Stool pH test
Quick answer: This test measures how acidic a stool sample is. Acidic stool can suggest that sugars are not being absorbed well, for example lactose intolerance, especially in children with diarrhoea.
- SampleStool
- TakesA few minutes to collect the sample
- Before the testA fresh stool sample is needed; follow the lab's instructions.
How the test is done
- 1You collect a fresh stool sample in a clean container
- 2For babies, staff may line the nappy with plastic to catch liquid stool
- 3The lab touches pH paper to the stool
- 4The colour of the paper shows the pH
What your results can mean
Reading your report
Your doctor will read the result with your symptoms and other stool tests.
If the result is outside the usual range
An acidic stool can be seen when sugars such as lactose are not absorbed and are fermented in the gut, often in babies or young children with diarrhoea. A less acidic result is usual in most people.
Who usually has this test
Mainly babies and young children with long-lasting watery diarrhoea, where sugar intolerance is suspected.
Risks and aftercare
There are no risks; keep giving your baby fluids as advised if diarrhoea continues.
Names and options
Also called: pH of stool, fecal pH
Listed by the hospital as
- PH, STOOL
Questions about this test
Why is stool pH checked in babies?
In babies with ongoing diarrhoea, an acidic stool can suggest they are not digesting a sugar such as lactose. It helps doctors decide whether a change in feeding should be discussed.
Is stool pH read with other tests?
Yes, it is usually read with the reducing substances test, which looks for unabsorbed sugar. Together they give a clearer picture.
Does the stool sample need to be fresh?
Yes, stool pH changes as it stands. Bring the sample to the lab soon after collecting it.
Related tests
Tamara Hospital & IVF Centre, Rajajinagar
34/3, 10th Cross Road, opp. Vardhaka Sardar Patel School, 1st N Block, 2nd Stage, Rajajinagar, Bengaluru 560010
The hospital is open 24 hours. Call before you come to check the timing for your scan or sample collection.
Get directions ↗IVF Pulse fertility care at Tamara Hospital →
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This page explains each test in general terms so you know what to expect. It is not medical advice: your doctor decides which tests you need and what your results mean. Reference ranges differ between laboratories. Updated 4 November 2026.