Crohn’s disease and lactose intolerance can both cause similar digestive symptoms, such as diarrhea and abdominal pain. However, the causes and treatment of these two conditions are very different.

A person who may experience lactose intolerance or Crohn's pours soy milk into cerealShare on Pinterest
AsiaVision/Getty Images

In this article, we look at Crohn’s disease and lactose intolerance in more detail and compare their causes, symptoms, risk factors, diagnosis, and treatment.

Crohn’s disease is a long-term condition that causes inflammation of the digestive tract. Crohn’s disease is a type of inflammatory bowel disease (IBD). According to estimates, doctors diagnosed IBD in more than 3 million adults in the United States in 2015.

Lactose intolerance affects around 30 to 50 million U.S. adults. People with this condition are unable to digest a type of sugar called lactose, which is present in milk and most other dairy products.

For individuals with lactose intolerance, consuming products containing this sugar can cause similar symptoms to Crohn’s disease. However, the two conditions have very different causes and treatments.

Crohn’s disease

The exact cause of Crohn’s disease is not clear, but doctors think that it may have autoimmune characteristics, meaning that the immune system mistakenly attacks healthy tissues in the body. Experts also think that a person’s genes and other factors, such as smoking or previous infection, may play a role in the development of this condition.

Crohn’s disease can occur anywhere along the digestive tract, but it most commonly affects the small intestine or the start of the colon. The inflammation can affect several areas of the digestive tract at once, and the symptoms can vary considerably.

Lactose intolerance

People with lactose intolerance are unable to break down lactose because they do not produce enough of an enzyme called lactase. The body uses lactase to break lactose down into two simpler sugars called glucose and galactose.

Undigested lactose moves into the colon, where bacteria ferment it. This process leads to a buildup of gases and fluids that cause the symptoms of lactose intolerance.

Lactose intolerance affects people differently. Many people with this intolerance can consume small amounts of lactose without experiencing symptoms, but others cannot.

There are three main types of lactose intolerance:

  • Primary lactase deficiency results from a gene that runs in some populations. Symptoms of this type of lactose intolerance typically manifest after weaning.
  • Secondary lactase deficiency develops when a disease, infection, or another condition injures the small intestine. This type of lactose intolerance is sometimes only temporary.
  • Congenital lactase deficiency is rare but usually starts from birth.

Both Crohn’s disease and lactose intolerance affect the digestive system. For this reason, there is an overlap in their symptoms. Both conditions cause the following symptoms:

  • diarrhea
  • abdominal pain or cramping
  • nausea

However, each condition also has its own specific symptoms.

Crohn’s disease

Symptoms that are specific to Crohn’s disease include:

  • reduced appetite
  • unintentional weight loss
  • anemia
  • eye and skin irritation and redness
  • fatigue
  • fever
  • pain or soreness in the joints
  • less commonly, bloody stool

The symptoms of Crohn’s disease can vary depending on the location of the inflammation inside the digestive tract and its severity.

Lactose intolerance

Symptoms that are specific to lactose intolerance include:

  • gas
  • bloating
  • vomiting
  • stomach growling

The risk factors for Crohn’s disease and lactose tolerance are also different:

Crohn’s disease

Many environmental factors may increase the risk of Crohn’s disease, including:

  • smoking
  • taking oral contraceptives
  • digestive tract infections
  • antibiotic use
  • removal of the appendix

There may also be certain genetic factors that increase the likelihood of Crohn’s disease, which means that the condition may run in families.

Lactose intolerance

The following factors may increase the risk of lactose intolerance:

  • premature birth
  • infections, diseases, or conditions that injure the small intestine, which can include IBD and celiac disease
  • genetic factors

There is a higher prevalence of lactose intolerance in areas of the world where people rarely consume milk and other dairy products. For example, more than 90 percent of people of East Asian descent are intolerant to lactose.

The diagnosis of both Crohn’s disease and lactose intolerance generally involves a physical examination and the assessment of a person’s medical history.

A doctor may also carry out additional tests to diagnose each of these conditions.

Crohn’s disease

To diagnose Crohn’s disease, a doctor can use many different tests and scans, which include:

  • Blood tests to check for signs of inflammation
  • Stool tests to rule out other conditions
  • Endoscopy or colonoscopy, in which a doctor will insert a thin tube with a light and camera down a person’s throat or up through their rectum to check for inflammation inside the digestive tract
  • X-rays or CT scans, which allow a doctor to see inside the body to check for signs of the condition

The doctor may use a combination of these tests to confirm a diagnosis.

Lactose intolerance

To determine whether or not someone has lactose intolerance, a doctor may ask them to avoid all foods and drinks containing lactose for a few weeks. If the symptoms disappear, lactose intolerance is likely to be the cause.

In some cases, the doctor may ask a person to undergo a hydrogen breath test. The test involves drinking a liquid that contains a small amount of lactose and then breathing into a plastic bag every 15 or 30 minutes for 2–3 hours.

People with lactose intolerance have higher levels of hydrogen in their breath after consuming lactose. If the hydrogen levels in the person’s breath rise during the test and their symptoms worsen, it is likely that they are intolerant to lactose.

Both Crohn’s disease and lactose intolerance are long-term conditions with no cure, so the aim of treatment is to manage the symptoms.

Crohn’s disease

Treatment for Crohn’s disease will depend on the type and severity of a person’s symptoms, but it may include:

  • Aminosalicylates. Doctors typically prescribe these for mild symptoms, and they work by reducing inflammation.
  • Corticosteroids. These medications are suitable for people with moderate-to-severe symptoms. They suppress the immune system and reduce inflammation.
  • Immunomodulators. Doctors tend to prescribe these when other treatments fail to relieve a person’s symptoms. Immunomodulators suppress the immune system, but they can take several weeks to have an effect.
  • Biologic therapies. These medications use biological substances, such as antibodies, to target and deactivate immune system proteins, which helps reduce inflammation. These therapies are another option that doctors turn to when a person’s symptoms do not respond to other treatments.

A doctor may also prescribe or recommend other medications to treat specific symptoms, such as:

  • acetaminophen for mild pain
  • antibiotics for treating digestive tract infections
  • loperamide for relieving diarrhea

It may also be possible for people to reduce or prevent their symptoms by making certain lifestyle changes, such as:

  • quitting smoking and the use of other tobacco products
  • avoiding high-fiber foods
  • avoiding cola, soda, and other carbonated drinks
  • keeping a food diary to identify foods that trigger or worsen symptoms
  • adopting a specific diet that a doctor or dietician recommends

For more severe cases of Crohn’s disease, a doctor may recommend surgery. Surgery can treat complications that pose a significant health risk, such as internal bleeding or intestinal blockages.

Lactose intolerance

The treatment for lactose intolerance typically involves restricting lactose consumption or eliminating it from the diet entirely, depending on how much lactose a person can tolerate.

A low-lactose or lactose-free diet can be challenging as dairy products are widespread in most Western diets. People should also take care to compensate for any dietary changes to ensure that they are not lacking any nutrients, such as vitamin D and calcium.

A doctor or dietitian can advise on a diet plan to suit a person’s specific needs. For some people, a doctor may recommend using lactase products, which are tablets or drops that contain lactase to help the body digest lactose.

Crohn’s disease and lactose intolerance both affect the digestive system and can cause similar symptoms. However, the causes, risk factors, diagnosis, and treatment of the two conditions are different.

Crohn’s disease occurs due to a problem with the immune system, and symptoms result from inflammation in the digestive tract. People with lactose intolerance do not produce enough lactase and experience symptoms when they consume products containing lactose.

Both can be lifelong conditions, but lactose intolerance is generally easier to manage than Crohn’s disease.

Doctors usually treat a person with Crohn’s disease using medications that reduce inflammation and suppress the immune system. Surgery may sometimes be necessary to treat serious complications.

People with lactose intolerance can prevent symptoms by adopting a low-lactose or lactose-free diet.

Read the article in Spanish.