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What happens if antibiotics don’t work for UTI?

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on Dec 16, 2021.

Official answer



  • If an antibiotic does not treat a urinary tract infection (UTI), the bacteria may have developed antibiotic resistance and your infection may worsen.
  • A UTI may start as a bladder infection (cystitis) and could worsen into a more serious kidney infection (pyelonephritis) or urosepsis (a serious infection throughout your body) that is a medical emergency.
  • If you are having one or more symptoms of a UTI, contact your doctor for a further evaluation. Symptoms may include pain, burning, frequent urination, pain in lower abdomen area, blood in your urine, a fever, pain in your lower back, or nausea and vomiting.
  • Always completely finish taking your course of antibiotics unless your doctor tells you otherwise.

Antibiotic resistance occurs when the bacteria develops a way to block the action of the antibiotic, and the bacteria are not killed. Antibiotic-resistant urinary tract infections (UTIs) may require another type or class of drug treatment. You may have to switch from an oral treatment to a treatment that goes into your veins (intravenous antibiotic).

Some women have recurrent (repeat) urinary tract infections. Your doctor may recommend options to help prevent them, such as changes in birth control, drinking more fluids, use of vaginal estrogen in postmenopausal women, or in some cases, preventive antibiotic treatment. There is no reliable scientific proof that cranberry juice can prevent UTIs.

How does a UTI happen?

A UTI can occur in any area of the your urinary tract, including the kidneys (filter blood to produce urine), ureters (tubes that go from the kidneys to the bladder and carry urine), bladder (stores urine) and urethra (tube that carries urine outside your body). UTIs occur when bacteria gets into your urethra and travels to your kidney.

Risk factors that can increase your chance of having a UTI include:

  • frequent sex
  • having medical conditions like diabetes
  • previous UTI in the last year
  • using spermicide as a method of birth control
  • not being circumcised or having insertive anal sex (for men)

Sometimes your doctor can diagnose your UTI just based on your symptoms. Your doctor might need to confirm if you have a UTI through urine tests and urine cultures. You may also need other tests like blood tests or imaging studies of your urinary tract.

Who is at risk for antibiotic resistance?

Those who have the greatest risk of developing an antibiotic resistant UTI infection include:

  • those weak immune systems (immunosuppressed)
  • people with multiple medical conditions
  • patients recently on antibiotic regimens
  • those who have undergone urinary catheterization
  • older people and people in nursing care facilities or hospitals

Related: Antibiotic Resistance: The Top 10 List

Which UTI antibiotics are resistant?

High rates of antibiotic resistance have been seen with drugs in the penicillin class, such as amoxicillin and ampicillin, some sulfonamides like sulfamethoxazole and trimethoprim (Bactrim DS, Septra DS), and the fluoroquinolone antibiotics (ciprofloxacin).

Antibiotic resistance can be specific to local patterns in the community. Tell your doctor if you have taken an antibiotic in the last 3 months or traveled out of the country. If needed, your doctor can perform a culture and sensitivity test to see which antibiotic might work best for your infection.

Keep taking your antibiotic even if you feel better and you think you don't need your antibiotic anymore, unless your doctor tells you to stop. Only partially finishing your antibiotic may increase your risk of antibiotic resistance and your infection may return quickly.

Learn more: Antibiotics For UTI Treatment - What Are My Options?


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