Lactose Intolerance

What is lactose intolerance?

Lactose intolerance happens when your body struggles to break down lactose - a type of sugar found in milk and dairy products. When you eat or drink something with lactose, it can cause uncomfortable symptoms in your tummy and elsewhere in your body.

What symptoms might you notice?

Symptoms can start anywhere from a few minutes to a few hours after having dairy products. Common signs include:

Tummy problems:

• Tummy pain or feeling uncomfortable
• Feeling bloated
• Passing wind more than usual
• Rumbling noises from your tummy
• Loose poo or constipation
• Feeling sick or being sick

Other symptoms:

• Headaches
• Feeling very tired
• Aches in your joints or muscles

Which foods contain lactose?

Lactose is found in dairy products made from animal milk, including cow's, goat's, and sheep's milk. This includes:

• Milk
• Butter
• Cheese
• Cream
• Yoghurt
• Ice cream

Many processed foods also contain lactose, such as:

• Breakfast cereals
• Bread, crackers, cakes, and biscuits
• Sauces and salad dressings
• Diet and protein shakes

Always check food labels carefully if you think you might be lactose intolerant.

When should you speak to your GP?

See your GP if:

• Your symptoms keep coming back and often happen after eating
• You've noticed changes in your poo that aren't normal for you
• You've had loose poo, been going more often, or been constipated for 3 weeks
• You've had blood in your poo for 3 weeks
• You've had tummy bloating for 3 weeks
• You've been losing weight without trying

Emergency warning signs

Call 999 immediately if you have:

• Sudden swelling of lips, mouth, throat, or tongue
• Very fast breathing or struggling to breathe
• Tight throat or trouble swallowing
• Blue, grey, or pale skin, tongue, or lips
• Sudden confusion, drowsiness, or dizziness
• Fainting and can't be woken up
• A swollen, raised, or itchy rash

These could be signs of a serious allergic reaction, which is different from lactose intolerance and needs emergency treatment.

How is lactose intolerance diagnosed?

Your GP might suggest:

• Trying a lactose-free diet to see if symptoms improve
• Blood tests
• A breath test that measures hydrogen gas to see how well you digest lactose
• In severe cases, a camera test called a gastroscopy

How can it be managed?

Most people can control their symptoms by:

• Eating smaller portions of dairy foods
• Avoiding dairy products completely
• Taking lactase supplements before eating dairy (these contain the enzyme your body needs)

Important: If you think your child might be lactose intolerant, speak to your GP before removing dairy from their diet, as children need calcium and other nutrients for healthy growth.

Sometimes lactose intolerance is caused by other conditions like coeliac disease or bowel infections. Treating the underlying cause can help.

Remember, lactose intolerance is different from a milk allergy, which can be life-threatening and needs urgent medical attention.

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Based on NHS.uk guidance. Written by Dr Krishnan Pasupathi, NHS GP.