What is the role of urine alkalinisers, such as sodium bicarbonate or potassium citrate, in the treatment of a patient with a urinary tract infection (UTI)?

Urine Alkalinisers Have No Role in Treating Acute UTI and Are Contraindicated in Active Infection

Urine alkalinisers such as sodium bicarbonate or potassium citrate should NOT be used for the treatment of urinary tract infections. In fact, potassium citrate is explicitly contraindicated in patients with active UTI, as the rise in urinary pH can promote bacterial growth and bacterial enzymes may degrade the citrate, rendering it ineffective 1.

Why Alkalinisers Are Contraindicated in UTI

Direct Contraindication from FDA Labeling

• Potassium citrate is contraindicated "in patients with active urinary tract infection (with either urea-splitting or other organisms, in association with either calcium or struvite stones)" 1
• The mechanism of harm is twofold: bacterial enzymatic degradation of citrate reduces its effectiveness, and the rise in urinary pH promotes further bacterial growth 1

Lack of Evidence for Efficacy

• A 2016 Cochrane systematic review found zero randomized controlled trials that met inclusion criteria for urinary alkalisers in symptomatic uncomplicated UTI 2
• The review concluded that "the safety and efficacy of urinary alkalisers for the symptomatic treatment of uncomplicated UTI remains unknown" 2

Guideline Recommendations

• The 2024 European Association of Urology guidelines on urological infections make no mention of urinary alkalinisation as a treatment modality for UTI 3
• The 2015 Australian guidelines for spinal cord injured athletes explicitly state that "sodium bicarbonate, acetazolamide, and ascorbic acid are not useful in preventing UTI in patients with neurogenic bladder" 3

Potential Harm from Alkaliniser-Antibiotic Interactions

Drug Interaction Concerns

• Alkalinising agents can significantly alter the pharmacokinetics of common UTI antibiotics, potentially causing crystalluria with sulfamethoxazole, amoxicillin, and ciprofloxacin 4
• The correlation between maximum theoretical supersaturation and crystalluria reports suggests real clinical risk when these agents are combined 4

The Confusion: Symptomatic Relief vs. Treatment

Historical Use for Dysuria

• One older study (1984) showed that sodium citrate provided symptomatic relief in 80% of women with cystitis symptoms who were initially abacteriuric (no bacterial infection) 5
• However, in patients with persistent bacteriuria, symptoms remained unchanged or worsened with alkalinisation alone 5
• This suggests any benefit is purely symptomatic in non-infected patients, not therapeutic for actual UTI 5

When Alkalinisation IS Appropriate (Not for UTI)

Stone Disease Prevention

• Potassium citrate is indicated for uric acid stones (target pH 6.0) and cystine stones (target pH 7.0-7.5) 1, 6
• This is an entirely different indication from UTI treatment 1

Critical Caveat

• Even for stone prevention, treatment must be discontinued if active UTI develops, as alkalinisation can worsen infection 1

Clinical Bottom Line

Do not recommend or prescribe urinary alkalinisers for UTI treatment. Instead, follow evidence-based guidelines:

• Use appropriate antibiotics based on local resistance patterns (trimethoprim-sulfamethoxazole, nitrofurantoin, or fosfomycin for uncomplicated UTI in women) 3
• Reserve alkalinisation exclusively for stone disease management, and only when active infection has been ruled out 1
• If patients are using over-the-counter alkalinisers for "UTI," counsel them that these products lack evidence for efficacy and may promote bacterial growth 1, 2