Twirla, a new low-dose contraceptive patch, is effective at preventing pregnancy among American women, according to researchers.

Phase III clinical trial results were favorable for efficacy, safety, and tolerability of a levonorgestrel/ethinyl estradiol transdermal delivery system. The new patch uses a progestin and contains less estrogen than prior patches. It is believed to be associated with a lower risk of blood clot formation.1

“Women used one patch a week for three weeks, then wore no patches for one week to have scheduled bleeding,” says Anita L. Nelson, MD, study author and professor and chair of obstetrics and gynecology at Western University of Health Sciences in Pomona, CA. “The trial design explicitly sought to test this new product in women who were more representative of real potential users in the U.S. For example, there was no limit placed on weight. As a result, 35.3% of subjects had a body mass index [BMI] over 30 kg/m2 — [classified as] obese.”

Also, women were enrolled from a diverse sample of races and ethnicities. “The overall pregnancy rate for all participants was 5.8%,” she says. “But, it is clear that the patch works better for non-obese women.”

For women with a BMI of 30, the pregnancy rate at one year was 4.3%. For women with lower BMI, the failure rate was 3.5%.1

“Bleeding patterns were well tolerated by users,” Nelson adds. “There were four women who experienced blood clots, and all of them had BMIs equal to or greater than 30.”

One in 10 women reported some degree of itching or skin irritation. Overall, the patch adhered reasonably well, Nelson says.

“Eleven percent of women discontinued due to treatment-related complications,” she adds. “Because of the lower efficacy and the observed blood clots seen in women with BMI greater than or equal to 30, the product carries the same FDA labeling as the other available patch, Xulane. Each is indicated only for women with BMI less than 30.”

Twirla is like a 30 mcg contraceptive pill, while Xulane is closer to a 50 mcg pill, she notes.

“The levonorgestrel in Twirla has been associated with the lowest blood clot risk in oral contraceptives, whereas the Xulane patch progestin is like other formulations with higher rates,” she adds. “We did not compare the other methods, but only one in 10 women discontinued using the patch during the one-year study because of adverse events they thought came from the patch.”

From a reproductive health provider’s perspective, the new, once-a-week patch is an attractive option to women with BMIs below 30 kg/m2, particularly if they have difficulty taking a daily pill and do not want to use vaginal devices.

“It would also be a good option for women who are not able to absorb hormones from pills due to stomach or intestinal problems,” Nelson says. “The visibility can be very reassuring — she has it on her, and she doesn’t need to wait until she gets home to see if she took today’s pill.”

Patches are highly portable, making them convenient for travel. “This patch offers non-obese women a non-daily transdermal contraceptive option they control, and that reduces estrogen exposure with favorable effectiveness, safety, and tolerability,” she adds.


  1. Nelson AL, Kaunitz AM, Kroll R, et al. Efficacy, safety, and tolerability of a levonorgestrel/ethinyl estradiol transdermal delivery system: Phase 3 clinical trial results. Contraception 2020;S0010-7824(20)30434-0.