Undergraduate Writing Series
The Sixteen Year Gap: Women in Medical Trials and the Side Effects Today

The Sixteen Year Gap: Women in Medical Trials and the Side Effects Today

Beatrice Titus

Historically, women have been excluded from clinical trials creating a gender gap in pharmacology. This means that medication is geared towards men, benefiting men’s health more than women’s. After the thalidomide crisis, US laws excluded many women from drug trials for medications that were ostensibly for all adults until 1993. Despite legal changes, the issue continues today as there are still few studies done on how the female body reacts to medication. Women today continue to experience more side effects from medications than men due to the lack of female representation in clinical trials.

In the 1950s, the drug thalidomide made its way to the marketplace and in people’s medicine cabinets. A German company named Chemie Grünenthal GmbH initially created the drug as a tranquilizer, but it was also used to treat pregnant women’s morning sickness. The drug was produced under 37 names in 46 different countries, making it difficult for medical professionals to make the connection that thalidomide had an impact on fetal development. It took five years before doctors began to recognize that the drug had a variety of effects on limbs, organs, eyesight, and hearing. Before the drug was officially taken off shelves, it affected over 10,000 babies around the world–with nearly half ending in mortalities. Despite the drug recall, its wide variety of names caused confusion. In 1962, President John F. Kennedy formally addressed the United States about thalidomide, advising all women to check their medicine cabinet because of the fear that people may be harboring the drug without knowing its hazards.[1]

A pack of Thalomide pills, with box and aluminum pill pack.
Pack of Thalidomide tablets circa 2006 or later. (Courtesy Wikimedia)

The thalidomide crisis led to reform in drug development and distribution. Following the crisis, the United States recommended a 25% increase in staff in the Food and Drug Administration (FDA).[2] In 1977, the FDA issued a document titled “General Considerations for the Clinical Evaluation of Drugs,” which proclaimed that only women without childbearing capabilities could participate in clinical trials. Women could not participate in the early stages of drug trials including phase 1 and phase 2 clinical trials.[3] A clinical trial in phase 1 is designed to test the drug’s safety among humans and progresses to phase 2, which then determines the right dosage of the drug that can effectively treat a particular disease. This policy was designed to avoid another tragedy like the thalidomide crisis, but created even greater long-term challenges for women and medication.

In 1993, the FDA reversed its decision in its “Guideline for the Study and Evaluation of Gender Differences.” The reversal lifted the regulations placed on women of child-bearing potential and left the decision of early clinical trial participation up to researchers and potential women participants.[4] Soon after, the FDA issued a new policy, “Presentation of Safety and Effectiveness Data…” in 1998. It outlines guidelines for New Drug Applications (NDA) and states that demographic groups, gender, age, and race must be reported for safety. Despite the efforts of the 1993 and 1998 decisions, thousands of drugs approved before 1993 still exist in the marketplace today. This means that there is a significant number of drugs on the market that were not mandated to consider sex differences.

Sixteen years of excluding women of child-bearing potential from participating in clinical trials have caused repercussions that still linger today. In a study completed by the University of Chicago and University of California Berkeley in 2020, researchers discovered that women are overmedicated and suffer excessive side effects. This occurs because drug dosages are computed based on male subjects. The study also concluded that women have been left out of clinical trials because female hormones make it difficult to study women. Brian Prendergast, an author of the study, noted that “For much of the time it’s been practiced, biomedical science has been done by men, on men,” starting even in the early stages of animal testing. Women and men react differently to pharmaceuticals due to numerous parameters such as weight, muscle mass, enzymes, and plasma proteins, yet are still given the same dosages. The study evaluated 86 drugs and their adverse reactions. In 96% of cases, women experienced higher adverse drug reactions while men experienced only 29% of adverse drug reactions. The COVID-19 vaccine is a direct example of women experiencing more side effects than men. Around the world, women have reported worse side effects than men after the vaccination: 68.7% in Switzerland, 61.2% in the United States, and 83% in Norway. While women are required to participate in trials in the present day, there is still a clear difference in how the drugs affect the different sexes, which is a consequence of the 1977 policy.

In 2021, the distribution of the Johnson & Johnson vaccine in the United States was halted due to concern that it may affect fertility. This was disproven in April 2021, and the Center for Disease Control and Prevention resumed its use. However, the side effects listed for the vaccine concern women under the age of 50. The emphasis on women under the age of 50 is significant due to the previous regulations placed on child-bearing potential in women. The average woman’s reproductive potential lasts between the ages of 12 and 51. This means that to this day, there is still a gap in knowledge on hormonal processes in female bodies, ultimately leading to a lack of advancement in medication for women.

Recent studies have emphasized that the medical community needs to spread awareness that women are put at a disadvantage when taking prescription drugs because of policies excluding them from early clinical trials. Medicine is not one size fits all, and it is time that the medical community recognizes the disadvantages that women face. Moreover, women are not the only group that face lack of representation. There is a need for more research on all kinds of bodies, including trans women, trans men, and people born with intersex traits. All bodies are not the same, nor should they be treated the same.


  1. Federal Register Division. National Archives and Records Service, Public Papers of the Presidents of the United States, John F. Kennedy, 1962 (Washington, DC: Government Printing Office), 590–98.
  2. Federal Register Division. National Archives and Records Service, Public Papers of the Presidents of the United States, John F. Kennedy, 1962 (Washington, DC: Government Printing Office), 590–98.
  3. Katherine A. Liu and Natalie A. Dipietro Mager, “Women’s Involvement in Clinical Trials: Historical Perspective and Future Implications.” Pharmacy Practice 14, no. 1 (2016): 708. https://doi.org/10.18549%2FPharmPract.2016.01.708
  4. Liu and Dipietro Mager, “Women’s Involvement in Clinical Trials,” 708.

Featured image caption: (Courtesy Polina Tankilevitch on Pexels)

Beatrice is an undergraduate at Mercyhurst University studying Intelligence Studies. She is simultaneously pursuing a graduate degree in Applied Intelligence.