If you search on the internet for GYN problems attributed to thong underwear you can find sites which claim thongs increase the risk for urinary tract infections, vaginal infections, clitoral pain, and irritation of hemorrhoids. Is there research which can validate such claims? What about the claims that a type of fabric (e.g. cotton vs synthetic) can make a difference if one wears a thong? In the interest of science, I went on a mission to answer such questions.
Some 93% of urinary tract infections (UTIs) in women are caused by the enteric (bowel) bacteria called E. Coli. Theoretically, any mechanical movement which moves stray E. Coli from the anal opening toward the urethra should increase risk of UTIs. Thongs with their positioning in the gluteal fold would seem ideally suited to providing transit opportunities for E. Coli. Yet there is no published data which suggests that UTIs are more frequent in thong wearers. Looking back to earlier studies one can find that, despite popular opinion, there is not association between tight pants or other restrictive clothing and UTIs (Remis, Am J Epidemiol,1987; Foxman, Am J Pub Health, 1985). Overwhelmingly the strongest predictive factors for UTIs in younger women are: increased frequency of intercourse, use of diaphragm + spermicide, spermicide use, and past history of other UTIs (Hooton, N Engl J Med, 1996).
E. Coli can also be found in the vagina. Yet it is not a common cause for vaginal infections. As with UTIs one of the easier ways for bowel bacteria to get into the vagina is via intercourse. Perhaps the most important preventative measure is to clean well after bowel movements (always wiping away from the vagina/urethra) – and never have sex (just kidding).
As anyone who has ever used thongs can attest, there is a wide range in fit. The strap can be thick or thin, and the overall fit can be loose or what one women’s magazine called “atomic buttocks’ floss.” It may be true that tight thongs can cause irritative pressure to the clitoris or to other friction sensitive conditions such as lichen sclerosus or external hemorrhoids. Alas, no one has published any data about the incidence of such problems.
Surprisingly, researchers have done experiments about the type of fabrics used in undergarments. Comparing 100% cotton to 100% acrylic, under resting and exercise conditions, both materials were found to be equal in their wicking abilities. Only in the subjects who perspired most heavily was there a difference. Cotton accululated 71 grams of sweat compared to 46 grams in the acrylic (Rissanen, Ann Physiol Anthropol, 1994).
When types of underwear material were correlated to frequency of UTIs, Foxman and Frerichs (1984) found cotton panty use linked to increased UITs. When women with documented UTIs were asked about underwear habits over the preceding month, both initial and recurrent UTI sufferers stated cotton rather than synthetic panty use.
The above fact illustrates the scientific principle, “association does not always prove causation.” Rather than cotton underpants causing increased UTIs, perhaps cotton is chosen by women who are at risk for getting more bladder infections. By the same logic, before we condemn thong underwear, one would need to take into account the individual GYN history of the woman wearing the thong. In some instances the thong may be wrong, in others – no problem.