uk Health & medical scares diarrhoea dehydration starting • diarrhea dehydration starting • loose stools dehydration • watery diarrhoea feeling dizzy • diarrhoea dark urine • diarrhoea not peeing much • diarrhoea dry mouth thirst • diarrhoea lightheaded standing • vomiting and diarrhoea dehydration • stomach bug dehydration signs • food poisoning dehydration signs • gastroenteritis dehydration worries • can’t keep fluids down • dehydration getting worse • adult dehydration diarrhoea • older adult diarrhoea dehydration • child diarrhoea dehydration worry • dehydration confusion fainting • dehydration dizzy not improving

What to do if…
you have diarrhea with signs of dehydration starting

Short answer

Start rehydrating now with frequent small sips (ideally an oral rehydration solution) and get same-day advice if you cannot keep fluids down or dehydration signs are not improving.

Do not do these things

Do not “push through” without drinking because you’re afraid it will worsen diarrhoea.
Do not chug a large amount quickly if you feel sick—sip little and often instead.
Do not have fruit juice or fizzy drinks to “replace fluids” (they can make diarrhoea worse).
Do not use alcohol to “settle your stomach.”
Do not give children under 12 medicine to stop diarrhoea.
Do not use “stop-diarrhoea” medicines to cover up serious symptoms; if there is bloody diarrhoea/bleeding from the bottom, or you feel severely unwell, get urgent advice first.

What to do now

Switch to “rehydration mode” immediately.
- Take small sips every few minutes.
- If you feel sick or have been sick, start with very small sips and gradually increase.
Use an oral rehydration solution (ORS) if you can.
- Ask a pharmacist for oral rehydration solutions (powders you mix with water).
- Mix it exactly as the packet says.
Do a quick check every hour to see if you’re improving. Look for:
- Urine becoming lighter and more frequent.
- Dizziness on standing settling.
- Mouth/thirst easing.
Use NHS escalation points (don’t wait for it to become extreme).
- Speak to a pharmacist if you (or your child over 5) have dehydration signs such as dark, smelly urine or peeing less than usual.
- Get urgent help from NHS 111 / urgent GP appointment if:
  - you’re confused/disorientated or unusually drowsy,
  - dizziness on standing does not go away,
  - you’re peeing less than normal or have dark yellow urine,
  - you’re breathing quickly or have a fast heartbeat,
  - you still have dehydration signs after using ORS, or
  - you keep being sick and cannot keep fluids down, or
  - you have bloody diarrhoea or bleeding from the bottom.
- Call 999 if someone collapses, is not responding normally, or seems critically unwell.
Reduce spread while you recover.
- Wash hands with soap and water frequently.
- Avoid preparing food for other people, and stay off work/school, until at least 48 hours after diarrhoea/vomiting stops.
If you’re higher-risk, escalate earlier. Get same-day advice via 111 if the unwell person is an infant/young child, older adult, pregnant, immunocompromised, or has significant long-term conditions.

What can wait

You do not need to figure out the exact cause right now.
You do not need to “fix” your diet today—fluids first; eat only if you feel able.
You do not need to decide about tests or antibiotics now; that comes after assessment if symptoms persist or are severe.

Important reassurance

Feeling weak, shaky, or lightheaded can happen quickly with diarrhoea because fluid and salts are being lost. Starting rehydration early is the most helpful first move and often turns things around.

Scope note

First steps only for the next few hours. Ongoing symptoms, worsening dehydration, or higher-risk situations need clinical advice.

Important note

This is general information, not a diagnosis. If you’re unsure whether your symptoms are becoming serious, it’s safer to use NHS 111.

Additional Resources

Support us

What to do if…you have diarrhea with signs of dehydration starting