there are 2 good reasons to learn a bit about the causes of vaginal yeast infections. first, if you have recurring yeast infections, you can figure out what's causing them and then work to prevent them, rather than just working to kill the yeast every time they take over. second, if you know what kinds of things cause you to get yeast infections, you can be alert for symptoms and treat them early on with the generally-milder do-it-yourself remedies, rather than bombarding your body with drugs.

vaginal yeast infections are caused by Candida albicans, which, along with a few types of bacteria, are normally present in relatively small numbers in your crotch. sometimes the yeast multiply rapidly and take over, causing a full-fledged yeast infection, or, in the heart-warming terminology of the medical establishment, candidiasis or monilia. this can be due to a change in the vaginal environment, injury, sexual transmission, or HIV. common environmental disruptions that favor yeast include increased pH, increased heat and moisture, allergic reactions, elevated sugar levels, hormonal fluxes, and reductions in the populations of bacteria that are normally present. these can generally be traced to a few categories of culprits:

antibiotics are probably the leading cause of vaginal yeast infections in american wimmin, and are a great example of the important principle that by using technology to solve problems, we create other problems. say you take an antibiotic to cure your sinus infection. the antibiotic kills the unwanted bacteria in your sinuses, but can also kill the "good" bacteria in your crotch, upsetting the balance of your vaginal ecosystem, allowing the yeast to take over. (antibacterial deodorant soap can have the same effect.) most wimmin have problems with only a few types of antibiotics, or with prolonged antiobiotic treatment. others get yeast infections every time they take antibiotics. unfortunately, i know of no way of preventing an antibiotic-induced yeast infection; you just have to treat it once it starts.

clothing: crotch yeasties flourish in non-cotton, tight, or dirty clothes that trap heat and moisture. no doubt Xena, Warrior Princess, gets infections all the time from that leather underwear. your absolutely best bet is to wear a skirt with no underwear or tights, and definitely avoid pantyhose. if you've ever had an urge to go for that sexy thigh-high stocking look but have been too shy, here's the excuse you've been looking for. and if you do wear underwear, your safest bet is unbleached, undyed cotton underwear and breathable clothes. it's a good idea to change your underpants regularly, like maybe once a day. if at all possible, don't sleep in underwear; if you do, put on clean stuff. yeast can live in your underwear, so be sure to wash it well, particularly during and after a yeast infection. some medical types think that when you have a yeast infection, you should wash and dry your underwear and then iron it or throw it in the microwave on high for 5 min to kill the yeast. on the other hand, check out this testimonial: "I wanted to alert your readers that putting underwear in the microwave for 5 minutes is a VERY BAD IDEA... I went off to finish my nightly ablutions, leaving the underwear nuking away. I came back to a little black melted pile and an incredibly difficult to clean microwave." there you have it. i personally am going to stick to ironing.

chemicals, such as inks, dyes, and perfumes, can upset the balance in your crotch or trigger allergic reactions that lead to yeast infections. the classic example is commercial douches, which have no benefits and are definitely harmful to the vaginal environment and your health. you know those odor-causing bacteria that their products help you get rid of? well, they're the same bacteria that kill the yeast in your crotch! on top of that, soaps are not only disruptive to the vaginal environment, but can damage your mucus membranes. you should never soap your crotch. but there are other, less obvious sources of nasty chemicals. for example, i've had serious problems with those nasty colored, perfumed toilet papers, like Charmin; 5 days of that and i am yeast central. if you think that's your problem, try an unscented, undyed toilet paper, like Scott. even better, use a recycled, unbleached eco brand. similarly, some laundry detergents and fabric softeners have allergenic dyes and perfumes; i invariably get yeast infections from underwear washed in Liquid Tide, and a friend of mine gets them from underwear washed in Wisk. again, try an eco brand, or something like Arm & Hammer fragrance free detergent. additives in bubble baths or bath salts, scented tampons or sanitary pads, or (heaven forbid) feminine deodorant sprays, can similarly trigger yeast infections.

condoms can promote yeast infections in two different ways. first, a lot of condoms come packaged with a lubricant that contains nonoxynol-9, a spermicide that may kill the HIV virus. a friend of mine has been insisting for years that she gets a yeast infection every time she comes in contact with the stuff. sure enough, several recent studies have shown that nonoxynol-9 is linked to yeast infections. if you suspect this is your problem, try using a condom that doesn't have a spermicidal lubricant, and use a different spermicide or additional barrier protection. condoms can also cause yeast infections if you are allergic to latex, although this is less common. if this is the case, don't give up hope on practicing safer sex. you may want to try some of the newer plastic (polyurethane) condoms for boys or girls.

diet: some people say that cutting down on yeast-containing foods helps lessen the intensity or frequency of vaginal yeast infections. i don't understand how this could matter, because the kind of yeast that's found in foods like bread or beer is not at all like the yeast found in the vagina. but hey, it can't hurt, and it might help. similarly, many people believe that high levels of sugar in your diet can contribute to yeast infections, presumably by elevating sugar levels in your urine, giving the yeast more food. i can't see how this could happen in a healthy person, but if you think it's a problem for you, cut down on your sugar and alcohol intake. it is clear that wimmin with poorly controlled diabetes get frequent yeast infections, precisely because of sugar in the urine. if you have frequent yeast infections and have other symptoms of diabetes, like you're always thirsty and you have to urinate often, go see a doctor. finally, most advocates of dietary causes also list caffeine as a factor. again, i don't understand the connection and personally can't imagine my life without caffeine, but it's up to you.

hormones, both naturally-occurring and artificially introduced, can affect yeast. for example, pregnant wimmin are particularly prone to yeast infections. many wimmin taking contraceptive pills experience regular yeast infections as their hormone levels fluctuate. i was on the pill for a while, and got a yeast infection every single month, right before my period. also, whether or not you're on the pill, yeast generally doesn't like the pH of menstrual blood, so mild yeast infections will often go away during your period. don't count your chickens, though, because the yeast will sometimes rebound as soon as your period is over. likewise, steroids used in the treatment of disorders like arthritis, asthma, or lupus can contribute to yeast infections.

injury to the vulvar or vaginal membranes can lead to a yeast infection. this is almost always due to too much friction with not enough lubrication. in other words, if you or someone else is rubbing something in your vagina or against your crotch, be sure you're really wet. and if you're not wet enough on your own, don't be shy about adding lubrication, but be smart about what you use: oil-based products, like vaseline, break down latex; and even non-oily handcreams contain dyes and perfumes that can cause yeast infections! spit works, but only for a bit, and some people think it can lead to yeast infections. your best bet is to use a product designed as a sex lubricant, like K-Y (cheap but nasty), or better yet, Astroglide, Wet, or Probe (more expensive, but slipperier and longer-lasting; check your local pharmacy to see what they have).

sexual transmission: Candida can be transmitted between people by direct contact, and so can actually be a sexually-transmitted disease. lesbian partners are particularly susceptible to passing yeast infections back and forth, so if you or your lover has an active infection you should be extra-careful to follow the safer sex guidelines: wash your hands or change your gloves in between touching your own crotch and your partner's, and keep your toys clean clean clean. and you should be aware that men can get yeast infections, often without symptoms. it's not uncommon for a yeast-infected woman who has unprotected sex with a man to infect her lover, treat her own infection, and then get reinfected next time she has sex with him. if you think your male lover might have a yeast infection, get him some treatment, and practice safe sex at least until both of you are sure that your infections are gone.

weakened immune system: wimmin with compromised immune systems due to HIV or Lyme disease are extremely prone to suffering from yeast infections. in addition to vaginal yeast infections, such people are particularly susceptible to thrush, a yeast infection of the throat, or esophageal yeast infections. the web contains several good fact sheets on candida infections in people with HIV, like those from Project Inform, the Community Aids Treatment Exchange / Reseau communautaire d'info-traitements sida, and the AIDS Treatment Data Network.