Tampons and Endometriosis

Can endometriosis result from menstrual blood flowing backward through the fallopian tubes into the pelvic cavity? If so, could the use of tampons increase the likelihood of this backward flow and potentially worsen endometriosis?

Background

One of the most accepted theories of the pathogenesis (mechanism) of endometriosis is the one presented in 1940 by the American gynecologist John Sampson (1873 – 1946). This research paper, which later became known as the Retrograde Menstruation theory, suggests that endometriosis develops as a result of menstrual blood flowing backward through the fallopian tubes and into the pelvic cavity.

Although this theory is widely accepted, it does not explain all cases of Endometriosis. In addition, because his work has often been poorly presented, many scientists are unaware that Dr. Sampson wrote 18 scientific papers on the subject. In a paper published in 1927, Sampson also described another possible mechanism in which endometrial cells could spread through blood vessels or the lymphatic system. This idea later became known as the embolic spread theory. According to this theory, the development of endometriosis in unusual locations, such as the umbilicus and other extra-genital areas, as well as deep invasive recto-vaginal septum endometriosis, pre-menarchal and very severe adolescent endometriosis, may be explained by the transport of endometrial cells through these circulatory pathways.

Introduction

If retrograde menstrual flow can contribute to the development of endometriosis, then anything that interferes with menstrual blood freely leaving the body could potentially increase the likelihood of this backward flow. For example, if menstrual blood is prevented from exiting normally, it may increase the chance that some of the blood will move upward through the fallopian tubes into the pelvic cavity.

Endometrial cells carried upward by retrograde menstrual flow can implant and grow on the peritoneum, the membrane lining the abdominal cavity and covering organs such as the stomach, spleen, and intestines. These cells may grow on the surface of this lining or invade deeper into abdominal or pelvic organs. Once implanted, the lesions behave similarly to the normal uterine lining and respond to hormonal changes during the menstrual cycle. However, because this tissue is located outside the uterus, the menstrual material cannot easily exit the body, which can lead to inflammation and severe pain.

Tampons and Retrograde Menstrual Flow

If one asks an AI platform whether there is a correlation between Endometriosis and tampon use, the answer may appear to be a simple “no.” However, the issue may be more complex than that. Research on tampon use and endometriosis can be difficult to trace in mainstream citation databases. One reason is that some studies were not widely indexed in major medical databases such as PubMed or Web of Science. Another reason is that some research was published internationally and circulated mainly in local reports rather than widely distributed journals. For example, a study published in 1997 by the University of the Free State in South Africa reported a correlation between tampon use during menstruation and endometriosis.

While most studies found in PubMed and other medical databases report no correlation between tampon use and Endometriosis, many explicitly or implicitly note that further research is needed. For example, a 1985 study titled “Tampon Use in Women with Endometriosis” surveyed 470 members of the Endometriosis Association and found that 82 percent of respondents routinely used tampons. However, the study concluded that this rate was similar to that of the general population (75–83 percent). The authors also emphasized the lack of existing data on menstrual practices, suggesting that their work should be viewed as an early exploratory investigation and highlighting the need for additional research.

A 2024 review published in Archives of Gynecology and Obstetrics examined whether menstrual products, such as tampons and menstrual cups, might play a mechanical role in the development of endometriosis. The review concluded that the evidence is inconclusive, but it noted a study by Darrow and colleagues, which found that using tampons for 14 years or more was associated with a higher risk of endometriosis.

“... using tampons for 14 years or more was associated with a higher risk of endometriosis.”

Other Issues with Tampons

In addition to the possibility that tampons may mechanically contribute to retrograde menstruation, there is another potential risk associated with their use during menstruation: Toxic Shock Syndrome. This condition occurs when certain bacteria grow and produce toxins that can enter the bloodstream and trigger a severe immune response.

Tampon use—particularly with high-absorbency products—may increase this risk, as these tampons can remain in place longer and create an environment where bacteria can multiply. In addition, tampons can sometimes cause small tears (micro-abrasions) in the vaginal lining, which may make it easier for toxins to enter the bloodstream.

Dioxin exposure was a major environmental and public health concern in the 1990s and was often described as one of the most dangerous man-made chemicals. In November 1996, Congresswoman Carolyn B. Maloney introduced the Tampon Safety and Research Act of 1997 to support research on whether dioxins, synthetic fibers, and other additives in tampons pose health risks. Today, tampons are manufactured using tightly controlled bleaching processes that result in only trace or negligible levels of dioxins. However, public concern persists because dioxins are classified as persistent organic pollutants, meaning they can accumulate in the food chain and in body fat over time. According to the World Health Organization, dioxins remain in the body for long periods due to their chemical stability and their tendency to be stored in fat tissue. Their half-life in the human body is estimated to be 7 to 11 years.

“Their [dioxin] half-life in the human body is estimated to be 7 to 11 years.”

Sex During Menstruation

There are no clinical guidelines that recommend avoiding sexual activity during menstruation. However, some research suggests a possible increase in endometriosis among individuals who engage in sexual activity during this time. One proposed explanation is that sexual activity during menstruation may increase retrograde menstruation. One study found that surgically diagnosed endometriosis was significantly more common among individuals who engaged in sexual activity during menstruation. In a 2022 case-control study of 555 women—185 with endometriosis and 370 without—researchers also found an increased risk of endometriosis among those who reported menstrual intercourse compared to those who did not.

TCM and Endometriosis

An article published by the Endometriosis Foundation of America where several studies were cited, concluded that acupuncture can reduce pain, improve immune function, decrease cellular estrogen levels, and decrease inflammation as measured by the biomarker CA-125. It is worth mentioning that while the blood biomarker CA-125 can be elevated in endometriosis, it cannot be used on its own to diagnose or rule out the condition. The gold standard procedure to properly diagnose endometriosis is laparoscopy.

Conclusion

Overall, existing research supports a strong association between retrograde menstrual flow and the development of endometriotic lesions. However, the potential influence of menstrual product use—particularly tampons—on increasing retrograde menstrual flow remains insufficiently explored. While some evidence suggests that tampon use and sexual activity during menstruation may be associated with a higher risk of endometriosis, the underlying mechanisms are not yet clearly understood. Given the widespread use of tampons, this represents an important gap in the literature.