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What are biologic drugs and how do they work?

Medically reviewed by Sally Chao, MD. Last updated on Jan 20, 2025.

Official Answer by Drugs.com

What is a biologic?

A biologic is a drug or vaccine made from a living organism. A biologic can be made from proteins, sugars, DNA, cells or living tissue, for example. The source may be human, animal or a microorganism (like a bacteria or virus).

You might require a biologic product, like gene or protein therapy, to treat diseases such as cancer or arthritis, especially if conventional drugs prove ineffective or if biologics offer better results. Hormones like insulin are also considered biologics. Additionally, biologics can be used as vaccines to prevent diseases, like the vaccine for human papillomavirus (HPV) that helps prevent cervical cancer.

Generally, when people mention “biologics,” they're referring to specialized drug treatments.

What's the difference between a biologic and a conventional drug?

Biologics are different from conventional chemical drugs in several ways.

Biologics activate certain proteins or cells in your immune system to create specific responses to targets, while many conventional systemic drugs activate your entire immune system in a more generalized manner.

Because biologic drugs are so complex:

Also, because biologic drugs are made from living organisms, they may be more at risk for contamination, so they usually need to be refrigerated.

All biologic drugs and biosimilars must be approved by the Food and Drug Administration (FDA) for safety and effectiveness, just like conventional drugs.

How do different types of biologics work?

Biologics are relatively new drugs that can greatly improve the lives of people with many conditions and diseases. Many biologics are now available, and more are being studied in research trials.

For some people, a biologic may be the only drug that works. Biologics may offer the best treatments for a variety of medical diseases and conditions that have been difficult to treat in the past.

There are several types of biologics that work in different ways:

There are dozens of biologics approved to treat many diseases. According to the Congressional Research Service, the top 10 best-selling biologics are:

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What are the side effects of biologics?

Different biologics have different side effects, but some side effects are common to most biologics. These include an increased risk of infection and both body and skin reactions after receiving the biologic.

Biologic medications that work by suppressing the immune system can cause a higher risk for colds and other upper respiratory tract infections, as well as worsen an existing, long-term infection, so you may be checked for a long-term infection like tuberculosis, hepatitis or other infectious diseases before you start treatment.

Some biologics have been associated with an increased risk for some types of cancer. In the past, studies have found a slightly increased risk for lymphoma and skin cancer. Because a biologic may affect your immune system, you may be advised not to have certain vaccinations that use a live virus. To date, biologics have not been studied widely during pregnancy or breastfeeding to confirm that they are safe. In cases where there may be a risk from a biologic, that risk must be weighed against the benefits of treatment.

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References
  1. U.S. Food and Drug Administration (FDA). What Are “Biologics” Questions and Answers. February 6, 2018. Available at: https://www.fda.gov/about-fda/center-biologics-evaluation-and-research-cber/what-are-biologics-questions-and-answers. [Accessed January 5, 2022].
  2. American Diabetes Association (ADA). Insulin is Now a Biologic—What Does That Mean? March 23, 2020. Available at: https://www.diabetes.org/blog/insulin-now-biologic-what-does-mean. [Accessed January 11, 2022].
  3. U.S. Food and Drug Administration (FDA). Gardasil Vaccine Safety. August 20, 2009. Available at: https://www.fda.gov/vaccines-blood-biologics/safety-availability-biologics/gardasil-vaccine-safety. [Accessed January 9, 2022].
  4. Arthritis Foundation. Biologics. Available at: https://www.arthritis.org/drug-guide/biologics/biologics. [Accessed January 5, 2022].
  5. National Psoriasis Foundation. Biologics. Available at: https://www.psoriasis.org/biologics/. [Accessed January 5, 2022].
  6. Congressional Research Service. Biologics and Biosimilars: Background and Key Issues. June 6, 2019. Available at: https://sgp.fas.org/crs/misc/R44620.pdf. [Accessed January 5, 2022].

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