Many different types of medications help treat Crohn’s disease, including a group of drugs known as biologics. Doctors often prescribe them for people with moderate to severe symptoms caused by Crohn’s disease.

Crohn’s disease is a chronic inflammatory bowel disease (IBD) that causes episodic inflammation, swelling, and irritation within the digestive tract.

There is no cure for Crohn’s disease but treatments, including medications, lifestyle changes, and surgery, can help manage symptoms.

Biologics are a group of medications engineered in a laboratory that are modified versions of natural proteins found within the body. These types of drugs work by interrupting the biological processes that lead to disease.

Compared with other types of medications for Crohn’s disease, such as corticosteroids, biologics can more specifically target the underlying causes of disease to help manage inflammation with fewer off-target side effects.

Biologics also include a group of medications known as biosimilars, which are structurally and functionally similar to other biologics that already have approval from the Food and Drug Administration (FDA) for the treatment of Crohn’s disease.

Biologics are available as injectable medications via intravenous (IV) or subcutaneous injection under the skin.

Biologics to treat Crohn’s disease consist of antibodies that block the activity of inflammatory molecules responsible for disease-causing processes.

There are three main categories of biologics currently used in the treatment of Crohn’s disease:

  • anti-tumor necrosis factor (anti-TNF) agents
  • integrin receptor blockers
  • interleukin inhibitors

Anti-TNF agents and interleukin inhibitors work by blocking certain proteins that promote inflammation within the intestine.

Integrin receptor blockers also prevent inflammation but work by blocking certain receptors on the surface of intestinal cells. This prevents immune cells that cause inflammation from entering the gut.

Different biologics work better for different people. Since there is no way to tell how a person will respond to each medication, doctors may try a few options until they find the right one to effectively induce and maintain remission.

Anti-TNF agents

Anti-TNF agents include:

  • adalimumab (Humira, Amjevita, Cyltezo, Hymiroz)
  • certolizumab (Cimzia)
  • golimumab (Simponi)
  • infliximab (Remicade, Renflexis, Inflectra, IXIFI)

Integrin receptor blockers

Integrin receptor blockers include:

  • natalizumab (Tysabri)
  • vedolizumab (Entyvio)

Interleukin inhibitors

Ustekinumab (Stelara) is a type of interleukin inhibitor for Crohn’s disease.

Doctors typically use biologics to treat Crohn’s disease that causes moderate to severe symptoms. They may be a stand-alone treatment or in combination with other types of medications or other biologics to provide better management if necessary.

As of 2021, the American Gastroenterological Association (AGA) recommends that biologic medications be used early in the course of Crohn’s disease treatment where suitable.

The AGA bases this recommendation on studies that found that people who started biologic medications early on had lower rates of relapse and fewer disease-related complications and were more likely to experience disease remission than those who began these medications later.

These recommendations represent a more proactive approach to the use of biologics, which doctors have typically reserved for people who have not responded to several other types of medications.

As of one decade ago, less than 1% of people with Crohn’s disease began a biologic as their first medication. With recent changes to treatment recommendations, the expectation is for this to change, which may help people reach remission quicker.

Biologics have become a mainstay of Crohn’s disease treatment because they allow for more targeted suppression of disease-causing immune processes. This may increase the effectiveness of treatment and reduce the likelihood of off-target effects in the body.

But the molecules involved in Crohn’s disease have other effects on the body, and some side effects can still occur.

Some possible side effects of Crohn’s disease biologic medications include:

  • injection-site reactions, such as itching, pain, or swelling
  • headaches
  • fever or chills
  • hives or other rashes
  • changes in liver function
  • immune-related effects, including arthritis and lupus-like reactions

Skin reactions and immune-related effects are most common with anti-TNF medications. On very rare occasions, these types of medications can also cause more serious side effects, including lymphoma or nervous system disorders.

Any changes in health or well-being experienced while taking a biologic should be discussed with a healthcare professional. Doctors who prescribe these medications may also recommend regular blood tests to help monitor for possible side effects.

Risk of infections

Biologics used to treat Crohn’s disease work by inhibiting parts of the immune system. While this helps manage inflammation caused by the disease, it can also affect the body’s ability to fight viral or bacterial infections.

People taking a biologic, including ustekinumab and adalimumab, for Crohn’s disease should have an evaluation for any underlying infections that may become active during treatment. This includes tuberculosis and hepatitis B virus infections.

A person should also be up to date with their vaccinations, including influenza, pneumococcal, and COVID-19 boosters, as recommended.

Any symptoms of infection — such as fever, cough, or chills — should be discussed with a healthcare professional as quickly as possible to help avoid serious illness.

Pros of biologics

  • specifically target the underlying causes of disease
  • subcutaneous administration is possible to do at home
  • starting biologics early on can lower rates of relapse and disease-related complications

Cons of biologics

  • side effects, including infections
  • IV administration requires attending a healthcare facility
  • safety concerns for people with other chronic conditions
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When deciding whether to start a biologic and which one to use, doctors may consider various factors in addition to safety and efficacy.

For instance, if a person has other medical conditions, it may affect the particular biologic a gastroenterologist chooses based on possible side effects or safety concerns.

According to a 2022 study from the United Kingdom, IBD specialists were more likely to choose vedolizumab over infliximab for people with Crohn’s disease who also had congestive heart failure, cancer, or chronic or recurring infections.

A doctor may also avoid anti-TNF agents for people with existing skin conditions. This is because studies have found they are the most commonly linked to skin side effects.

Since a person receives different medications by different routes — IV versus subcutaneous injection — doctors may also consider lifestyle factors when selecting treatment. Some IV medications may be less frequent, but they require people to visit a healthcare facility for several hours at a time for their infusion. A person can take some subcutaneous medications at home, or a healthcare professional can administer them quickly at an outpatient clinic.

Healthcare professionals will consider all of these factors and any other concerns a person may have when deciding on the right approach to treatment.

Biologic medications can be used at any point during the treatment of moderate to severe Crohn’s disease, with better results observed with earlier use. These medications can help people with unmanaged Crohn’s disease experience remission for long periods, either alone or in combination with other drugs.

An IBD specialist will consider several factors when choosing a biologic medication, including overall health and safety concerns. Serious side effects are uncommon but can happen with these medications, and any changes to a person’s health while taking these drugs should be discussed with a healthcare professional.