A couple from New York is suing the makers of Taxotere, a treatment for breast cancer that they say causes permanent baldness.

Plaintiffs Julieann and John R. are taking on Sanofi SA and its related businesses, all of whom are responsible for the development, manufacture or marketing of Taxotere.

Taxotere is a chemotherapy drug that sees particularly frequent use as a treatment for breast cancer.

The plaintiffs say Julieann underwent chemotherapy with Taxotere from August 2012 through March 2013. Following that treatment, Julieann suffered from disfiguring permanent alopecia, according to her Taxotere lawsuit.

Julieann now claims that her permanent hair loss was caused by the Taxotere used in her treatment for breast cancer. She says that neither she nor her treatment providers were aware that using Taxotere can leave the patient permanently bald.

Hair loss is a common side effect of treatment for breast cancer. However, hair lost during chemotherapy typically grows back.

Julieann claims Taxotere is unusual among chemotherapy drugs in that it creates a much greater likelihood that any hair loss suffered will be permanent.

Had she known about that likelihood, Julieann claims, she never would have taken Taxotere.

Plaintiffs: Sanofi Concealed Risks of Treatment for Breast Cancer

Julieann and John accuse Sanofi of purposely covering up the link between Taxotere and permanent hair loss.

They claim that Sanofi used publications and marketing materials to deceive the public and the medical community into believing that hair lost because of Taxotere would eventually grow back.

The plaintiffs argue that Sanofi knew about Taxotere’s ability to cause permanent baldness because of the results of some of Sanofi’s own clinical studies.

By 2005, they say, results from the Sanofi-sponsored GEICAM 9805 study showed that over 9 percent of patients studied continued to have hair loss for at least 10 years, and sometimes longer, after discontinuation of chemotherapy.

Another study by a Denver-based oncologist reported that more than 6 percent of his patients suffered persistent hair loss that lasted years after they had stopped taking Taxotere.

Regulatory agencies in Canada and the European Union have also required Sanofi to add warnings to its promotional materials for Taxotere that address the drug’s increased risk of permanent hair loss.

But in the U.S., Sanofi tells patients that “hair generally grows back,” according to Julieann and John’s Taxotere lawsuit.

Plaintiffs say that the words “permanent alopecia” or “permanent hair loss” did not appear on any Taxotere labeling or promotional materials in the U.S. until December 2015 at the earliest.

The plaintiffs argue that without a proper warning, patients facing chemotherapy do not get an opportunity to make an informed decision on whether the possible benefits of Taxotere are worth the drug’s risks.

They claim Sanofi enjoyed revenues in the billions of dollars while exposing patients to a risk they weren’t made aware of.

John, Julieann’s husband, is bringing his own claim for loss of consortium. Loss of consortium seeks to compensate the spouse of a person who has been harmed, based on the effect that harm has on their marital relationship.

The Taxotere Lawsuit is Case No. 2:16-cv-17720 in the U.S. District Court for the Eastern District of Louisiana.