Leakproof menstrual underwear that can be worn as an alternative to tampons and pads.


KNIX is one of the many brands of leakproof underwear on the market that advertises it can replace tampons and pads during menstruation. This is not only better for the environment, but it is also a potential option for women with FOP when limited arm mobility makes placing and removing tampons and pads impossible.

KNIX underwear has a high-tech lining that has a moisture-wicking “honeycomb” top layer that is chemical-free and composed of natural fabrics that resist the growth of bacteria and wicks away mosture to keep the skin dry. The super-absorbent liquid-lock inner layer locks in menstral liquid, sweat and small urine leaks, and a liquid-resistant outer layer prevents leaks from the underwear.

KNIX underwear comes in a variety of absorbancy options for use during lighter and heavier flow days. KNIX provides the following guidance as to how many teaspoons of liquid each style of underwear is capable of holding:

  • Leakproof: 1-3 teaspoons of light menstrual leaks and sweat
  • Super Leakproof: 4-8 teaspoons of average menstrual leaks and sweat
  • Cotton Super Leakproof Boxer Brief: 10 teaspoons of heavier menstrual leaks
  • Super Leafproof Dream Short:  12 teaspoons of heavier menstrual leaks
  • Regular Reusable Pads: 12 teaspoons of heavier menstrual leaks
  • Overnight Reusable Pads: 20 teaspoons of heavy menstrual leaks

KNIX offers sizes from XS to 4XL to provide size and fit options for all body types. KNIX Leakproof Underwear is also eligible for return or exchange within 30 days of delivery, and is machine-washable on cold.


While KNIX underwear is machine-washable, DO NOT use fabric softener or place them in the dryer as this will compromise the fabric and reduce the absorbancy. Cold wash and air dry is the recommended care.

Where to purchase

Knix website - Leakproof underwear

Here is an honest review of the underwear – they may not prevent all leaks on heavy days depending on your personal fit with the underwear and the severity of your menstrual cycle:


And a video on how to wash period underwear – do not use fabric softener or put in the dryer!