Diarrhoea persistent causes in infants
Informed by recognized medical guidance
Overview
Persistent diarrhoea in infants means loose, watery stools that last for 7 days or longer. It can lead to dehydration and weight loss if not managed well.
Key facts
- Persistent diarrhoea lasts more than a week — longer than acute (short-term) diarrhoea.
- The most common cause is an infection that is not clearing up, but food allergies and gut problems can also be responsible.
- Infants are at higher risk of dehydration because of their small body size.
Yes, persistent diarrhoea is fairly common in infants, especially in the first year of life, and often happens after a bout of acute gastroenteritis.
It mainly affects babies and young children under two years old, especially those with weakened immune systems or poor nutrition.
Symptoms
- signs of severe dehydration: no wet nappy for 6 to 8 hours, sunken eyes, dry mouth, crying without tears
- baby is very drowsy or difficult to wake
- blood in the stool that is dark or looks like coffee grounds
- ⚠baby is vomiting frequently and cannot keep fluids down
- ⚠diarrhoea lasts more than 7 days without improvement
- ⚠baby has a high fever (over 38°C / 100.4°F) that does not come down
Common symptoms
- frequent, watery, or loose stools lasting more than a week
- stools may contain mucus or blood
- baby may be fussy, have a low appetite, or lose weight
Symptoms in children
- older children (toddlers) may complain of stomach cramps or bloating
- they may pass stool urgently or have accidents
- weight loss or slowing of growth
Symptoms in older adults
- persistent diarrhoea is less common in older adults, but can occur due to infections, medication side effects, or chronic conditions
Causes
Main causes
- infection (viral, bacterial, or parasitic) that does not clear up
- cow's milk protein allergy or other food allergies
- conditions that affect digestion, such as coeliac disease or cystic fibrosis
Risk factors
- being under 6 months old
- being bottle-fed rather than breastfed
- weakened immune system due to illness or malnutrition
- recent use of antibiotics
When to see a doctor
See a doctor urgently if:
- signs of dehydration (see emergency symptoms)
- baby is unusually sleepy or irritable
- blood in the stool
Book a routine appointment if:
- diarrhoea that lasts more than 7 days
- poor weight gain or weight loss
- stools that are very watery, foul-smelling, or contain mucus
Diagnosis
A doctor will ask about your baby's symptoms, feeding, and nappy changes. They may check for dehydration and order a stool test if needed.
Tests that may be done
- stool test to look for infection or signs of inflammation
- blood test to check for anaemia or signs of infection
- breath test or allergy testing if food intolerance is suspected
What to expect at your appointment
The doctor will ask about the colour, consistency, and frequency of stools, and whether the baby has been vomiting or has a fever. They may also weigh the baby to check for growth problems.
Treatment
Treatment focuses on preventing dehydration and finding the cause. Most babies can be managed at home with extra fluids and feeding adjustments.
Self-care at home
- continue breastfeeding or formula feeding as usual – do not stop
- offer small, frequent feeds of breastmilk or formula
- if advised by your doctor, an oral rehydration solution (ORS) can replace lost fluids and salts
- do NOT give plain water to infants under 6 months without medical advice
Medical treatments
A doctor may prescribe oral rehydration salts or recommend a temporary change to a special formula if an allergy is suspected. Antibiotics are only used if a bacterial infection is confirmed. Never use anti-diarrhoea medicines for infants without a doctor's advice.
When is surgery considered?
Surgery is rarely needed for persistent diarrhoea in infants. It may be considered if there is a structural problem in the bowel, such as a blockage.
Living with this condition
Caring for a baby with persistent diarrhoea can be exhausting. Keep a diary of feeds, nappy changes, and symptoms to share with your doctor. Make sure your baby gets plenty of rest.
Lifestyle tips
- wash your hands carefully after changing nappies to avoid spreading infection
- clean the nappy area with warm water and gentle cream to prevent nappy rash
- make sure the baby is dressed comfortably and not too hot or cold
Diet and exercise
For breastfed babies, continue breastfeeding on demand. For formula-fed babies, your doctor may suggest a different formula. Gentle tummy massage can help comfort a gassy baby, but avoid vigorous activity until the diarrhoea settles.
Mental health and emotional wellbeing
Caring for a sick baby can be stressful and exhausting. It is normal to feel worried or frustrated. Reach out to your partner, family, or health visitor for support.
Prevention
You cannot always prevent persistent diarrhoea, but you can lower the risk. Good hand hygiene, safe food preparation, and breastfeeding for the first six months help protect against infections.
Vaccines
The rotavirus vaccine is given to babies in many countries and helps prevent one of the most common causes of severe diarrhoea.
Screening programmes
No routine screening is needed, but if your baby has ongoing diarrhoea, your doctor may recommend tests to rule out underlying conditions.
Complications
If left untreated
- dehydration – a serious lack of fluids and salts in the body
- electrolyte imbalance – can affect the heart and muscles
- poor weight gain and growth faltering
Long-term outlook
With the right care, most babies recover fully from persistent diarrhoea. Identifying the cause early – whether it is an infection, allergy, or digestion problem – can help your baby get back to good health and normal growth.
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Always verify with your doctor
Health guidelines vary by country and region. The information in this article is based on international clinical guidelines but may not reflect the specific guidelines, medications, or practices in your country. Always discuss your health concerns with your own doctor or healthcare provider, and refer to your local national health guidelines where available.
Important notice This information is for educational purposes only. It does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider about your specific situation. If you are experiencing a medical emergency, call your local emergency services immediately.
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Sources and guidance
This article is educational and is prepared with reference to recognized health information and clinical guidance sources where available. Specific source links may vary by topic.
Last updated: July 20, 2026
Educational note: This information is for education only and is not a diagnosis.
Use it to support, not replace, advice from a licensed clinician.
If symptoms are severe, worsening, or urgent, call your local emergency number or seek emergency care.