersensitivity (allergic) reaction to the medicine is documented. Any signs of a severe allergic reaction, such as swelling of the face, lips, or tongue, or difficulty breathing, are defined in the official documentation as a major safety concern.

Q: Is it normal to feel a bit nauseous after taking Nitroxoline?

A: Gastrointestinal complaints, including nausea, are commonly documented as possible adverse effects in official product information. Regulatory reports indicate that these disturbances generally recede during the course of treatment.

Q: Does taking Nitroxoline help prevent future infections?

A: Yes, Nitroxoline has an established therapeutic indication for prophylaxis (prevention). This means it is officially used in some patient groups to help prevent the recurrence of specific types of urinary tract infections (rUTI).

Q: How does the medicine know where to go in the body?

A: The medicine's action is enabled by its rapid metabolism and clearance, which happens through the kidney. This process leads to a high concentration of the active compound and its metabolites specifically within the urinary tract lumen (the inside of the urinary tract), focusing the therapeutic effect there.

Q: What does 'resistance' mean in the context of Nitroxoline?

A: In the context of antimicrobials, resistance refers to when microorganisms, such as bacteria, are no longer killed or inhibited by the concentration of the medicine. Official documents note that some species, such as Pseudomonas spp., are intrinsically resistant to Nitroxoline.

Q: Is Nitroxoline considered a 'narrow spectrum' or 'broad spectrum' agent?

A: Nitroxoline's antimicrobial spectrum focuses primarily on microorganisms commonly found in urinary tract infections, such as Escherichia coli. However, it is noted to be inactive against certain other species like Pseudomonas spp., which helps to define its targeted use.

Q: What should I know about the safety profile of Nitroxoline?

A: The safety profile is characterized by adverse reactions that are generally mild or rare, primarily involving gastrointestinal disturbances. Official information defines contraindications, which include known hypersensitivity, severe kidney or liver impairment, and existing cardiac conduction disorders.

How should Nitroxoline be stored and disposed of?

How to Store and Dispose of Nitroxoline?

The official regulatory profile for Nitroxoline dictates specific conditions to maintain the quality and safety of the oral formulation.


Storage and Stability Requirements

  • Temperature: Nitroxoline must be stored at a temperature not exceeding 25 C.
  • Protection: The container must be kept tightly closed to protect the medicine from moisture.
  • Child Safety: The product must be stored out of the sight and reach of children (a mandatory requirement).

Disposal Instructions

  • Prohibition: Do not dispose of unused or expired Nitroxoline via wastewater (e.g., flushing down the toilet) or household trash.
  • Official Guidance: Disposal must be completed according to local, regional, and national regulations for pharmaceutical waste. Consult a pharmacist for guidance on proper collection and disposal points.

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

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