Does Body Odor Change During Your Menstrual Cycle?What Studies Found

If your underarms seem to smell different in the days before your period or around ovulation, you’re not imagining that your body changes across the month. Whether the smell changes is a harder question.

The early studies

Most of the research asked a narrow question: do men rate women’s scent differently near ovulation?

Study	Design	Finding
2001	Women wore a T-shirt for 3 nights near ovulation and again later in the cycle1	Men rated the near-ovulation shirts more pleasant1
2012	Scent samples on a high- and a low-fertility day, ovulation confirmed by hormone tests2	Men told them apart 61% of the time and preferred the high-fertility sample 56% of the time, where 50% is chance2

Those differences were small.

The most careful test

A 2024 study³ tracked naturally cycling women’s underarm odor over 10 days around ovulation, confirmed with urine ovulation tests and saliva hormone levels.³ 91 men rated the samples, and researchers ran chemical analysis on 143 samples from 16 women.³

The result: no evidence that men preferred the scent of fertile women, and no link between the chemicals in underarm odor and fertility.³

It used unfamiliar raters and didn’t ask whether women notice changes in their own smell.³ So the question you may care about, “Do I smell different before my period?”, hasn’t been studied well.

What’s known

UK guidance lists hormonal changes among the things that can make body odor worse, alongside exercise and hot weather.⁴ A change from your usual smell is worth mentioning to a doctor.⁴

Some smells that seem cycle-related come from elsewhere: see vaginal odor causes and breath across the cycle. Your own nose can also mislead you; see can you smell your own body odor?

Tracking your own pattern

1. Note your cycle day alongside any smell you notice, for two or three cycles.
2. Write down sweat too. Smell and the amount of sweat can change separately.
3. Keep products steady while you track, so a new deodorant doesn’t muddy the picture.

Try: “My underarm odor seems much stronger in the week before my period, and it’s been going on for months. Is there anything hormonal worth checking?”

Arms Up covers this in Chapter 8, “Still Smell After a Shower?,” in a section called “Hormones, Age, and Your Usual Smell.” Its Fresh Log has a cycle-day column, and two or three cycles of notes will tell you more about your own pattern than the studies can. See the book.