Period swimwear looks like an ordinary swimsuit, with an absorbent layer built into the gusset. It’s designed to hold menstrual fluid while keeping water out. This guide is unsponsored, and we don’t recommend any brand.
How it works
Most designs combine an absorbent inner core with a water-resistant outer layer. The seal around the legs and waist matters, so a snug fit is important.
What’s known, and what isn’t
- Capacity claims vary widely. Brands state very different amounts, and those figures are their own.
- Evidence is limited. We found reviews and brand tests, including a hands-on test by Outdoor Swimmer, but no clinical studies or medical guidance comparing it to tampons or cups.
- Check the materials. Harvard Health advises checking that period panties are free of PFAS, and the same question is reasonable to ask here.
Before you swim
- Try it at home first. Wear it in the bath or shower, or on a light day, to check the fit.
- Start with lighter days, until you know how it works for you.
- Rinse it after swimming, then wash it according to the instructions.
- Bring a spare and a towel, for peace of mind.
What one hands-on test found
Outdoor Swimmer tried three products with a few testers. Two didn’t leak in its tests, including one worn on a heavy day in a bath. The third showed staining on medium-flow days, and the testers suggested it for light days or as back-up. This was a small test rather than a clinical study, the capacity figures came from the brands, and the magazine earns commission on purchases, so treat it as one useful report.
The products it describes hold around 10 to 15ml by the brands’ own figures, and one brand representative suggested using a cup as back-up for heavy flow on long swims. Periods usually involve about 20 to 90ml of blood in total, so capacity matters less for a short swim than for a long day out.
How it compares for swimming
| Period swimwear | Period cup | Tampon | |
|---|---|---|---|
| Worn | Outside the body | Inside the vagina | Inside the vagina |
| Reusable | Yes | Yes | No |
| Often suits | Light to medium days | Heavier days, or as back-up | Heavier days, or as back-up |
Questions to ask before you buy
- What capacity does the brand claim, and how was it tested?
- Does the brand state that the materials are free of PFAS, and is there independent testing behind that?
- How long does the brand say you can wear it in the water?
- Is the fabric resistant to chlorine, and does it offer UV protection if you swim outdoors?
- What are the washing instructions, and what does the returns policy say about swimwear?
If you’re often soaking through protection quickly, or need to use two products at once, that can be a sign of a heavy period and is worth mentioning to a GP.
Other options
For swimming on heavier days, a period cup or a tampon may suit you better. For daily wear, see period panties.