How to Test for Lactose Intolerance

A man holds his mouth, looking sick, while holding a glass of milk.

What is Lactose Intolerance?

Lactose intolerance is a common digestive disorder that occurs when the body is unable to produce enough lactase.

This is the enzyme that you need to process lactose — the sugar found in milk and other dairy products.

Lactase is responsible for breaking lactose down into two simpler sugars, which are easier for the body to absorb into the bloodstream.

If lactose isn’t properly broken down and absorbed, it remains in the digestive system which can cause a number of uncomfortable symptoms.

How Do You Know if You’re Lactose Intolerant?

The symptoms of lactose intolerance can vary from person to person, depending on the severity of your condition.

Some people may only have mild symptoms while others will experience more severe digestive issues. The most common symptoms of lactose intolerance include:

  • Abdominal pain

  • Bloating

  • Gas

  • Nausea

  • Vomiting

  • Diarrhea

These symptoms typically appear within 30 minutes to two hours after consuming dairy products.

If you experience any of these symptoms after having dairy, it’s recommended to see your doctor to determine if you’re lactose intolerant.

A hand is seen getting a finger prick glucose blood test.

What are the Testing Methods That Determine Lactose Intolerance?

The best way to find out if you’re lactose intolerant is to take a professional medical test.

It’s important to get tested for lactose intolerance because it’s an essential step in helping you manage your symptoms.

The three most common lactose intolerance tests are:

  • Glucose blood test: This involves consuming a liquid containing lactose and then measuring the blood glucose levels over a two-hour period. If the levels in the blood samples do not increase, it may indicate that the body cannot digest lactose properly.

  • Hydrogen breath test: This test involves having a drink with a high amount of lactose and then measuring the amount of hydrogen in the breath over a period of time. If there is a low amount of hydrogen in the breath, it may indicate lactose tolerance, while a high amount signals intolerance.

  • Stool acidity test: This test is typically used for infants and young children who cannot complete the other tests. It involves analyzing the acidity of the stool after consuming lactose. If the stool is acidic, it may indicate that the lactose is not properly digested and that some level of intolerance is present.

A lactose intolerance test is typically performed in a lab or medical facility, and it is important to follow any instructions while they are administering the test.

Can You Test for Lactose Intolerance at Home?

There are a number of at-home testing kits available to help you determine if you’re lactose intolerant.

They usually involve the collection of a blood or urine sample that is sent to a laboratory for testing.

It’s important to note that these tests aren’t always as reliable as the ones carried out by healthcare professionals.

If you’re considering at-home tests, it’s important to speak to your healthcare provider first to make sure that the kit is appropriate for your individual needs.

You should also keep in mind that a positive result from an at-home test doesn’t necessarily mean that you are lactose intolerant. Further testing may be necessary to confirm your diagnosis.

What are the Risks of Lactose Intolerance Tests?

Lactose intolerance tests usually don’t cause complications or pose any risks when taking them.

If you are lactose intolerant, you may feel some cramps, bloating, or discomfort after the test.

This is completely normal and happens because you’ve consumed a drink with a high amount of lactose. The feeling should subside after a few hours.

You may also experience a bit of pain or bruising at the site where blood was drawn for the test.

Should You See a Doctor about Lactose Intolerance?

If you have undergone testing for lactose intolerance and received a positive result, it is important to follow up with a healthcare professional.

Not only can they professionally diagnose lactose intolerance, but they can also help you manage your symptoms and suggest dietary changes or medications to improve digestion.

It is also important to see your doctor if you experience any lactose intolerance symptoms after consuming dairy.

Persistent symptoms can indicate other health conditions like digestive and kidney diseases. A healthcare professional can help determine the appropriate course of treatment.

A glass of nut milk, lactose free.

Where Can You Learn More About Lactose Intolerance and Similar Conditions?

If you suspect that you are lactose intolerant or want to know more about testing, you can speak to a board-certified physician or nurse from the comfort of your home.

Head over to LifeMD to schedule a telehealth appointment.


Teena Harrison, DNP, FNP-BC

Teena graduated with a Master of Science Degree from Barry University in Miami Shores, Florida and earned her Doctoral Degree from Touro University in Henderson, NV. Teena has been practicing for 25 years in various healthcare arenas including Family Practice, Urgent Care, and Geriatrics. She is board certified in Family Medicine. Teena is a devoted and compassionate medical professional whose daily goal is to provide quality care while ensuring her patients feel truly listened to and at ease during their time with her. She believes in treating the whole person — not just the diagnosis — and is committed to actively involving her patients in the development of their treatment plan. Teena currently lives in Winston Salem, NC with her dog Nacho Cheese and enjoys spending time with her children and grandchildren. She is also a member of ASPCA and is involved in animal rescue.

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This article is intended for informational purposes only and should not be considered medical advice. Consult a healthcare professional or call a doctor in the case of a medical emergency.

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