Preventive antibiotics for recurrent UTIs increase the risk of antibiotic resistance
11 February 2026
Prescribing daily preventive antibiotics for women with recurrent urinary tract infections (UTIs) increases the risk of developing antibiotic resistance, finds a new study. The research, conducted at Cardiff University, is the first large-scale UK study to quantify this risk in routine clinical practice.
Current guidelines recommend daily low-dose preventive antibiotics for recurrent UTIs when other forms of treatment have failed. However, Cardiff University researchers have identified evidence that may influence future guidance and patient–clinician decision-making.
In this new study, the scientists used the SAIL Databank – a secure databank that holds anonymised health data for the whole population of Wales – to assess the risks and outcomes for 48,297 women with recurrent UTIs, including 839 who had received preventive antibiotics.
Dr Leigh Sanyaolu, Health and Care Research Wales and National Institute for Health and Care Research (NIHR) Doctoral Fellow at Cardiff University, said: “Recurrent urinary tract infections - defined as two or more urinary tract infections in six months or three or more in 12 months – affect around 6% of women in the United Kingdom and can have a substantial impact on daily life. Daily antibiotics are currently recommended for the prevention of recurrent urinary tract infections where other options have failed.”
Few studies have assessed the impact of long-term preventive antibiotic use on antibiotic resistance in routine clinical practice. Our aim was to understand and quantify this risk in women with recurrent UTIs, especially as antibiotic resistance is a growing global concern.
The study found no evidence that preventive antibiotics increased the risk of hospital admission with an antibiotic-resistant infection or antibiotic-resistant urinary infection. However, the use of preventive antibiotics did increase the risk of antibiotic resistance in urine tests.
The team found that the risk of developing antibiotic resistance on urine culture to at least one antibiotic was 30.6% in those prescribed preventive antibiotics compared with 23.7% in those who were not. This means that for every 14.6 people treated, one additional person will experience antibiotic resistance. The risk of developing antibiotic resistance to two or more antibiotics on urine culture was 22.0% in those prescribed preventive antibiotics compared with 14.0% in those who were not, meaning that 12.5 people need to be treated for one additional person to experience harmful effects.
Our study provides valuable new evidence on the risks of preventive antibiotic use for recurrent UTIs. This information is important for patients and their clinicians when discussing prevention options, and for policy-makers developing future guidelines.
The study Prophylactic antibiotics to prevent recurrent UTIs and risk of antibiotic resistance: target trial emulation using the SAIL Databank is published in the Lancet Obstetrics, Gynaecology, & Women’s Health.
The researchers note that further work is needed in other population groups to build on their study, with more research also needed to improve understanding of how the risk of antibiotic resistance develops over time with differing durations of preventive treatment.
