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UTI antibiotic side effects and resistance

Written by Hi Doctor clinical content teamPublished 12 July 2026

Nausea, diarrhoea and rash can occur. Correct use protects you while reducing avoidable antibiotic resistance.

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DIRECT ANSWER

An online consultation lets an EU-licensed doctor review your case and, if appropriate, issue an electronic prescription; each pharmacy decides whether it can dispense it.

Doctor reply in under 2 hours

Average doctor reply under 2 hours; at night and on public holidays it can take longer, always within 24 hours. A prescription only if appropriate.

EU-licensed doctors

Every case is reviewed by an EU-licensed doctor.

Electronic prescription

Each pharmacy decides whether it can dispense an approved prescription; some do not accept PDF prescriptions.

HOW IT WORKS

From consultation to collection

  1. 1

    Consultation

    Answer a secure medical questionnaire online.

  2. 2

    Doctor reviews

    An EU-licensed doctor personally assesses your case.

  3. 3

    Prescription only if appropriate

    The doctor replies in under 2 hours on average and issues a prescription only if it is clinically appropriate.

  4. 4

    Collect at the pharmacy you choose

    Take an approved prescription to the pharmacy you choose; each pharmacy decides whether it can dispense it.

Most short antibiotic courses are tolerated, but every antibiotic can cause side effects and each has its own restrictions. The purpose of screening is to choose an effective treatment without exposing you, or the wider community, to avoidable harm.

Common effects

Nausea, loose stools, abdominal discomfort, headache and mild skin reactions can occur depending on the medicine. Some antibiotics have specific food, alcohol, sun, kidney or pregnancy precautions. Read the patient leaflet for the exact product rather than applying advice remembered from a previous prescription.

Allergy and serious reactions

A previous side effect such as nausea is not automatically an allergy, while hives, swelling, wheeze or anaphylaxis may be. Describe the original reaction accurately. Severe watery or bloody diarrhoea, jaundice, breathing difficulty, facial or throat swelling, widespread blistering rash or collapse needs urgent medical help.

How resistance develops

Bacteria can survive and spread when antibiotics are used unnecessarily or incorrectly. ECDC advises taking antibiotics only when prescribed and following the dose, frequency and duration. Resistance does not mean your body has become used to the drug; it means the bacteria have changed, which can make future infections harder to treat.

When to seek help

Fever, shaking chills, pain in the back or side under the ribs, vomiting, confusion, pregnancy, visible blood in urine, rapidly worsening symptoms or feeling seriously unwell need prompt in-person assessment. Men, children, people with catheters, kidney disease, reduced immunity or recurrent infections may also need testing and a different care route. Antibiotics left over from another illness are not a safe shortcut.

What to prepare for a medical review

A clinician will ask about burning, frequency, urgency, pain, discharge, blood, fever, pregnancy possibility, recent antibiotics, allergies, kidney function and previous urine-culture results. A urine sample is useful in some situations but is not required for every straightforward lower UTI. The safest choice depends on the likely site of infection and local resistance patterns.

A calm next step

Ask what effects are expected, whether the medicine interacts with your regular treatment and when lack of improvement should trigger review. Report a suspected serious reaction through the relevant national pharmacovigilance route.

Clinical sources used: NHS urinary-tract-infection guidance and European Centre for Disease Prevention and Control information on antimicrobial resistance.

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Written by the Hi Doctor editorial team. General information, not individually reviewed by a doctor.

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