What Are the Symptoms of Lactose Intolerance?

woman using a laptop

Even though intolerance to lactose is not life-threatening, it can make those that suffer from it uncomfortable and miserable. When someone that is lactose intolerant eats dairy products, they can suffer from a range of symptoms. Because of a deficiency in lactase, some people cannot digest lactose, which is sugar found in dairy products. When this happens, your body won’t be able to break the lactose down into glucose so you can absorb it into your bloodstream for energy.

The best advice is to avoid drinks and food that have lactose in it or by taking a lactase digestive supplement. Here are a few indications that are commonly seen in someone that is lactose intolerant that can help you determine if you are as well.

1. Stomach Pain

stomach pain

Stomach pain is the number one symptom of being lactose intolerant. Typically when you have stomach pains or aches, you attribute it to something you ate. If you are lactose intolerant, you are experiencing the pain because you can’t break down lactose. The cells that line the colon will not absorb lactose, so it will sit there fermenting until it is broken down by the bacteria that naturally live there. During the fermentation process, carbon dioxide, methane, and hydrogen are released, causing stomach cramps and pain.

2. Bloating and Gas

bloated stomach

Bloating is another common symptom that is uncomfortable to experience. Bloating can cause you to be embarrassed when you are sitting or make your clothes feel tight. If you are lactose intolerant, bloating will occur with an increase in gas and water in your colon. This can cause your stomach to gurgle or your stomach to distend as the walls of your gut stretch out. Depending on how much lactose you have consumed, and how sensitive you are, your bloating and distended stomach can vary. At the same time, you will also suffer from gas. Not only is gas embarrassing, but it can be very uncomfortable when you try to suppress it. Everyone experiences different amounts of gas depending on how well their colon reabsorbs gas.

3. Diarrhea and Constipation

tissue on the wall

Although it’s it indeed not dinner conversation material, diarrhea is a part of life, especially if you are lactose intolerant. It occurs when you have too much water in your colon, making your stool watery. And, when you have lactose and acids that are leftover, you have more water than usual released into your colon, causing your body to have diarrhea. Even though most those most people who are lactose intolerant suffer from diarrhea, some sufferers report constipation as a symptom. When your colon is fermenting undigested lactose, it also produces methane gas which can slow down your digestive process. This can prevent food from passing through your gut on time and ultimately result in constipation.

4. Nausea and Vomiting

man with nausea

Since we already know that bloating can cause you to feel nauseous and even to vomit, it is the next symptom on our list. If you are lactose intolerant, you may feel sick for 30 minutes to two hours after you ingest a milk product.

5. Age

mother playing with baby

There are a couple of kinds of intolerance to lactose. Sometimes it will occur when you are born, and sometimes it develops when you are an adult, and other times it develops after you have damaged your small intestine. Although it is infrequent to be born without lactase as at all, it can happen. Most people develop their intolerance to lactose after they are two. Plus, this rare disorder affects almost 30 million people in the United States by the time they are 20. Here are the different types of lactose intolerance.


The results of healthy aging, a primary intolerance is the most common type. As you age, the amount of lactase you make can decrease since you rely less on milk as an adult. This is a gradual process, so it may not appear until you are older.


In this case, a secondary intolerance can be a result of an injury or illness. If you have inflammatory bowel disease and celiac disease or have had surgery on your small intestines, you can find yourself becoming lactose intolerant. In this case, lactase levels can be restored with treatment.


Although very rare, intolerance to lactose can be inherited. When a defective gene is passed to a child from his parents, there can be a total absence of lactase in the baby. Babies born with this condition are intolerant of breast milk. Since this can cause dehydration and loss of electrolytes from diarrhea, it can be life-threatening. Fortunately, this is a manageable condition to treat by feeding the baby lactose-free infant formula in place of milk.


Premature babies can develop this intolerance to lactose due to the face that a baby does not start lactase production until later in pregnancy, usually not before 34 weeks.

6. Ethnicity

hands from all ethnicity

Also, if you happen to be a specific ethnic, you will have a higher chance of developing it than other ethnic groups. Even though everyone was fed milk as a baby, adults have only started digesting lactose about  5,000 years ago. Through genetics, East African and Caucasian populations have allowed for the presence of lactase in their bodies. Other African communities, as well as South and East Asian people, have seen more adults that have experienced signs of intolerance to lactose.

7. Other Signs

man with holding his knees

Usually, signs are gastrointestinal based, but other symptoms have also been reported as well, including:

• Eczema
• Urinating problems
• Mouth ulcers
• Joint and muscle pain
• Problems concentrating
• Fatigue
• Headaches

Keep in mind that while these signs can be real signs of being lactose intolerant, separately, they can be attributed to other causes.

Lactose Intolerance vs. Milk Allergies Symptoms

Being allergic to milk and being lactose intolerant are often confused as the same thing. Although they are two very different conditions, they usually have the same signs. However, milk allergies are based in the immune system, while intolerance to lactose is found in the digestive system.

cheese and brown bread

Signs of milk allergies include vomiting, wheezing, and hives right after the sufferer have consumed a milk product. Other symptoms can include an itchy rash, watery eyes, runny nose, coughing, cramps, and diarrhea. Since it is due to your body’s inability to break down lactose, its signs are more related to gas, diarrhea, nausea, and bloating than anything life-threatening. Plus, a milk allergy is something that you can outgrow while being lactose intolerant is something you can have into adulthood.

If you find yourself suffering from signs of lactose intolerance, you can help to diagnose the condition by using a hydrogen breath test which will tell you if you have lactose malabsorption or that your signs are due to some other issue. To treat it, you will have to remove or radically reduce lactose from your diet. How severe the condition is dependent on the person, so it is vital to find out what the right amount of dairy in your diet is, so you can stop the uncomfortable signs from occurring.

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