Why Do I Keep Getting UTIs? Triggers, Options and the Evidence

Two urinary tract infections in six months, or three in a year, is what the NHS calls a recurrent UTI, and the NHS has a plan for it.¹ The measured triggers are sex, spermicide, a new partner, a first UTI as a teenager, a mother who had them and the menopause; the NICE options are vaginal oestrogen after the menopause, a single antibiotic dose for a known trigger, a non-antibiotic prescription tablet and a daily low-dose antibiotic.^{2, 3} This is the urinary page of the Wellgard BV guide.

What counts as a recurrent UTI, and why does it keep happening?

The NHS counts "2 within 6 months, or 3 within 12 months" as recurrent and puts it on its urgent GP list.¹ UTIs are "usually caused by bacteria from poo entering the urinary tract", a woman's short urethra makes that easy, and the triggers below decide how often.¹

A UTI is not BV and not thrush. A UTI is a bacterial infection of the bladder or urethra (burning, urgency, frequency), found on a urine sample, and its treatment is an antibiotic. BV is a shift in the vaginal bacteria (thin grey discharge, fishy smell) and thrush is a yeast (itch, soreness, thick white discharge); both are found on a swab, and the NHS says BV "is usually treated with antibiotic tablets or gels or creams" while for thrush "you'll usually need antifungal medicine".^{4, 5} An ingredient's evidence does not transfer: cranberry's trials are in recurrent UTI only; live cultures' are in BV recurrence after antibiotics (14.8% against 25.5% in ten trials of 1,234 women), not significant for UTI; D-mannose was no better than placebo in 598 UK women.^{6, 7, 8, 9} BV, thrush or a UTI has the table.

What are the triggers? The numbers

Two US studies: 796 young women followed for six months, and 229 women aged 18 to 30 with recurrent UTIs against 253 without.^{2, 10}

After the menopause the lining thins and the protective lactobacilli near the urethra go. In a 1993 trial of 93 postmenopausal women, eight months of intravaginal oestriol brought lactobacilli back in 61% within a month and cut infections from 5.9 to 0.5 per woman per year; NICE says "Do not offer systemic hormone replacement therapy specifically to reduce the risk of recurrent UTI".^{3, 11} Vaginal oestrogen and UTIs after the menopause has the detail.

Is a UTI contagious, and can sex cause it?

A UTI is not a sexually transmitted infection and is not passed between people; the bacteria are your own.¹ Sex is a trigger, not a transmission: it moves bacteria towards the urethra, which is why the risk rose with each day of intercourse in the 796-woman study.¹⁰ The NHS lists peeing soon after sex among its Dos; in that study delayed voiding was not associated with infection, so it is sensible advice rather than a proven shield.^{1, 10} A partner is not tested or given antibiotics.

Which antibiotics does the NHS use for a UTI, and why did mine not work?

The one the culture says will work. NICE lists nitrofurantoin and trimethoprim as first choices for non-pregnant women aged 16 and over, with pivmecillinam and fosfomycin as second choices; amoxicillin appears only where a culture shows the bacteria are sensitive to it, which is why it is not routine.¹² Resistance is why: in one trial, a month on a daily antibiotic took E. coli resistance to trimethoprim and amoxicillin from about 20 to 40% to 80 to 95%.¹³ A pharmacist (women aged 16 to 64) or a GP chooses.¹ If a course has not worked, the next step is a urine sample, not a leftover pack; NICE says switch only if a culture shows resistance and symptoms are not improving.¹² Antibiotics are the treatment, yet "not always needed": a GP may "ask you to wait for 48 hours before getting antibiotics"; can a UTI go away on its own has the figures and the kidney-infection cost of waiting; fever, loin pain, blood in the urine or pregnancy mean no waiting.¹

What does the NHS offer when UTIs keep coming back?

Four options, in NICE's order after the behavioural measures.³ First, in or after the menopause, vaginal oestrogen, which NICE says to consider when behavioural measures alone have not worked, and which is absorbed locally.³ A GP prescribes it as a cream, gel, tablet, pessary or ring; one low-dose estradiol vaginal tablet is also pharmacy-supplied after a pharmacist consultation to women aged 50 and over a year past their last period.^{1, 14} Second, a single antibiotic dose for an identifiable trigger.³ Third, methenamine hippurate, a non-antibiotic prescription tablet: NICE says "Consider methenamine hippurate as an alternative to daily antibiotic prophylaxis", and that cystitis sachets should not be taken with it.³ In the UK ALTAR trial (240 women), infections needing antibiotics ran at 1.38 per person-year on it against 0.89 on a daily low-dose antibiotic, within the trial's non-inferiority margin.¹⁵ Fourth, a daily low-dose antibiotic for up to six months; then a specialist referral.^{1, 3} On a course: taking live cultures with antibiotics and live cultures after antibiotics.

Do cranberry, D-mannose, live cultures or more water help?

One line each; the full table is on the trials of D-mannose and cranberry, graded.

Cranberry: the 2023 Cochrane review of 50 trials found cranberry products reduced UTIs in women with recurrent infections by about a quarter (relative risk 0.74, moderate certainty), the positive trials using 36 mg or more of proanthocyanidins a day for 12 to 24 weeks.^{6, 16} The NHS: "no evidence they help ease symptoms" once infection has started; "If you're taking warfarin, you should avoid cranberry products".¹

D-mannose: the NHS says "there's some evidence it may be helpful" and NICE that women "may wish to try" it; in the largest trial, 598 UK women on 2 g a day or placebo for six months, 51.0% against 55.7% had another UTI, not significant; the earlier positive trial of 308 women had no placebo group.^{1, 3, 9, 17} It is a sugar, and NICE says people taking it should be told about the sugar content.³

Live cultures: in the 2015 Cochrane review of nine small trials they did not significantly reduce recurrent UTIs (relative risk 0.82), and the authors said a benefit could not be ruled out.⁸

Water: 140 premenopausal women drinking under 1.5 litres a day added 1.5 litres for a year and had 1.7 infections against 3.2 (one open-label trial); nothing you drink deals with an infection under way.^{1, 18}

When is a UTI a GP, 111 or 999 matter?

The NHS says ask for an urgent GP appointment or call 111 for: a very high or low temperature or shivering; pain in the lower tummy or the back under the ribs; blood in your pee; symptoms worsening or not improving within 48 hours; two UTIs in six months or three in a year; pregnancy; age 65 or over; diabetes, a weakened immune system or a catheter; a man, or a child aged 15 or younger. Call 999 or go to A&E for confusion, drowsiness or difficulty speaking.¹ In pregnancy NICE says an antibiotic is given straight away after a urine sample, so speak to your midwife or GP first; UTIs in pregnancy has the rest.¹² What cystitis is, Pharmacy First and the five red flags are on the cystitis page, with its FAQ on when recurrence points to something else.

Frequently asked questions

Why do I keep getting UTIs after sex?

Sex moves bacteria towards the urethra; the risk rose to 4.81 times at five days of sex in a week in the university cohort.¹⁰ The NHS advises peeing soon after sex and a non-spermicidal method.¹

What is the best antibiotic for a UTI?

NICE ranks none as best or strongest; the right one is the one a culture shows the bacteria are sensitive to.¹²

Can stress cause a UTI?

No study has measured it: searches in October 2026 found no prospective study of stress and UTI risk in women, and stress is not on the NHS list of causes.¹

Can a UTI go away on its own?

Sometimes: the NHS says antibiotics are "not always needed"; can a UTI go away on its own has the proportions; the red flags mean no waiting.¹

Do probiotics help with UTIs?

In the Cochrane review live cultures did not significantly reduce recurrent UTIs (relative risk 0.82); a benefit could not be ruled out. Their trial record is in BV recurrence after antibiotics: why BV keeps coming back.^{7, 8}

Sources

1. NHS. Urinary tract infections (UTIs), reviewed 11 July 2025. nhs.uk/conditions/urinary-tract-infections-utis.
2. Scholes D, et al. Risk factors for recurrent urinary tract infection in young women. Journal of Infectious Diseases, 2000. PubMed 10979915.
3. NICE NG112. Urinary tract infection (recurrent): antimicrobial prescribing, updated 12 December 2024. nice.org.uk/guidance/ng112.
4. NHS. Bacterial vaginosis, reviewed 19 June 2026. nhs.uk/conditions/bacterial-vaginosis.
5. NHS. Thrush in men and women, reviewed 28 July 2023. nhs.uk/conditions/thrush-in-men-and-women.
6. Williams G, et al. Cochrane Database of Systematic Reviews, 2023. PubMed 37068952.
7. Chieng WK, et al. Probiotics, a promising therapy to reduce the recurrence of bacterial vaginosis in women? Frontiers in Nutrition, 2022. PubMed 36204368.
8. Schwenger EM, et al. Cochrane Database of Systematic Reviews, 2015. PubMed 26695595.
9. Hayward G, et al. D-mannose for prevention of recurrent urinary tract infection among women. JAMA Internal Medicine, 2024. PubMed 38587819.
10. Hooton TM, et al. A prospective study of risk factors for symptomatic urinary tract infection in young women. New England Journal of Medicine, 1996. PubMed 8672152.
11. Raz R, Stamm WE. A controlled trial of intravaginal estriol in postmenopausal women with recurrent urinary tract infections. New England Journal of Medicine, 1993. PubMed 8350884.
12. NICE NG109. Urinary tract infection (lower): antimicrobial prescribing, 2018. nice.org.uk/guidance/ng109.
13. Beerepoot MA, et al. Archives of Internal Medicine, 2012. PubMed 22782199.
14. MHRA. Easier access to locally-applied HRT to treat postmenopausal vaginal symptoms in landmark MHRA reclassification, 20 July 2022. gov.uk/government/news.
15. Harding C, et al. Alternative to prophylactic antibiotics for the treatment of recurrent urinary tract infections in women. BMJ, 2022. PubMed 35264408.
16. Xiong Z, et al. Preventive effect of cranberries with high dose of proanthocyanidins on urinary tract infections. Frontiers in Nutrition, 2024. PubMed 39668896.
17. Kranjčec B, et al. D-mannose powder for prophylaxis of recurrent urinary tract infections in women. World Journal of Urology, 2014. PubMed 23633128.
18. Hooton TM, et al. Effect of increased daily water intake in premenopausal women with recurrent urinary tract infections. JAMA Internal Medicine, 2018. PubMed 30285042.