A practical guide to the next step when treatment has not started to help.
If burning, urgency or frequency has not started to improve after 48 hours of taking an antibiotic for a lower urinary tract infection, arrange a medical reassessment. Do not simply repeat the same prescription or take leftover antibiotics. NICE recommends reviewing the diagnosis, checking for signs of a more serious infection and considering antibiotic resistance. A urine culture may help guide the next treatment.
Message the team on WhatsApp or Ask The Online GP about a review or call 020 3951 3429. If you feel seriously unwell, seek urgent care rather than waiting for an online appointment.
First, check whether this needs urgent care
NICE advises seeking medical help if symptoms worsen rapidly or significantly, do not start to improve within 48 hours of antibiotics, or you become systemically very unwell. Fever can point to an upper urinary tract infection rather than an uncomplicated bladder infection. Pregnancy, suspected prostate involvement and illness in a child change the assessment and treatment pathway.
If you are deteriorating, have fever with urinary symptoms or cannot keep fluids down, seek prompt in-person assessment. An online consultation is not a substitute for emergency care. Tell the clinician if you are pregnant or could be pregnant, and if you have kidney disease or a history of resistant urine infections.
Why an antibiotic may not be helping
Persistent symptoms do not prove that you need a stronger antibiotic. At reassessment, NICE recommends considering alternative diagnoses, symptoms or signs of a more serious illness, and previous antibiotic use that may have led to resistant bacteria.
There are two separate questions: is this still a lower UTI, and is the chosen antibiotic appropriate for the bacteria involved? The answer may require a urine sample, an examination or both. A remote appointment can help decide the next step, but cannot replace a sample or physical examination when one is needed.
Book a GP review. Bring the antibiotic name, dose, start date and any existing test results so the appointment can focus on what has changed.
What happens at the 48-hour review?
The 48-hour point means symptoms should have started to improve, not that every symptom must have disappeared. Worsening at any time is a reason to seek advice sooner.
NICE recommends sending urine for culture and susceptibility testing if this has not already been done, then reviewing treatment when results are available. The clinician should take previous antibiotic use and prior culture results into account. If the bacteria are resistant, treatment may need to change. The safest choice depends on the result and your medical history, not on which medicine sounds strongest.
Do not alter the prescribed dose, stop early or switch to another antibiotic without advice. Ask the prescribing clinician what to do while you wait for reassessment.
Urine culture: what it adds
A culture aims to identify bacteria in the urine. Susceptibility testing helps show which antibiotics are likely to work against them. This is different from using symptoms alone or a quick dipstick test. Tell the clinician which antibiotics you have already taken and follow the collection instructions supplied with the sample kit.
The result must be interpreted alongside your symptoms. NICE's advice is to review antibiotic treatment when culture and susceptibility results are available, using a narrow-spectrum antibiotic where possible. A result is a decision aid, not a prescription by itself.
Your appointment checklist
- Write down when the symptoms began and whether they are improving, unchanged or worse.
- Have the prescription or medicine packaging available, including the dose and time of the first dose.
- Note missed doses, vomiting, side effects and other medicines you take.
- Bring previous urine culture results if you have them.
- Mention pregnancy possibility, kidney problems and previous resistant infections.
- Ask whether you need a urine sample or an in-person examination.
- Ask who will review the result and how a treatment change will be communicated.
A useful consultation ends with a plan: what to do today, what test is needed, who checks it and which changes mean you should seek urgent help.
Speak to The Online GP, call the team or email an appointment enquiry. Do not send urgent symptoms by email and wait for a reply.
Common questions
Should I wait until I finish the course?
Not if symptoms are worsening or have not started to improve within 48 hours. NICE recommends reassessment at that point. You can still need advice even while taking the prescribed medicine.
Does this always mean antibiotic resistance?
No. Resistance is one possibility, but NICE also asks clinicians to consider an alternative diagnosis and a more serious illness. Do not assume the next step is another prescription.
Can an online GP change the antibiotic?
A clinician can review what has happened and decide whether further treatment is appropriate. Prescribing is not guaranteed. A urine result or in-person assessment may be needed before a safe decision can be made.
Can I use antibiotics left from a previous infection?
Do not self-treat with leftovers. The current problem, suitable medicine and course may differ. Arrange a review of the current symptoms and prescription.
Evidence and scope
This guide follows NICE NG109: lower UTI antimicrobial prescribing, recommendations on advice and reassessment, particularly sections 1.1.13 to 1.1.17. It is general information, not a diagnosis or an individual prescribing plan. Antibiotic doses are deliberately not provided here because age, pregnancy, kidney function, suspected kidney or prostate infection and culture results change the decision.
Arrange an appointment with The Online GP. The aim is a clear, safe next step, not an automatic repeat prescription.
Message The Online GP on WhatsApp to arrange a review. If you feel seriously unwell, seek urgent medical care rather than waiting for a message reply.