4 Early Symptoms Of Lactose Intolerance You Should Know

Consuming milk and dairy products has several benefits as they contain vitamins, minerals, calcium, and protein which are beneficial for overall health.

But do you fall under the group of people who have problems digesting milk products? Or does your body not produce enough lactase enzymes, causing unwanted symptoms when you consume dairy?

If the answer to any above of the questions was a yes, then you might fall under lactose-intolerant people.

Keep on reading the article then as we share detailed information on what is lactose intolerance, the early symptoms of lactose intolerance, the causes of lactose intolerance1, and how it can be diagnosed.

1. What is Lactose Intolerance?

What is Lactose Intolerance?

Lactose intolerance also called lactose malabsorption2 is a condition where people are unable to digest milk and dairy products.

Lactose is a sugar found in milk, and people with lactose intolerance face difficulty in digesting milk sugar which ultimately causes stomach cramps and bloating.

Our small intestine produces lactase enzyme that helps to digest lactose, which then gets absorbed into our bodies.

However, if our small intestine doesn’t produce enough lactase enzyme3, then the undigested lactose goes into the large intestine causing digestive problems.

2. Are Lactose Intolerant and Allergic to Dairy Products the Same Thing?

People often get confused between lactose intolerance and milk allergy, but there is a big difference between these two.

The symptoms of milk allergy are usually noticed among infants, but symptoms of lactose intolerance are common among the elderly age groups as well.

Bloating and pain in the stomach are the common early symptoms of lactose intolerance 4whereas, symptoms of milk allergy are rashes on the skin and diarrhea.

Food for Thought |  Milk Allergy vs. Lactose Intolerance

3. What are the Causes of Lactose Intolerance?

People who are lactose intolerant have a problem with lactose digestion due to the reduction of lactase production by the small intestine. The undigested lactose then goes to the large intestine causing digestive system problems.

If people with lactose intolerance drink milk or consume dairy products, they can notice various early symptoms of lactose intolerance, as the small intestine produces less lactase enzyme.

Other causes of lactose intolerance can be the small intestine stopping making lactase after an injury or premature babies producing little lactase enzyme as their small intestine not being fully developed.

4. What are the Different Types of Lactose Intolerance?

Based on its causes, the symptoms of lactose intolerance are classified into different types:

4.1. Primary Lactose Intolerance

Primary lactose intolerance or lactase non-persistence is a type that is noticed among most adults.

People with primary lactose intolerance are born with enough lactase to digest lactose, however, as they age, their small intestine does not produce enough lactase to break lactose. The reduction of lactase production makes it difficult to digest milk products.

4.2. Secondary Lactose Intolerance

Secondary lactose intolerance can happen at any age. It usually happens if there is an injury in your small intestine or you are suffering from some underlying conditions such as Crohn’s disease or celiac disease, or are under some medications.

People with Crohn’s disease5 mostly suffer from lactose intolerance, as the disease affects their digestive tract, including the small intestine, making it difficult to digest lactose.

People with Crohn’s disease fear eating dairy foods to avoid early symptoms of lactose intolerance such as diarrhea and pain in the abdomen. Apart from Crohn’s disease, people with celiac disease also have a higher chance of suffering from lactose intolerance.

People with celiac disease are strictly advised to follow a gluten-free diet as excess consumption of gluten causes inflammation in the intestine and that increases the chance of developing lactose intolerance.6

Usually, the symptoms of secondary lactase deficiency are temporary, if only the underlying conditions are resolved.

4.3. Developmental Lactose Intolerance

Developmental lactose intolerance is a type that is noticed among premature babies. It is a temporary condition that improves gradually as the babies grow.

In this condition, as the small intestines of premature babies are not developed properly, they cannot tolerate lactose consumption.

4.4. Congenital Lactase Deficiency

Congenital lactase deficiency is a genetic disorder that is commonly noticed among infants.

In this disorder, the babies are lactose intolerant. The small intestine of the babies does not produce lactase or produces little lactase which makes it difficult to digest breast milk, resulting in malnutrition and severe diarrhea.

If the baby is affected with congenital lactase deficiency, then it is recommended to switch over to lactose-free dairy products.

5. What Are the Early Symptoms of Lactose Intolerance?

If people with lactose intolerance drink milk or eat dairy products, then the early symptoms of lactose intolerance are noticed within a few hours. The early symptoms of lactose intolerance can be of various types, depending on how much lactose the person has consumed.

So, some of the early symptoms of lactose intolerance are:

5.1. Gas Diarrhea

Diarrhea is a watery stool that happens more than usual and is one of the early symptoms of lactose intolerance.

If people with lactose intolerance consume foods that contain lactose, then the undigested lactose moves to the colon. The intestinal microflora then produces acids and gases through fermentation which disrupts the normal colon function and elevates the secretion of water from the body causing diarrhea.

5.2. Constipation

Constipation is a hard stool that happens less than usual, causing discomfort in the stomach and is also one of the early symptoms of lactose intolerance. Unlike diarrhea, constipation is a rare symptom that is noticed among people with lactose intolerance.

People consuming dairy foods and milk products can suffer from constipation as the lactose moves to the large intestine where the bacteria ferments the lactose and produces methane gas.

The production of methane gas slows the process of food moving to the gastrointestinal tract, causing constipation.

5.3. Headache and Migraine

Headache and migraine are also some of the early symptoms of lactose intolerance. Although, prescribed medications can be a temporary relief from migraines and headaches, following a healthy and balanced diet is essential.

5.4. Bloating and Stomach Cramps

Bloating and stomach cramps are also some of the early symptoms of lactose intolerance. When the lactose that has not been digested goes to the large intestine, the bacteria ferment the undigested enzyme lactase, producing acids and gases such as hydrogen, methane, and carbon dioxide.

The release of gases makes one feel bloated, whereas acids increase the amount of water in the large intestine causing pain in the stomach.

6. How Can You Diagnose Lactose Intolerance?

Based on the early symptoms of lactose intolerance and lifestyle, the doctor can suggest some tests with which lactose intolerance can be diagnosed. If the early symptoms of lactose intolerance worsen, the doctor may even suggest some tests.

Some of the tests that help to diagnose early symptoms of lactose intolerance are-

6.1. Hydrogen Breath Test

Boys Town Breath Hydrogen Test

A hydrogen breath test helps to identify the amount of hydrogen in a person’s breath. Usually, people with lactose intolerance have high levels of hydrogen in their breath.

In this test, you will be given a balloon-like bag to blow. After this, you will be given a lactose solution to drink. You will be then asked to blow a balloon-like bag every 20 minutes to two hours. If there is an increase in hydrogen in your breath, then it means that you are suffering from lactose intolerance.

This test can last up to 2-3 hours. You are advised not to smoke, eat or drink (even including water) for 12 hours before the test.

6.2. Glucose Test

The lactose tolerance test measures whether the glucose level in your blood rises or not. In this test, your doctor will take a blood sample before giving lactose solution to drink.

After drinking, your blood sample will be collected at certain intervals. This test continues for up to 2 hours. If your blood glucose level doesn’t rise, then it means that you are intolerant to lactose.

During this test, you will be advised not to smoke, eat or drink for 8 hours before the test.

Glucose Test for Lactose Tolerance — HHMI BioInteractive Video

6.3. Stool Acidity Test

The stool acidity test is mainly used for infants and children. In this test, a stool sample is collected to see if one is suffering from lactose intolerance or not.

This test is similar to other tests where they are given a lactose solution to drink. If they are intolerant to lactose, then the undigested enzyme will be fermented by bacteria present in the large intestine, producing lactic acid.

The presence of lactic acid means that the individual is lactose intolerant.

7. How can Lactose Intolerance be Treated?

Some of the early symptoms of lactose intolerance are temporary where it improves on its own if the underlying conditions are resolved. Otherwise, people also can manage their symptoms if they make some changes in their diet.

In most cases, changing diet or incorporating a healthy diet into their daily lifestyle can help people deal with their symptoms in a better way.

People with early symptoms of lactose intolerance are capable of taking a little bit of lactose in their diet whereas, people with severe intolerance to lactose have to either cut lactose from their diet, or choose better alternative options such as lactose-free milk, lactose-free foods, and lactose-free dairy products.

Also, lactase supplements can be taken before the meal. Those are available in capsule or powder form. Your intake of lactase supplements should depend on the amount prescribed by your physician.

These supplements have no side effects, although diabetic patients and pregnant women should avoid these unless prescribed.

7.1. Foods That Should be Avoided

People with early symptoms of lactose intolerance can have a tough time choosing the right lactose-free diet for them.

So, here is a list of the other foods that contain lactose that one needs to avoid-

• Dairy and Milk Products 

  • Fresh milk
  • Goat’s milk
  • Ice cream
  • Soft cheeses such as Feta, Roquefort, Cream cheese, or Ricotta
  • Yogurt
  • Condensed milk
  • Milk solids
  • Dry milk powder
  • Whey
  • Cheese

• Prepared Foods 

  • Coffee creamers
  • Breakfast cereals
  • Chocolates and candies
  • Baked items such as bread
  • Biscuits may also contain lactose
  • Butter

7.2. Foods You Can Have

Some of the alternating products that people with early symptoms of lactose intolerance can have are:

  • Milk substitutes such as almond milk, coconut milk, and soy milk. However, if you are allergic to milk, then try to avoid soy milk in your diet.
  • Green vegetables such as spinach, broccoli, and zucchini
  • Meat and fish such as tuna, chicken, beef, and salmon
  • You can even include eggs in your diet.
  • You can even have lactose-free yogurts.
  • You can have hard cheeses such as blue and parmesan cheese.


Now there you go, hopefully, the article was able to shed some light on lactose intolerance, its causes, and the early symptoms of lactose intolerance. Lactose intolerance is a permanent problem as you have to deal with it throughout your life and the symptoms can discomfort the affected.

However, there is nothing to worry about. There are enough lactose-free products available in the market. You just need to do proper research and consult your doctor before buying. You need to check the labels on the product to see if it is suitable for you or not.

  1. Matthews, Stephanie B., et al. “Systemic lactose intolerance: a new perspective on an old problem.” Postgraduate medical journal 81.953 (2005): 167-173. ↩︎
  2. Misselwitz, Benjamin, et al. “Lactose malabsorption and intolerance: pathogenesis, diagnosis and treatment.” United European gastroenterology journal 1.3 (2013): 151-159. ↩︎
  3. Swallow, Dallas M. “Genetics of lactase persistence and lactose intolerance.” Annual review of genetics 37.1 (2003): 197-219. ↩︎
  4. Lomer, Miranda CE, G. C. Parkes, and J. D. Sanderson. “lactose intolerance in clinical practice–myths and realities.” Alimentary pharmacology & therapeutics 27.2 (2008): 93-103. ↩︎
  5. Baumgart, Daniel C., and William J. Sandborn. “Crohn’s disease.” The Lancet 380.9853 (2012): 1590-1605. ↩︎
  6. Suri, Sheenam, et al. “Considerations for development of lactose-free food.” Journal of Nutrition & Intermediary Metabolism 15 (2019): 27-34. ↩︎

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Ananya Pal

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