What it does
Nalidix is an antibiotic used to treat certain bacterial infections.
Commonly used for: bacterial infections, urinary tract infections (UTIs)
Read more in plain English ↓Plain-language summary for general understanding - not medical advice. Always follow your pharmacist/doctor.
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Source: Pharmacy and Medicines Regulatory Authority · fetched 2026-04-21 17:37:47 · updated 2026-09-29 04:33:06
About this medicine
Nalidix is an antibiotic used to treat certain bacterial infections.
What it treats
- bacterial infections
- urinary tract infections (UTIs)
How it works
Nalidix works by stopping the growth of bacteria, helping your body to fight the infection.
Who it's for
Nalidix is for people with specific bacterial infections, particularly in the urinary tract.
AI-assisted summary grounded in BNF data - general information only, not medical advice. Always confirm with your pharmacist or doctor.
Clinical monograph: nalidix
Nalidixic acid is a synthetic antibacterial agent belonging to the quinolone class of antibiotics. It is primarily effective against Gram-negative bacteria and is used to treat urinary tract infections (UTIs) and other bacterial infections. Nalidixic acid works by inhibiting bacterial DNA synthesis, thereby preventing bacterial replication and growth.
Indications
- Urinary tract infections
- Bacterial infections caused by susceptible strains
Dosage
Children: Refer to the BNF for Children for specific dosing recommendations based on age and weight.
Adults: Refer to standard treatment guidelines for specific dosing recommendations based on infection type and severity.
Mechanism of action
Nalidixic acid exerts its antibacterial effect by inhibiting the enzyme DNA gyrase, which is essential for bacterial DNA replication, transcription, and repair. By binding to DNA gyrase, nalidixic acid prevents the supercoiling of DNA, leading to disruption of the bacterial cell cycle and ultimately cell death.
Pharmacodynamics
Nalidixic acid has a time-dependent antimicrobial effect, meaning that its efficacy is related to the duration of exposure rather than the peak concentration. The drug demonstrates bactericidal activity against susceptible strains of bacteria, particularly Gram-negative organisms. It is important to note that nalidixic acid is not effective against Gram-positive bacteria or anaerobes.
Pharmacokinetics
Nalidixic acid is well absorbed after oral administration, with peak plasma concentrations occurring within 1 to 2 hours. It is distributed throughout the body tissues, including the kidneys, where it reaches high concentrations. The drug is primarily eliminated via renal excretion, with a half-life of approximately 1 to 2 hours. Dose adjustments may be necessary in patients with renal impairment due to reduced clearance.
Contra-indications
- Hypersensitivity to nalidixic acid or any of its components
- History of tendon disorders related to quinolone use
- Children and adolescents under 18 years of age
- Pregnant women
Adverse effects
- Nausea
- Vomiting
- Diarrhea
- Dizziness
- Headache
- Rash
- Tendinitis
- Tendon rupture
- Photosensitivity
- CNS effects such as seizures or confusion
Interactions
- Antacids containing magnesium, aluminum, or calcium can reduce absorption
- Concurrent use with other drugs that prolong the QT interval may increase the risk of arrhythmias
- Warfarin may have altered anticoagulant effects when co-administered
Precautions
- Monitor for signs of tendinitis or tendon rupture, especially in older patients
- Caution in patients with a history of seizures or CNS disorders
- Use with caution in patients with renal impairment, as dosage adjustments may be necessary
- Avoid exposure to sunlight or artificial UV rays due to photosensitivity
Pregnancy
Nalidixic acid is not recommended during pregnancy due to potential risks to the fetus.
Breast-feeding
Caution is advised as it is not known whether nalidixic acid is excreted in human milk.
Storage
Store at room temperature, away from moisture and heat. Keep out of reach of children.
Formulations
- Nalidixic acid 500 mg tablets
- Nalidixic acid oral suspension
AI-synthesized from BNF references - general information only, not a substitute for professional medical advice or the current BNF. Verify doses with a pharmacist.