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What is an orphan drug?

Medically reviewed by Sally Chao, MD. Last updated on Sep 27, 2023.

Official answer


Orphan drugs are medicines developed to help treat, prevent or diagnose rare “orphan” diseases, which are conditions that each affect fewer than 200,000 people in the U.S. Today, about 600 orphan drugs are approved by the U.S. Food and Drug Administration (FDA) to treat these difficult and rare diseases.

Examples of orphan drugs include:

  • Ivacaftor: A therapy to treat cystic fibrosis, a genetic disorder that causes problems with breathing and digestion and affects about 30,000 Americans.
  • Alglucerase: A treatment for Gaucher disease, which causes pain and damage to tissue in the liver, spleen, lungs and bone marrow.
  • Coagulation factor IX: A drug that helps prevent bleeding in people with hemophilia B.
  • Imatinib: An oncology therapy to treat certain types of leukemia.
  • Rucaparib: A treatment for ovarian cancer.

Orphan drugs are expensive for patients, since they are created for small populations. The median annual cost for an orphan drug as of 2016 was over $32,000.

Orphan Drug Act

Developing a drug for a rare condition that treats a very small population can be costly. In order to spur pharmaceutical companies to develop more orphan drugs, Congress passed the Orphan Drug Act in 1983. This law encourages drug makers to research and manufacture orphan drugs by giving them tax incentives, subsidies for clinical research and the exclusive right to market these drugs for seven years.

The law has been a success, with the number of orphan drugs climbing steadily since 1983. The FDA approved nearly 600 orphan drugs between 1983 and July 2020, according to the National Organization for Rare Disorders (NORD). That compares with only 38 orphan drugs before the Orphan Drug Act became law.

According to a 2021 study by NORD, 599 orphan products were approved to treat rare diseases by the FDA between 1983 and July 2020, with about 552 still on the market today.

Rare diseases include such well-known conditions as cystic fibrosis, Lou Gehrig's disease and Tourette's syndrome. But they also include such unfamiliar diseases as acromegaly, or “gigantism,” and the curiously named Jumping Frenchman of Maine, an extremely rare disorder that causes an extreme startle reaction to unexpected noises or sights. New rare diseases are discovered each year. Most are genetic in origin, though others can result from environmental and toxic conditions.

Even though each disease affects relatively few people, more than 30 million people in the country experience one of some 7,000 rare diseases.

Many rare diseases are life-threatening, and children account for over half of those afflicted. FDA-approved treatments are available for less than 10% of all rare diseases.

  1. National Cancer Institute (NCI). Orphan Drug. Available at: [Accessed September 2, 2021].
  2. QuintilesIMS Institute. Orphan Drugs in the United States. October 2017. Available at: [Accessed September 2, 2021].
  3. National Organization for Rare Disorders (NORD). New Study Investigates the Number of Available Orphan Products, Generics and Biosimilars. March 25, 2021. Available at: [Accessed September 2, 2021].
  4. U.S. Food and Drug Administration (FDA). Rare Diseases at FDA. Available at: [Accessed September 2, 2021].
  5. U.S. Food and Drug Administration (FDA). Orphan Products: Hope for People With Rare Diseases. March 1, 2018. Available at: [Accessed September 2, 2021].

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