What an interesting question! It reminds me of conversations about what foods change the flavor of semen (the consensus seems to be pineapple juice.) But when it comes to pH, all the experts I spoke to agree - there’s nothing you can do that will be helpful in this regard. In fact, Ryan Cain PA-C, MPAS, cautions, “Apple cider vinegar and cranberry pills are a recipe for gastrointestinal distress.”
The experts also agree that it all comes down to good hygiene. Evelin Dacker, MD, says “Good hygiene includes regular washing as well as washing after any anal penetration before entering a vaginal canal. There is no real difference between antibacterial soaps and sensitive skin soaps but I recommend a mild, perfume free soap on any genitals.” She goes on to explain that, “this is especially true if the penis is uncircumcised, since the folds of the foreskin can hold extra bacteria which can be introduced into the vaginal canal through sex. ”
And Cain echoes this, “Showering regularly is a good start. Antibacterial soap is unnecessary and can disrupt the normal flora of the skin.”
With all this talk of showering, remember that it is possible to have too much of a good thing. Cain cautions, “Frankly, men and women’s genito-urinary systems are like self cleaning ovens. Over cleaning can be more harmful, sometimes allowing bacteria and yeast to take hold leading to chronic infections.”
If you’re wondering why we’re talking about pH, Samantha LeVine, ND, explains the science, “Semen is alkaline (higher pH) as a result of a combination of factors including contributions from several glands that surround the urethra and deposit components into the semen. Having an alkaline pH is normal for men.” And she goes on to say, “If this is bothering a woman’s vaginal or vulvar chemistry, your best bet is to withdraw prior to ejaculation and have her urinate right after sex.” And, of course, urinating right after sex is always a good preventative measure, even if you haven’t noticed any problems.
LeVine goes on to advise, “Some vulva-owners may want to alter their pH directly either as a preventive (say, using boric acid capsules intravaginally every week or so) or after intercourse. In addition, optimizing the flora of the vagina can help maintain healthy microbe balance. Occasional use of probiotics that are designed for women (specifically the species Lactobacillus reuteri and Lactobacillus rhamnosus) orally can be useful to maintain healthy tissue resilience. In addition, each woman’s needs are different, so have them consult their MD or ND if they’re noticing any issues with discharge, frequent UTIs, etc.”
When it comes to threesomes, sometimes barriers really are the way to go. “Vaginal to vaginal fluids could cause more imbalance than penis to vagina, since women who have sex with other women tend to have an increased risk of bacterial vaginosis (which is caused by pH shifts and imbalance).” Says Dacker.
To prevent unwanted fluid exchange, wearing condoms for penetration - and switching condoms when you’re switching partners - is the best way to make sure you’re not a vector for cross contamination. The same is true for switching from anal to vaginal penetration. If you’re using sex toys together, cover those with condoms as well.
Another fun option for threesomes is to have each partner wearing an internal condom. That way you can move back and forth between partners with ease. (And while lube makes everything better, it’s absolutely essential when using internal condoms.)
For hand sex, gloves can fill this role. You can even get different colors of gloves and color code so you can easily remember which hand goes with which partner.
Ultimately, it sounds like you’re already doing the number one thing you can to maintain everyone’s sexual health - talking. Keep lines of communication open so that everyone knows if something has changed, or if there are new or different risk factors to account for. And don’t forget to actively check in now and then. Sometimes people forget when there’s a change that might be significant.