Lactose is a type of sugar found in milk and milk products. Lactose intolerance happens when a person eats or drinks more lactose than their body can digest. It is not caused by an allergy to milk. The symptoms of lactose intolerance most commonly include stomach pain and diarrhoea.

Lactose intolerance occurs when the body doesn’t have enough of the enzyme (chemical) called lactase, which helps digest lactose. A temporary lactose intolerance can happen after some illnesses, such as gastroenteritis, when the body's stores of lactase are temporarily reduced. Inflammation of the bowel as a result of intolerance to other foods, infection or bowel surgery can also result in lactose intolerance.

For children aged seven to 10 years, lactose intolerance is usually treated by avoiding products containing milk or lactose. Some children develop a permanent intolerance to lactose and have to avoid milk products for the rest of their lives.

Signs and symptoms of lactose intolerance

If your child has lactose intolerance, after consuming milk or milk products they are likely to have: 

• stomach pain or bloating
• diarrhoea
• wind.

Lactose intolerance is very rare in babies. However, if your baby displays unsettled behaviour, poor growth, loose bowel actions and significant nappy rash, this may indicate a lactose intolerance. 

When to see a doctor

If your child has symptoms of lactose intolerance, take them to see a GP. The doctor will be able to determine if your child is lactose intolerant and rule out other conditions. They may do some investigations and recommend that you see a dietician. It is important not to self-diagnose your child and make changes to their diet without consulting a doctor or dietitian.

A low lactose diet

If your child is found to be lactose intolerant, a low lactose diet will be recommended for a few weeks. This means reducing their intake of products that have milk or lactose in them. These include products containing:

• milk
• skim milk powder
• non-fat milk solids
• yoghurt
• milk protein
• milk solids.

Read ingredient labels on commercial products carefully. Check with your doctor or pharmacist whether any medication your child is prescribed contains lactose.

If your child does consume some lactose there is no need for concern – children with lactose intolerance will usually be able to tolerate small amounts of lactose; however, large amounts of lactose often produce symptoms.

Low lactose diets for children

Select appropriate foods from each of the following groups each day for a nutritious, low lactose diet.

Milk and milk products

• Avoid milk, yoghurt, cream, ice-cream or milk desserts containing lactose. Also avoid cream cheese, processed cheese, cheese spread, cottage cheese and ricotta cheese.
• All other cheeses, including hard cheeses such as cheddar and parmesan, contain a low amount of lactose and are usually well tolerated.
• Milk is a very important source of calcium, protein and vitamins in a child's diet. There are a number of low lactose milks available in the long-life section or dairy cabinet in most supermarkets. Calcium-fortified soy milk is also lactose-free.
• Use lactose-free milk in place of regular milk for cereals, custards and sauces.
• Low lactose yoghurt, cream and sour cream are now available.
• Low lactose and soy-based yoghurts are also available in most large supermarkets, and come in a variety of flavours.

For young children, aim for two to three serves of low lactose dairy products or lactose-free milk each day. For older children, aim for three serves of low lactose dairy products or lactose-free milk each day. Teenagers should aim for four serves of low lactose dairy products or lactose-free milk each day.

Breads, cereals, rice and pasta

• These provide energy, B vitamins and fibre. Check labels on breakfast cereal packets and avoid those containing milk or lactose.

Fruit and vegetables (fresh, frozen, tinned or dried)

• These provide energy, vitamins, minerals and fibre. Avoid instant mashed potato and vegetables with added milk, white or cheese sauces.

Meat and protein foods (including fish, chicken, pulses and legumes)

• These provide protein and minerals and are safe for children on low lactose diets. 

Fats and oils

• Butter, margarine and oil provide energy and some vitamins. They are low in lactose and are usually tolerated in small amounts.

Other foods

• Other foods that may contain lactose include milk chocolate, chocolate-coated biscuits, creamed soups and cakes.

Lacteeze drops and tablets contain lactase, which breaks down lactose. The drops can be added to foods containing lactose, making the food lactose-free, while the tablets can be taken before eating foods with lactose in them as the lactase will help with the digestion of lactose. You can buy Lacteeze online or from pharmacies.

Low lactose diets for infants

If your baby is diagnosed with lactose intolerance, an infant formula product that is low in lactose may be recommended. Soy formula is not recommended for infants younger than six months old.

If you are breastfeeding your baby, even if you reduce lactose in your own diet, lactose will still be present in your breastmilk. You can speak to a lactation consultant about adjusting breastfeeding to reduce the amount of lactose passed through to your baby. Your doctor may recommend giving your baby Lacteeze during feeding – discuss how this can be done with your doctor. 

Follow-up

After the low lactose diet, a normal diet containing lactose can usually be reintroduced in consultation with your child's doctor or dietitian. This needs to be done slowly and under supervision, over the course of a week or longer.

Key points to remember

• Only change to a low lactose or lactose free diet in consultation with your child's doctor or dietitian.
• Read ingredient labels on food products carefully to avoid ingredients that contain large amounts of milk or lactose.
• Check with your doctor or pharmacist whether any medications your child is using contain lactose.
• Small amounts of lactose are usually well tolerated. Large amounts of lactose usually produce symptoms.
• Discuss with your child's doctor or dietitian the reintroduction of foods containing lactose.

For more information

• The Australian Government's Health Direct website: Lactose intolerance treatments
• Better Health Channel: Lactose intolerance
  
• See your GP or dietician.

Developed by The Royal Children's Hospital Gastroenterology and Nutrition and Food Services departments. We acknowledge the input of RCH consumers and carers.

Reviewed May 2018.

This information is awaiting routine review. Please always seek the most recent advice from a registered and practising clinician.

Kids Health Info is supported by The Royal Children’s Hospital Foundation. To donate, visit www.rchfoundation.org.au.