Menstrual apps promise health benefits without convincing evidence

Clinical takeaway: Ask patients who track or cycle sync about exercise and contraception, and evaluate irregular, missing, or painful periods rather than attributing them to the cycle. 

Millions of people use menstrual tracking apps, and many turn to them to understand their symptoms and to talk with their clinicians. Many of the apps now go further, marketing cycle syncing, which matches exercise and nutrition to estimated menstrual phases, as a route to better health and performance. Technology companies and social media promote the practice widely to women and girls. 

The apps generally estimate cycle phase by counting forward from the first day of bleeding, a method that is imprecise without hormonal confirmation. A new analysis from an interdisciplinary group of scholars challenges the apps' health claims and warns that their risks may outweigh the benefits. 

The authors argue that neither digital menstrual tracking nor cycle syncing has been convincingly shown to improve health or performance. Decades of sports science research found no generalizable effect of phase on performance, with effects at most trivial and individualized. A 2024 study of elite rugby players found little relation between phase and performance tests. 

Counting days cannot reliably detect phase even in people with predictable bleeding, because ovulation timing varies and anovulatory cycles are common. Basal body temperature and luteinizing hormone changes can improve the estimates, but most apps don't measure phase. Cycle changes can point to other conditions, but simple apps can't diagnose them. They miss the early changes of relative energy deficiency in sport, a shortened luteal phase and anovulation. Nor can they identify the causes of painful periods, such as endometriosis, without examination or imaging. 

Some cycle syncing advice limits exercise to low-intensity activity for much of the cycle, which conflicts with guidance for weekly moderate or vigorous activity. Some proponents urge stopping hormonal contraceptives to follow so-called natural cycles, which could raise the risk of unintended pregnancy. Tracking may also lead users to attribute valid symptoms to the cycle and overlook rest, nutrition, and exercise. Some apps sell menstrual data under uneven regulation, which may expose users to misuse by employers, corporations, or the state, with added risks where abortion is criminalized. 

The authors cite several proposals for reducing the risks of tracking: stronger protections for consumer and employee data, transparent labeling so users know how their data are used, and clinicians recommending apps only when they meet stringent standards. Health communication tailored to the social media platforms where users meet cycle syncing content may also help counter misleading narratives about hormones and health. 

"These apps have the potential for widespread impact on the wellbeing of women and girls," write Katharine Lee, PhD, assistant professor of anthropology at Tulane University, and colleagues. "Yet, the evidence that these digital tools can actually help in the management of menstrual conditions, boost health, and provide insights into exercise and nutritional needs is lacking." 

Source: Lee KMN, et al. (2026 Sep 30) BMJ. Digital menstrual tracking risks creating more harm than benefit