Updated September 2026.
Lactose intolerance means you get digestive symptoms, such as bloating, gas and diarrhoea, after eating or drinking lactose, the natural sugar in milk. It happens when your small intestine does not make enough lactase, the enzyme that breaks lactose down. It is uncomfortable but not dangerous, and most people can manage it well by adjusting their diet.
This guide covers the symptoms, causes, how it is diagnosed, what to eat, how lactase supplements fit in, and when to see a doctor.
What is lactose intolerance?
To be absorbed, lactose must be split by lactase into two simpler sugars, glucose and galactose. When there is not enough lactase, some lactose passes undigested into the large intestine. There, gut bacteria ferment it, producing gas, and the undigested sugar can draw water into the bowel.
Doctors distinguish between two related terms:
- Lactose malabsorption: the small intestine cannot digest all the lactose you consume.
- Lactose intolerance: you have symptoms because of it. Not everyone with lactose malabsorption has symptoms.
Lactose malabsorption is very common. Experts estimate that it affects about 68 percent of the world’s population, although many of these people have no symptoms or only mild ones.
Symptoms of lactose intolerance
Common symptoms include:
- Bloating
- Gas
- Diarrhoea
- Stomach pain and cramps
- Nausea, and sometimes vomiting
- Rumbling sounds in the stomach
Symptoms usually start within a few minutes to a few hours of having lactose. How severe they are depends largely on how much lactose you had and how much lactase your body still makes. Many people can handle small amounts without trouble.
Lactose intolerance or milk allergy?
They are often confused, but they are different conditions:
- Lactose intolerance is a digestive problem with milk sugar. It causes discomfort but is not dangerous.
- Milk allergy is an immune reaction to milk proteins. Reactions can be immediate and severe, with hives, swelling of the face or lips, or difficulty breathing, and can be life-threatening.
If you ever have swelling, wheezing or difficulty breathing after dairy, seek emergency medical help. Lactase supplements do not help with milk allergy.
Causes and types
Primary lactose intolerance (lactase non-persistence)
This is the most common type. The small intestine makes less lactase after infancy, and levels fall further with age. Symptoms may appear in later childhood, the teenage years or adulthood. It is more common in people of African, Asian, Hispanic and American Indian descent.
Secondary lactose intolerance
Infections, illnesses or surgery that injure the small intestine can reduce lactase production. Examples include intestinal infections, coeliac disease, bacterial overgrowth and Crohn’s disease, as well as some cancer treatments. If the underlying cause is treated, you may be able to tolerate lactose again.
Congenital lactase deficiency
A rare condition in which the small intestine makes little or no lactase from birth. It needs specialist medical care from the start.
Developmental lactase deficiency
In premature babies, the small intestine may not make enough lactase for a short time after birth. Lactase levels usually rise as the baby grows.
How lactose intolerance is diagnosed
A doctor will usually start with your symptoms, eating habits, and family and medical history, and may examine your abdomen. Common next steps are:
- A trial without lactose: you avoid milk and milk products for a period to see whether symptoms improve, then reintroduce them.
- Hydrogen breath test: you drink a liquid containing a measured amount of lactose, and your breath is tested at intervals over a few hours. Rising hydrogen levels together with symptoms point to lactose intolerance.
- Tests for other conditions: symptoms can overlap with irritable bowel syndrome, coeliac disease, inflammatory bowel disease and small intestinal bacterial overgrowth, so your doctor may check for these.
Try not to diagnose yourself by cutting out dairy long term without advice, especially for children. A doctor or dietitian can confirm the cause and make sure your diet stays balanced.
Managing your diet
There is no treatment that increases the amount of lactase your body makes in primary or congenital lactose intolerance. Instead, most people manage their symptoms by finding how much lactose they can comfortably handle.
Find your personal limit
Research suggests that many people with lactose intolerance can have about 12 grams of lactose, roughly the amount in one cup of milk, with no symptoms or only mild ones. Practical tips:
- Have small amounts of milk with a meal rather than on its own.
- Reintroduce dairy gradually to see what you tolerate.
- Try yogurt and hard cheeses such as cheddar or Swiss, which many people find easier.
- Use lactose-free milk and dairy products.
Lactose in common foods
| Food | Lactose level | Notes |
|---|---|---|
| Fresh milk and cream | Higher | One cup of milk contains about 12 g of lactose |
| Ice cream | Higher | A scoop contains an amount similar to a cup of milk |
| Yogurt | Often better tolerated | Many people with lactose intolerance can manage it |
| Hard cheeses (cheddar, Swiss, parmesan) | Lower | Small amounts are often tolerated |
| Lactose-free milk and dairy | Very low | Made for people with lactose intolerance |
| Processed foods (bread, cereals, soups, processed meats, coffee creamers) | Varies | May contain hidden lactose; check the label |
Individual tolerance varies, so use this as a starting point rather than a strict rule.
Watch for hidden lactose
Lactose can appear in foods you would not expect. On ingredient lists, look for:
- Milk, lactose, whey and curds
- Milk by-products
- Dry milk solids and non-fat dry milk powder
Protect your calcium and vitamin D
Cutting back on dairy can make it harder to get enough calcium and vitamin D, which are important for bone health. Good non-dairy sources include:
- Calcium: canned salmon or sardines with soft bones, broccoli and leafy greens, oranges, almonds, dried beans, tofu, and fortified cereals, juices and soy drinks
- Vitamin D: eggs, oily fish such as salmon, fortified cereals and juices, and safe sunlight exposure
A dietitian can help you plan meals if you are cutting out a lot of dairy.
Lactase supplements
Lactase products contain the enzyme your body is short of. They come as tablets taken just before a meal or drink that contains dairy, or as drops added to milk; some enzyme supplements come as capsules. They help break down lactose and can reduce symptoms for some people. They do not change how much lactase your body makes, so you need them each time you have lactose.
Check with your doctor before using lactase products if you are pregnant or breastfeeding, or for a young child.
Goodness Digestive Enzymes and lactose
Goodness Digestive Enzymes is a food supplement that contains lactase, providing 1,000 ALU of lactase activity per capsule, to help break down lactose from milk and dairy foods. It also contains 12 other enzymes that help digest proteins, carbohydrates, fats and plant fibres, which may suit people whose meals combine dairy with other foods.
- How to use: for adults, 1 to 2 capsules before meals, or as directed by your healthcare provider.
- Where to find it: registered as a food supplement with the Jordan Food and Drug Administration and available in pharmacies in Jordan and Saudi Arabia. Ask your pharmacist whether it is right for you.
If it is not available near you, you can also order it online. To understand how enzymes differ from probiotics and prebiotics, read our guide to probiotics, prebiotics and digestive enzymes.
When to see a doctor
See a doctor if:
- You often get symptoms after eating dairy
- You are worried you are not getting enough calcium
- Your bowel habits change and the change lasts three weeks or more
- You lose weight without trying
- You notice blood in your stool
- You are thinking of removing dairy from your child’s diet
- You have signs of an allergic reaction, such as swelling or difficulty breathing (seek emergency help)
Frequently asked questions
Can lactose intolerance develop in adulthood?
Yes. In the most common type, lactase levels fall gradually after infancy, so symptoms may first appear in the teenage years or adulthood. Illness or injury to the small intestine can also cause it at any age.
Is lactose intolerance permanent?
Primary lactose intolerance is usually lifelong. Secondary lactose intolerance may improve once the underlying cause is treated.
Do I have to give up dairy completely?
Usually not. Many people tolerate small amounts, especially with meals, and often find yogurt, hard cheeses and lactose-free products easier.
How soon after dairy do symptoms start?
Usually within a few minutes to a few hours after having lactose.
Can I use a lactase supplement for milk allergy?
No. Milk allergy is an immune reaction to milk proteins, and lactase does not affect it. People with milk allergy need medical advice on avoiding milk.
Can children take lactase supplements?
Talk to your doctor or pharmacist first. Goodness Digestive Enzymes is intended for adults.
Sources
- NIDDK: Definition and Facts for Lactose Intolerance
- NIDDK: Symptoms and Causes of Lactose Intolerance
- NIDDK: Diagnosis of Lactose Intolerance
- NIDDK: Eating, Diet and Nutrition for Lactose Intolerance
- NIDDK: Treatment for Lactose Intolerance
- NHS: Lactose intolerance
- Mayo Clinic: Lactose intolerance – Symptoms and causes
- Cleveland Clinic: Lactose Intolerance – Symptoms, Diagnostic Tests and Treatment
