Baby Diarrhoea: Causes, Symptoms & When to See a GP

Baby diarrhoea is common and usually not serious, but it may be worrying, especially if your little one seems unsettled or you're unsure what’s normal. If your baby has diarrhoea, you’ll likely notice frequent, watery poos that differ from their usual bowel movements. Most cases are caused by a virus and clear up within a few days, but keeping your baby hydrated and knowing when to call your GP is important.

This guide covers everything you need to know about diarrhoea in babies, from causes and symptoms, to treatment, prevention and when to seek help – including what to do if your baby has diarrhoea but seems fine otherwise.

What Is Baby Diarrhoea?

Baby poo comes in all sorts of colours and consistencies. Baby diarrhoea is the name for a discharge of runny or watery poo, often several times a day. In babies and young children, it’s often caused by a viral infection such as norovirus or rotavirus.

Since diarrhoea in babies is usually caused by germs that affect the stomach, it may be accompanied by vomiting. Diarrhoea happens when the digestive system becomes overstimulated due to some irritation, for example, a viral or bacterial infection. When this happens, waste passes through the intestines so quickly that the bowel doesn’t have time to absorb the water it contains.

Diarrhoea usually stops in a few days with home care and treatment, but it may easily lead to dehydration, so it’s important to keep up your child’s fluid intake. See a doctor if your baby has diarrhoea. Young babies may become dehydrated more easily than older children, especially under the age of 6 months.

Infant and Baby Diarrhoea Signs and Symptoms

Diarrhoea in babies typically means very loose or watery stools that occur more often than usual. If your baby has diarrhoea but seems otherwise fine, it may simply be a mild case. Common signs and symptoms that may accompany diarrhoea in babies include:

• A high temperature or fever

• Nausea (your older toddler may be able to tell you they feel sick)

• Vomiting — this is particularly common if your child has gastroenteritis

• Not wanting to eat or take a feed

• Headache (your toddler may say their head hurts)

• Tummy ache or abdominal pain (your toddler may tell you their tummy hurts)

• An urgent need to poo (again, your toddler may be able to express this)

• Signs of dehydration, such as fewer wet nappies, dry mouth, sunken eyes, drowsiness, or tearless crying.

Causes of Baby Diarrhoea

In newborn babies, toddlers and young children, diarrhoea is usually caused by viruses such as norovirus or rotavirus. 

Other possible causes of diarrhoea in babies include:

• Food poisoning

• Bacterial infection

• Food intolerance or allergy

• Some medicines you might give your child

• A parasite

• Coeliac disease or inflammatory bowel disease.

Treatment of Infant Diarrhoea

The kind of treatment your baby’s GP recommends will depend on their diagnosis of what is causing the diarrhoea in the first place and how severe it is.

There is no medication for diarrhoea in babies that is triggered by a virus, which is the most common cause of diarrhoea. Diarrhoea caused by a virus tends to clear up on its own with time. With diarrhoea – besides keeping your little one comfortable and treating other symptoms like fever or tummy ache – it’s important to keep your child hydrated.

In some cases, your child's GP may want to run tests, for example by sending a stool sample to a laboratory to find out what kind of virus or bacteria is causing the illness.

If the doctor suspects that your baby’s diarrhoea has a cause other than a viral or bacterial infection, they may conduct further tests or refer your child to a specialist who can investigate the causes and recommend suitable treatment.

Treatment of Severe Diarrhoea

If your baby has diarrhoea and is showing signs of dehydration, refusing feeds, vomiting repeatedly or has blood or mucus in their poo, they need urgent medical care.

In severe cases, your doctor might recommend oral rehydration solutions (ORS) to replace lost fluids and salts. If your little one can’t keep fluids down or shows signs of serious dehydration, they may need fluids through a drip in the hospital.

If a Food Allergy Is Suspected

If you or your GP suspect that your baby’s diarrhoea may be linked to a food allergy or intolerance, you may be referred to an allergy clinic. There, your little one might undergo skin prick tests, blood tests or be placed on an elimination diet. This involves removing suspected foods from their diet for a short period to see if symptoms improve.

It’s important not to eliminate foods without guidance. Always consult your child’s GP or a qualified dietician before cutting out any major food groups. Your baby needs a balanced diet to support healthy growth and development, even while investigating possible allergies.

Medicine for Diarrhoea in Babies

If you’re wondering what to give babies for diarrhoea, keep in mind that over-the-counter anti-diarrhoea medicines are not recommended for children under the age of 12 years old. Check with your child's doctor before giving your little one any medication for diarrhoea.

In some cases, medicine could be prescribed or recommended to treat or ease the other symptoms of an illness that’s causing the diarrhoea. For example, your GP may recommend a medicine suitable for your baby to relieve tummy pain and discomfort and/or help bring down a fever.

Keeping Your Child Hydrated

Keeping your baby or toddler hydrated during a spell of baby diarrhoea is essential, as dehydration may happen quickly, especially in babies under 6 months. The best way to support hydration depends on how your child is currently being fed. 

Here are some tips for keeping your little one hydrated during diarrhoea:

• If you are breastfeeding, continue to offer feeds as it may help to give smaller amounts more frequently.

• If your baby is formula-fed, offer extra small sips of cooled boiled water between feeds. Always make up the formula as directed – do not dilute it with additional water.

• If your little one is on solid foods, stick to their usual diet and offer frequent small sips of water throughout the day. If your older child doesn’t feel like eating, don’t worry – just keeping up on fluids is more important.

• Avoid fruit juices or fizzy drinks, as these can make the diarrhoea worse.

• Your doctor may recommend an oral rehydration solution (ORS) to help replace fluids, sugars and salts lost due to diarrhoea. Always use as directed by your GP or pharmacist.

If your baby has diarrhoea but seems otherwise fine, still keep a close eye on their fluid intake and nappy output to help prevent dehydration.

When to See the Doctor

Babies and toddlers may become dehydrated more quickly than older children, particularly those under 6 months old, so it’s a good idea to consult your GP if your baby or toddler under 5 years old has diarrhoea, even if it seems mild.

Call your GP or 111 straight away if:

• Your baby has diarrhoea and is under 1 year old

• Your child has diarrhoea six or more times in 24 hours

• Your baby stops breastfeeding or bottle feeding

• Your baby has a fever

• The diarrhoea is accompanied by vomiting

• You notice blood in your baby’s poo

• The diarrhoea lasts longer than seven days

• You see signs of dehydration, including:

  • Fewer wet nappies or no wet nappies

  • Dark or strong-smelling pee

  • Dry mouth

  • Sunken eyes

  • No tears when crying

  • A sunken fontanelle (the soft spot on top of your baby’s head).

Call 999 or go to A&E immediately if your child:

• Is difficult to rouse, floppy or unresponsive

• Has trouble breathing

• Might have swallowed something poisonous

• Vomits blood or what looks like coffee grounds

• Has sudden, severe or constant tummy pain

• Has green or yellowy-green vomit

• Has a stiff neck or shows signs of pain when looking at bright lights.

Preventing Diarrhoea

Diarrhoea in babies can’t always be prevented completely, but there are ways to lower the risk, especially when it comes to viral infections, bacteria and food poisoning.

Check that your child is up to date with the rotavirus vaccine, which may guard your little one against this specific virus. This vaccine is given in the form of liquid drops for your baby to swallow, not as an injection. Talk to your health visitor if you have any questions about the rotavirus vaccine.

• Keep up with the rotavirus vaccine. Given orally at 8 weeks and 12 weeks, it protects against a common cause of diarrhoea. 

• Wash your baby’s hands regularly. Use wipes if water isn’t available.

• Avoid giving food or drink on the potty to reduce germ spread.

• Teach toddlers to wash their hands properly after using the toilet or touching pets.

These simple habits may help prevent baby diarrhoea, especially from viral or hygiene-related causes.

Food safety

Food poisoning is a common cause of diarrhoea in babies and older children. By following good food hygiene practices, you may lower the risk of diarrhoea caused by bacteria or parasites in food.

Good food safety habits include:

• Washing hands before and after handling food, especially after touching raw meat, fish, shellfish, eggs or vegetables

• Keeping food prep areas clean and pets away from surfaces

• Washing bowls,cutlery and chopping boards in hot soapy water or in the dishwasher

• Cleaningkitchen surfaces thoroughly after handling raw meat, especially poultry

• Storing raw meats and eggs separately in sealed containers at the bottom of the fridge

• Cooking food all the way through, then allowing it to cool safely before serving

• Not keeping or reusing half-eaten baby food

• Only give lightly cooked or raw egg dishes if the eggs have the ‘red lion’ stamp; otherwise, cook until both yolk and white are firm

• Ensuring that shellfish or seafood is thoroughly cooked

• Avoiding unpasteurised milk, which may contain harmful bacteria

• Wash and peeling fruit and veggies before offering to your baby or toddler

• Refrigerating meat promptly after shopping

• Cooling leftovers within 1–2 hours and storing in the fridge or freezer. Rice must be cooled quickly (within 1 hour), stored for no longer than 24 hours, and never reheated more than once.

These steps may help reduce the risk of baby diarrhoea linked to contaminated or improperly handled food.

How to Stop Diarrhoea from Spreading

The germs that can cause diarrhoea in babies are often infectious, so it’s important to take steps to prevent the diarrhoea from spreading. 

Here are some ways to lower the risk of diarrhoea making other people ill:

• Wash your and your child’s hands carefully with soap and warm water after using the toilet and before eating or making food

• Clean the toilet (including the seat and handle) or potty with disinfectant after every bout of diarrhoea

• Wash any soiled clothing and bedclothes separately from other clothes at the highest temperature possible for the given fabric (check the label if you’re unsure) 

• Don’t share towels, flannels, plates, cups, other crockery or utensils

• Keep your little one home from nursery, preschool or other group activities until at least 48 hours after the last watery stool.

The Bottom Line

Although there’s plenty you can do to lower the risk of diarrhoea in your baby, the infections that cause it are very common so sooner or later you may encounter some runny poo in your baby’s nappy despite your best efforts.

While diarrhoea is uncomfortable for your baby and it can be worrying for you (and sometimes unpleasant to clean up the mess), it usually only lasts a few days. In the meantime, check in with your child’s doctor and take extra care to keep your child hydrated and to prevent the diarrhoea from spreading. Before you know it your little one will be back to their old self again.

_{How We Wrote This Article The information in this article is based on expert advice found in trusted medical and government sources, such as the National Health Service (NHS). You can find a full list of sources used for this article below. The content on this page should not replace professional medical advice. Always consult medical professionals for full diagnosis and treatment.}