There is no cure for lactose intolerance, but most people are able to control their symptoms by making changes to their diet.

Some cases of lactose intolerance, such as those caused by gastroenteritis, are only temporary and will improve within a few days or weeks. Other cases, such as those caused by an inherited genetic fault or a long-term underlying condition, are likely to be lifelong.

Changing your diet

In most cases, cutting down on or avoiding sources of lactose and replacing them with lactose-free alternatives is enough to control the symptoms of lactose intolerance.

The exact changes you need to make to your diet depend on how sensitive you are to lactose. Some people are able to tolerate some lactose in their diet without any problems, whereas others experience symptoms after consuming food containing only a very small amount of lactose.

If you decide to experiment with what you can and can't eat, make sure that you introduce new foods gradually, rather than all at once. This will help you to get used to any foods that you might be sensitive to and identify any that cause problems.

Eating fewer products containing lactose, or avoiding them completely, can mean you miss out on certain vitamins and minerals in your diet and increase your risk of complications of lactose intolerance. You will therefore also need to make sure you are getting enough nutrition from either lacto-free foods or dietary supplements.

If you or your child are extremely sensitive to lactose, talk to your GP about your diet. You may need to have regular bone mineral density checks, or you may be referred to a dietitian (an expert in diet and nutrition). They can advise you about what foods should be included in your, or your child’s, diet.

Sources of lactose

Some of the main sources of lactose you may need to cut down on or avoid if you are lactose intolerant are described below.

Milk

A major source of lactose is milk, including cow's milk, goat's milk and sheep's milk. Depending on how mild or severe your lactose intolerance is, you may need to change the amount of milk in your diet.

For example:

• you may be able to have milk in your tea or coffee, but not on your cereal
• some products containing milk, such as milk chocolate, may still be acceptable in small quantities
• you may find that drinking milk as part of a meal, rather than on its own, improves how the lactose is absorbed

If even a small amount of milk triggers your symptoms, there are some alternatives that you can try, such as soya or rice milk (see below).

Dairy products

Other dairy products made from milk, such as butter, ice cream and cheese, can also contain high levels of lactose and may need to be avoided if you are lactose intolerant.

Some dairy products however, such as hard cheese and yoghurt, contain lower levels of lactose than milk and other products, so you may still be able to have them.

It's worth experimenting with different foods to try to find out if there are any dairy products you can eat because they are a good source of essential nutrients such as calcium.

Other foods and drinks

As well as milk and dairy products, there are other food and drinks that can sometimes contain lactose.

These can include:

• salad cream, salad dressing and mayonnaise
• biscuits
• chocolate
• boiled sweets
• cakes
• some types of bread and other baked goods
• some breakfast cereals
• packets of mixes to make pancakes and biscuits
• packets of instant potatoes and instant soup
• some processed meats, such as sliced ham

Check the ingredients of all food and drink products carefully, because milk or lactose are often hidden ingredients.

The lactose found in some foods will not necessarily be listed separately on the food label, so you need to check the ingredients list for milk, whey, curds and milk products such as cheese, butter, cream.

Some ingredients may sound like they contain lactose when they don't, such as lactic acid, sodium lactate and cocoa butter. These ingredients don't need to be avoided if you are lactose intolerant.

Medication

Some prescription medicines, over-the-counter medicines and complementary medicines may contain a small amount of lactose. While this is not usually enough to trigger the symptoms of lactose intolerance in most people, it may cause problems if your intolerance is severe or you are taking several different medicines.

If you need to start taking a new medication, check with your GP or pharmacist in case it contains lactose.

Lactose-free foods and drinks

There are a number of alternative foods and drinks available in supermarkets to replace the milk and dairy products you need to avoid.

Food and drinks that don't usually contain lactose include:

• soya milks, yoghurts and some cheeses
• milks made from rice, oats, quinoa, almonds, hazelnuts, coconut and potato
• foods which carry the 'dairy-free' or 'suitable for vegans' signs
• carob bars

You can also buy cow's milk containing additional lactase (the enzyme used to digest lactose). This means you still get the nutritional benefits of the milk, but you are less likely to experience any symptoms after consuming it.

Getting enough calcium

If you are unable to eat most dairy products, you may not be getting enough calcium in your daily diet. Calcium has several important functions, including helping build strong bones and teeth, regulating muscle contractions (including heartbeat) and ensuring blood clots normally.

Therefore, it's a good idea to choose lactose-free products with added calcium and ensure your diet contains alternative sources of calcium, such as:

• green leafy vegetables, such as broccoli, cabbage and okra
• soya beans
• tofu
• nuts
• bread and anything made with fortified flour
• fish containing edible bones (for example, sardines, salmon, and pilchards)

You can also buy combined calcium and vitamin D supplements from most pharmacists to help maintain good bone health.

It is important to check with your GP or dietitian whether you should be taking supplements, however, as taking excessively high levels of calcium can cause side effects.

Lactase substitutes

In addition to dietary changes, you may also find it useful to take liquid drops, tablets or capsules that contain lactase substitutes. These are available from most health foods shops.

Lactase substitutes replace the lactase your small intestine is not producing, which can reduce your symptoms by helping your body break down any lactose in your diet more easily.

Lactase substitutes can either be added to milk or taken just before eating a meal containing lactose.

Lactose intolerance in children

If your child is lactose intolerant, they may be able to consume small amounts of lactose without experiencing symptoms. This is quite safe, but you may need to experiment to find out how much they can comfortably eat or drink.

If your child is unable to tolerate any lactose, your doctor may refer you to a dietitian for nutritional advice because it is important young children have certain nutrients in their diet to ensure healthy growth and development.

In general, the same rules about foods to try or to avoid are similar for children and adults (see above).

For babies with lactose intolerance, lactose-free formula milk is available to buy from pharmacies and supermarkets, although soya formula is not recommended for children under six months because  it contains hormones that may interfere with your baby’s future physical and sexual development.

Breastfed babies may benefit from lactase substitute drops to help their bodies digest the lactose in breast milk.

For many children, lactose intolerance is only temporary and will improve after a few weeks, after which point it is safe to gradually reintroduce milk and dairy products into their diet.