> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hi-doctor.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Fosfomycin 3g for cystitis

> How the single-dose fosfomycin sachet works for uncomplicated cystitis, how to take it, side effects, and when it isn't right.

Oral fosfomycin is an antibiotic used for selected acute, uncomplicated lower urinary tract infections. It blocks an early step in bacterial cell-wall production and reaches high concentrations in urine, which is why a single sachet can be enough for an eligible case. Fever, flank pain, pregnancy and recurrent infections can require a different assessment.

## What it is

<Info>
  **Active ingredient:** Fosfomycin · **Form:** Granules for oral solution · **Dosages:** 3 g sachet
</Info>

A common regimen for eligible uncomplicated cystitis is **one 3 g sachet** dissolved in water and taken on an empty stomach. Symptoms should begin easing within days. The indication, regimen and follow-up depend on your history and country guidance — a licensed doctor decides whether it is appropriate, and prescribing is never automatic.

## How it works

It blocks an early step in bacterial cell-wall production and reaches high concentrations in urine.

<CardGroup cols={3}>
  <Card title="Short regimen when suitable" icon="clock">
    Uncomplicated cystitis in an eligible woman may be treated with one prescribed sachet.
  </Card>

  <Card title="Diagnosis checked first" icon="magnifying-glass">
    The review looks for warning signs of kidney infection or a complicated UTI.
  </Card>

  <Card title="Antibiotic stewardship" icon="shield-check">
    It is prescribed only when symptoms, history and local guidance support it.
  </Card>
</CardGroup>

## How to use it

<Steps>
  <Step title="Dissolve one 3 g sachet in water">
    Empty the whole sachet into a glass of water, stir, and drink immediately. Do not swallow the granules dry and do not save part of the prepared solution.
  </Step>

  <Step title="Take on an empty stomach">
    Take it about 2–3 hours before or after food, preferably at bedtime after emptying the bladder. The usual regimen for acute uncomplicated cystitis in women and female adolescents is one single 3 g dose.
  </Step>
</Steps>

### Dose schedule

Take the sachet once at the agreed time. Do not repeat it the next day unless a clinician has issued a different indication. Symptoms should be reassessed if they are worsening or not beginning to improve within 2–3 days. Fever, flank pain, pregnancy, recurrent infection, or infection in men needs a different pathway.

## What has been reported

Diarrhoea, nausea, indigestion, headache and vaginal symptoms can occur. Thrush can also occur. Severe, persistent, or bloody diarrhoea can rarely indicate antibiotic-associated colitis and needs urgent advice — do not self-treat it with anti-diarrhoeal medicine.

<Warning>
  Contact your doctor or seek urgent care for fever, chills, flank or back pain, vomiting, confusion, pregnancy, or feeling acutely unwell — these need prompt assessment. The same applies to a severe allergic reaction, or severe, persistent or bloody diarrhoea.
</Warning>

## Who it is not suitable for

Fosfomycin is not suitable if you have signs of kidney infection, sepsis or a complicated UTI, or if you have severe kidney impairment or a previous serious reaction. Fosfomycin is used for selected susceptible lower urinary infections — one sachet does not suit every urinary symptom and does not treat a kidney infection.

## Storage

Keep in the original package, away from moisture and direct heat, and out of children's reach. Follow the temperature limit on your pack and do not use it after the expiry date.

## How Hi-Doctor handles it

<Steps>
  <Step title="Before treatment">
    Review of symptoms and red flags.
  </Step>

  <Step title="Dose">
    Dissolve the prescribed sachet and take it promptly.
  </Step>

  <Step title="Follow-up">
    Seek review if symptoms persist or worsen.
  </Step>
</Steps>

An EU-licensed doctor reads your questionnaire and answers within 24 hours. If the doctor decides it is not safe to prescribe, the consultation fee is refunded in full. See [pricing](/essentials/pricing) for the current consultation fee.

## Related reading

* [Full fosfomycin guide](https://hi-doctor.ai/guides/fosfomycin) — how to prepare the sachet and recognise symptoms that need a different assessment
* [Urinary tract infection](/library/conditions/urinary-tract-infection) — the condition hub, and the red flags that change the care route
* [Nitrofurantoin](/library/medicines/nitrofurantoin) — another antibiotic a doctor may consider for an uncomplicated lower UTI
* [How a consultation works](/essentials/how-it-works)
* [Safety and eligibility](/essentials/safety)

## Start a consultation

<Card title="Sexual health consultation" icon="stethoscope" href="https://hi-doctor.ai/consultation/sexual-health/1">
  Answer the sexual health questionnaire and a registered doctor reviews it.
  They decide whether treatment is appropriate, which one, and at what dose —
  and declining is a normal outcome. See [what it costs](/essentials/pricing)
  and [how the review works](/essentials/how-it-works).
</Card>

<Warning>
  This page is reference information, not medical advice and not a prescription.
  Whether a medicine is appropriate for you is decided by a registered doctor
  after reviewing your consultation.
</Warning>