Readers of this blog are already aware that their vaginas are at their best when they are on the acidic side. Vaginal flora is healthy, bacterial overgrowth is at a minimum, and any foreign bodies that want to pass through are firmly discouraged. Semen and douching can increase pH, douching especially so since the liquid used to douche not only has a relatively high pH but flushes out normal, good bacteria.

If there are substances that increase vaginal pH, might other substances decrease vaginal pH and thus encourage the growth of normal flora?

RepHresh thinks so. RepHresh is a company that makes pH-balancing gels and cleansers for your ladyparts. Recently, they started carrying a new product, RepHresh Brilliant, which is a pH-balancing tampon (hat tip to my undergraduate Sophia Bodnar for being the first to tell me about it). They claim that menses increases pH, and thus a tampon that decreases pH will keep bacterial overgrowth in check. The RepHresh Brilliant tampon contains strips of material that slowly release lactic acid and citric acid as they are saturated with menstrual fluid.

It certainly sounds like a good idea. Women in industrial and post-industrial environments menstruate far more often than we probably did under ancestral conditions, due in part to an energy surfeit (you know, eating too much chocolate while sitting at a desk, which is exactly what I was doing while drafting this post) and in part due to modern reproductive decisions (you don’t menstruate so much if you’re pregnant or breastfeeding all the time) (Strassmann 1997). So about 400 times in our lives, for several days at a time, we have a higher pH (somewhere between a 5.3-6.6 depending on the day according to Wagner and Ottesen 1982) than is ideal for housing beneficial vaginal flora.

But I want to know if this fancy tampon works. 1) Does it reduce pH, 2) does it do so without side effects, and 3) does it have an effect on vaginal flora?

Tl;dr version:1) yes, 2) probably, and 3) not sure.

RepHresh’s own research on the topic

A single paper tests the efficacy and safety of the RepHresh Brilliant tampon, and you can find a copy on the RepHresh site (Brzezinski et al. 2004). The authors found that participants who used the test-tampon (the one with strips that release lactic and citric acid) did not have significantly higher vaginal pH during menses (p = 0.0518), while participants who used a regular tampon did (p = 0.0011). Saying that first result isn’t statistically significant is adhering to the 0.05 alpha without honoring the spirit of the 0.05 alpha – it is not statistically significant but in a way that makes one question the meaning of statistical significance. (If you are new to statistics, usually a p-value that falls below 0.05 is considered significant, so a p-value of 0.0518 is pretty darn close, and in fact most people would drop those last two places and round to the hundredth, rendering that analysis p = 0.05, or statistically significant.) All that said, the difference between groups in intra-menstrual pH is statistically significant (p = 0.0025). And lowering menstrual pH by 0.5 isn’t bad.

Further, according to Brzezinski et al (2004), no participants complained of vaginal irritation, which would be my big worry about an acid-producing tampon. And no participants in either group had abnormal vaginal flora during the study.

So, yay! Acid-increasing tampons for everyone! Kinda.

Nits to pick

First, the authors of this study did not use the gold standard method for assessing vaginal irritation or endothelial disruption, which is a colposcopy, or visual assessment of the vaginal tissue. Instead, the authors relied on self-report. Minor issues, or ones that could develop with repeated use over many cycles, would be caught in a longitudinal study that used this method. But this study only assessed side effects and pH reduction in a single cycle. And as far as I can tell, it is the only published study on the topic.

The second issue to consider is that all twenty eight participants had normal vaginal flora. The coincidence of all participants being perfectly healthy makes me wonder if a small sample size caught an abnormal number of normal women, or if they needed more rigorous testing of the bacterial swabs. But the study authors provide no detail about how they determined this or whether they assessed absolute and relative quantities of different bacteria that comprise normal flora. So, the normal flora in every single subject could just be that all twenty eight women were very healthy, but in every other study I read in preparing for this post, there were always a significant minority of participants who had or developed abnormal flora. I just wish the authors had provided more detail here.

Finally, this research was funded by Rostam Ltd Israel, a corporation that makes tampons. I did a little digging to try and figure out the relationship between Rostam and RepHresh. Rostam was bought by Albaad Massuot Yitzhak Ltd in 2010. Yet RepHresh has an article about the Rostam Ela tampon in the Wall Street Journal on the website from 2004. So my best guess (and someone with more business savvy than me could probably figure this out) is that RepHresh bought the Ela tampon from Rostam some time between 2004 and 2010, and is now marketing it as RepHresh Brilliant. Either way, part of the funding for the research was from a corporation invested in seeing the tampon gain FDA approval in the US. The 2004 article that RepHresh has on its site (scroll to the “Articles” and click the link for the pdf) explains that the testing for this tampon was simply to demonstrate it is as safe as effective as any regular tampon, since it is being categorized as a medical device.

I’m not worried about the lactic acid, since that is a product of Lactobacilli, which is not only present in normal vaginal flora but particularly good for the ladyparts (McLean and Rosenstein 2000; Onderdonk et al. 1986; Valore et al. 2002). But I am worried about the citric acid, since it produces moderate irritation and damage to the epithelium, and increases permeability and absorption rates when used to enhance drug delivery (Richardson et al. 1989). Maybe it’s shouldn’t be concerning in the particular way it is released in the RepHresh Brilliant tampon. I honestly don’t know.

I certainly am happy to see a company taking a woman’s actual vaginal pH into account in the making of their products. Give the tampon a try if you are so inclined, and let me know how it goes. I think I’m going to just let my vagina regulate itself, since vaginal flora repopulates naturally and quickly after menses on its own (Keane et al. 1997; Onderdonk et al. 1986; Wagner and Ottesen 1982).


Brzezinski A, Stern T, Arbel R, Rahav G, and Benita S. 2004. Efficacy of a novel pH-buffering tampon in preserving the acidic vaginal pH during menstruation. International Journal of Gynecology and Obstetrics 85(3):298-300.

Keane F, Ison C, and Taylor-Robinson D. 1997. A longitudinal study of the vaginal flora over a menstrual cycle. International Journal of STD and AIDS 8(8):489-494.

McLean N, and Rosenstein I. 2000. Characterisation and selection of a Lactobacillus species to re-colonise the vagina of women with recurrent bacterial vaginosis. J Med Microbiol 49:543-552.

Onderdonk A, Zamarchi G, Walsh J, Mellor R, Munoz A, and Kass E. 1986. Methods for quantitative and qualitative evaluation of vaginal microflora during menstruation. Applied and Environmental Microbiology 51(2):333-339.

Richardson JL, Minhas PS, Thomas NW, and Illum L. 1989. Vaginal administration of gentamicin to rats. Pharmaceutical and morphological studies using absorption enhancers. International Journal of Pharmaceutics 56(1):29-35.

Strassmann BI. 1997. The biology of menstruation in Homo sapiens: Total lifetime menses, fecundity, and nonsynchrony in a natural-fertility population. Current Anthropology 38(1):123-129.

Valore E, Park C, Igreti S, and Ganz T. 2002. Antimicrobial components of vaginal fluid. Am J Obstet Gynecol 187:561-568.

Wagner G, and Ottesen B. 1982. Vaginal physiology during menstruation. Annals of Internal Medicine 96(Part 2):921-923.