Medical Oncologist
CION Cancer Clinics
Dehydration and salt with an ileostomy | CION Cancer Clinics
An ileostomy loses water and salt together, because the large bowel that normally soaks them back in is no longer in the path. Plain water on its own does not replace them, and can make the output worse. This page explains the signs of dehydration to watch for, what to sip through the day, what to avoid, and what changes in the heat, on a journey and during a fast. CION Cancer Clinics’ surgical oncologists in Hyderabad can talk this through with you.
MI
Medically reviewed by Dr. Mohammed ImaduddinConsultant Surgical Oncologist · MBBS, MS (General Surgery), MCh (Surgical Oncology) · last reviewed September 2026, next review due September 2027
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On this page
- Why does an ileostomy dry you out?
- What dehydration looks like with a stoma
- How to drink with an ileostomy
- Drinks that help and drinks that make it worse
- What changes in the heat, on a journey and during a fast?
- Four things families tell us, and what is actually true
- Common questions about dehydration with an ileostomy
The short answer
Why does an ileostomy dry you out?
An ileostomy dries you out because the large bowel, the part of the gut that soaks water and salt back into the body, is no longer in the path. Everything leaves through the stoma still wet and still salty. To stay well you have to put back both the water and the salt, and plain water on its own does not do that.
Why salt is the half people forget
The small bowel absorbs water only when salt and a little sugar are absorbed alongside it. Drink a large glass of plain water and the bowel does the opposite: it pulls salt out of the body into the bowel to balance the water, and both leave in the bag. This is why a person drinking constantly can still become dehydrated, and why the advice sounds back to front.
Who is most at risk
Anyone in the first weeks after the stoma is made, before the small bowel has adapted. Anyone on chemotherapy that loosens the bowel. Older people, who feel thirst less. And anyone in a Telangana summer, working outdoors or sleeping without a fan, because sweat takes water and salt too.
What this page cannot tell you
It cannot tell you how much you personally should drink. That depends on your output, your heart and kidneys, your other medicines and the weather, and your team sets it from a measured output and a blood test. Treat what follows as the general pattern, not your prescription.
If the person is dizzy on standing, passing very little dark urine, or has cramps and confusion, go to the nearest emergency department today and say they have an ileostomy.Spotting it
What dehydration looks like with a stoma
It creeps up over days. Families usually notice the person is quieter and more tired before anyone thinks of the word.
Early signs
Thirst, a dry mouth, a headache, tiredness that a nap does not fix. Urine becomes darker and less frequent. Some people notice their rings or slippers feel loose.
Later signs
Dizziness on standing, a fast pulse, cramps in the calves and hands, and a person who is irritable or muddled. By this stage the kidneys are already under strain, and it needs a doctor the same day.
What the bag tells you
Output that has gone from porridge to water, a bag that needs emptying every hour or two, or a sudden rise in volume are all signs that fluid is being lost faster than it can be replaced.
Worth writing down each day
- How many times the bag was emptied
- Roughly how much came out
- The colour of the urine
What the blood test shows
Low sodium, low potassium and low magnesium are the usual pattern, with kidney figures that have crept up. Your team may check these every few weeks while the stoma is in place, and sooner if you are unwell.
Not sure whether this applies to you?
Ask an oncologistThrough the day
How to drink with an ileostomy
Make the salty drink first thing
Mix an oral rehydration solution exactly as the packet says, or the salty drink your dietitian has written out. Keep it in a bottle you carry. This, not the water jug, is your main drink for the day.
Sip, do not gulp
A large glass at once runs straight through. Small mouthfuls spread across the day are absorbed. Keep plain water for swallowing tablets and for a mouthful when you are hot.
Separate drinking from eating
Drinking a glass with a meal washes food through the bowel faster and thins the output. Many people find it helps to drink between meals rather than during them.
Salt the food
Add salt to rice, dal and curd unless your team has limited salt for your heart or blood pressure. Salted buttermilk, salted lassi and a pinch of salt in lime water are all ways of getting it in.
Side by side
Drinks that help and drinks that make it worse
Helps
Makes it worse
Oral rehydration solution, mixed as directed
Large glasses of plain water
Salted buttermilk or salted lassi
Sweet lassi, fruit juice, sugarcane juice
Thin dal water or clear soup with salt
Coconut water in large amounts
Lime water with salt and a little sugar
Fizzy drinks, energy drinks, strong tea and coffee
Small amounts, often, through the day
Alcohol, which drains fluid and salt
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Real life
What changes in the heat, on a journey and during a fast?
The rules stay the same but the margin shrinks. In summer, or on a bus to a district hospital, the person with an ileostomy is losing water through sweat and through the bag at the same time, and a single missed bottle of salty drink can be the difference between a normal day and a night in casualty.
Hot weather
Carry the rehydration bottle everywhere. Stay in the shade and under a fan in the afternoon. If work is outdoors, ask your team for a letter about rest and shade; many employers will accept it. Notice the urine colour before you feel thirsty, because thirst arrives late.
Travel and pilgrimage
Pack spare bags and ORS packets in the hand luggage, not the boot. Plan where the toilets are. On long journeys, set a phone alarm to sip every half hour. Tell one travelling companion what the warning signs are, so it is not only the patient watching.
Fasting, and who this page does not suit
A full day without fluid is risky with a new ileostomy, especially in summer. Talk to your team, and if you wish a religious adviser, before Ramzan, Karthika or a vrat. None of the drinking advice here applies without change to someone with heart failure or kidney disease; their limits are set by their physician, and more fluid can harm them.
Did you know
Dehydration is one of the commonest reasons a person with a new ileostomy comes back into hospital in the first weeks after rectal surgery. Most of those admissions begin with plain water and a hot day, and most are avoidable with a salty drink and a written output record.
Commonly believed
Four things families tell us, and what is actually true
"More water is always safer."
With an ileostomy, large amounts of plain water pull salt out of the body and both leave in the bag. The safer drink is a salty one, sipped through the day. Plain water is for tablets and a mouthful when you are hot.
"Salt is bad for you, so we have cut it out."
For most people with an ileostomy the problem is too little salt, not too much. Unless your team has limited salt for your heart or blood pressure, you need more than you did before the operation.
"She is not thirsty, so she is fine."
Thirst arrives late, and later still in older people. Urine colour, the number of times the bag is emptied, and how the person feels on standing are all better guides than thirst.
"An ORS packet is only for children with loose motions."
It is exactly the balance of salt and sugar an ileostomy needs, it is cheap, and it is sold at every chemist. Mixed as the packet says, it is the drink most stoma teams recommend first.
Questions we are asked
Common questions about dehydration with an ileostomy
How much should I be drinking each day?
There is no single figure that is right for everyone, and this page cannot give you yours. Your team sets it from your measured output, your blood tests and your other conditions. The general rule is a salty drink sipped through the day, with plain water kept for tablets, and a written record of what comes out.
Can I make my own rehydration drink at home?
Yes, but only from a recipe your dietitian or stoma nurse has written out, because the balance of salt and sugar matters and a guess can make things worse. A chemist's ORS packet mixed exactly as directed is the simplest option and costs very little.
Is coconut water good for an ileostomy?
Not as a main drink. It is high in potassium and sugar and low in sodium, which is the salt an ileostomy loses most. An occasional glass is fine. As the drink you reach for all day, it can make output worse. Salted buttermilk is a better everyday choice for most people.
What colour should the urine be?
Pale yellow, like straw. Darker than that, especially if there is less of it, is an early sign you are behind on fluid. Urine the colour of tea, or very little urine over a day, needs a call to the team or a visit the same day.
Why do I get cramps in my legs at night?
Cramps with an ileostomy are often a sign of low magnesium or low potassium, both of which leave in the output. Tell your team rather than treating it as ordinary tiredness. A blood test shows which is low, and it is usually corrected with a supplement they prescribe.
Does chemotherapy change the advice?
The advice stays the same but the risk goes up, because some chemotherapy drugs loosen the bowel and others cause vomiting. Tell the oncology team about your output at every cycle, and keep the rehydration bottle beside you on treatment days.
Will this get easier once the stoma is reversed?
Usually, yes. Once the large bowel is back in the path it takes over the job of absorbing water and salt, and the special drinking rules can be relaxed. Until then, treat the salty drink as part of your treatment rather than an option.
What should I bring to the clinic if I think I am dehydrated?
Your output record, even a rough one. Every medicine you are taking, including anything bought over the counter. Your discharge summary. And the person who has been watching you at home, because they will have noticed changes you have not.
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Sources
- NHS — Ileostomy: living with
- NHS — Dehydration
- American Cancer Society — Ostomies
- Macmillan Cancer Support — Bowel cancer
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
High Output From an IleostomyWhen the bag fills faster than you can drink, and what the team doesLife With an Ileostomy: How It Differs From a ColostomyWhy an ileostomy carries this risk and a colostomy mostly does notRecovery, Eating and Getting Back to LifeEating and drinking after cancer surgery more generallyCaretaker and Family Guide to SurgeryWhat the person at home should be watching forIleostomy Reversal: Timing and What to ExpectWhen the drinking rules can be relaxed
Talk to us
Not sure whether it is dehydration?
Call the helpline and tell us how the person feels, what the urine looks like and how often the bag is being emptied. A stoma nurse or surgical oncologist will tell you whether it can wait for clinic.