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Lactose Intolerance


What Is Lactose Intolerance?

Lactose intolerance is the inability to digest a sugar called lactose that is found in milk and dairy products.

Normally when a person eats something containing lactose, an enzyme in the small intestine called lactase breaks it down into simpler sugar forms called glucose and galactose. These simple sugars are then easily absorbed into the bloodstream and turned into energy — fuel for our bodies.

People with lactose intolerance do not produce enough of the lactase enzyme to break down lactose. Instead, undigested lactose sits in the gut and gets broken down by bacteria, causing gas, bloating, stomach cramps, and diarrhea.

Lactose intolerance is fairly common and seems to affect guys and girls equally. Little kids are less likely to have it, but many people eventually become lactose intolerant in adulthood — some while they are still teens. Some health care providers view lactose intolerance as a normal human condition and therefore don't really consider it a disease.

Who Gets Lactose Intolerance?

A person may be or may become lactose intolerant for different reasons:

What Happens When Someone Has It?

People with lactose intolerance may have a variety of symptoms. It all depends on how much dairy or how many milk-containing foods the person eats and how little lactase the body produces.

Usually within 30 minutes to 2 hours after eating, someone with lactose intolerance will experience nausea, stomach cramps, bloating, gas, and diarrhea. This can be unpleasant, not to mention embarrassing if you're at school or out with friends.

Because many people may think they're lactose intolerant when they really aren't, it helps to see a doctor who can diagnose the condition correctly and advise you on ways to manage it.

How Do Doctors Diagnose It?

If your doctor thinks you might be lactose intolerant, he or she will take your medical history by asking about any concerns and symptoms you have, your past health, your family's health, any medications you're taking, any allergies you may have, and other issues. Your doctor will also do a physical exam.

Doctors can test for lactose intolerance by using the hydrogen breath test. Normally very little hydrogen gas is detectable in the breath. However, undigested lactose in the colon ferments (breaks down) and produces various gases, including hydrogen.

If your doctor decides to give you a hydrogen breath test, you'll be asked to blow into a tube for a beginning sample. You'll then swallow a drink with lactose in it, wait a while, and breathe into the tube again. You'll be asked to blow into the tube every half hour for 2 hours in order to measure hydrogen levels in your breath. The levels should go up over time if you have lactose intolerance.

Doctors also can find out if you're able to digest lactose by testing for the presence of lactase with an endoscopy. During this procedure, doctors view the inside of the intestines by inserting a long tube with a light and a tiny camera on the end into the mouth.

A doctor can then take tissue samples and pictures of the inside of your gut and look for clues to why you've been having problems with what you're eating. The amount of lactase enzyme can be measured in one of these tissue samples.

Living With Lactose Intolerance

Lactose usually can be easily managed if you're in tune with your body. Everyone's different, but most people with lactose intolerance can eat a small amount of dairy. The trick is to eat dairy products in combination with other foods that don't contain lactose and not to eat too much dairy at once. It can also help to keep a food diary to learn which foods your body can or can't tolerate.

Dairy foods are the best source of calcium, a mineral that's important for bone growth. Because growing teens need about 1,300 milligrams (mg) of calcium each day, experts recommend that even teens who have lactose intolerance continue to include some dairy in their diet.

Foods like cheese or yogurt may be easier to digest than milk, so try a cup of yogurt for dessert or add a piece of cheese to your sandwich. Lactose-free milk is also a great way to get calcium in your diet without the problems that can come with lactose.

Taking a lactase enzyme supplement might help too. Taking this before eating foods that contain dairy will help the body digest the lactose sugar in dairy so you don't develop the symptoms of lactose intolerance, like pain, cramping, bloating, gas, and diarrhea.

Teens with the most severe symptoms of lactose intolerance might have to avoid all dairy products. It's extra important that these teens find other good calcium sources, so talking to a registered dietitian is a good idea. Dietitians are trained in nutrition and they can help people who are lactose intolerant come up with eating alternatives and develop a well-balanced diet that provides lots of calcium for developing strong bones.

Here are some tips for dealing with lactose intolerance:

Date reviewed: January 2015


Note: All information on TeensHealth® is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.

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