The feisty warning signs of an oncoming yeast infection can strike at any time: irritation, burning, discharge. This excessive buildup of microscopic fungi can flourish in any moist region—anuses, throats, genitals of both sexes—but most commonly takes root in a woman’s nether regions. Yeast can grow out of check when a person is stressed, has recently used antibiotics or has a weakened immune system. Persistent infections, however, know no health, race or age boundaries. In fact, about 75 percent of women suffer occasional yeast infections. For an unlucky 5 percent these itchy infections grace their private parts more than four times a year.
Many sufferers have devised creative home remedies for calming this vaginal fury. Some freeze yogurt into ice cube–size popsicles and insert them into their vaginas. Others swallow capsules of probiotics or douche with tea tree oil. Perhaps most unusual is an alternative therapy that uses a common culinary ingredient—garlic. But instead of ingesting the Allium, women insert it into their vaginas as aromatic suppositories for hours at a time. Do these old wives tales really work? And whether they do or not, can they be dangerous?
To get the medical perspective on such treatments, Scientific American spoke with Paul Nyirjesy, an obstetrician–gynecologist and director of the Drexel Vaginitis Center at Drexel University College of Medicine. He treats women with complicated and chronic vaginal problems, including recurrent yeast infections. He recently published a paper examining how a majority of women with such problems use alternative treatments—primarily out of desperation.
[An edited transcript of the conversation follows.]

What is your background in treating yeast infections?
I did a fellowship in infectious diseases about 20 years ago. I used that training to focus on seeing women with chronic vaginal problems. For the past 11 years, I've been the director of the Drexel Vaginitis Center. We see women with all sorts of complicated problems, including but not limited to recurrent yeast infections.
How common is it for a woman to try an alternative therapy at home before she goes to the doctor?
For women who have chronic vaginal problems, a majority of them—about two thirds—will try at least one form of alternative medication.
What are the most common types of alternative therapies that you’ve seen women try?
By far the two most common are going to be either yogurt or probiotic pills—usually taken orally, sometimes taken vaginally.
Is there any indication that these treatments might work?
Can these treatments make yeast infections worse?
They probably don’t make them worse; I don't think it really makes a difference. There have been a bunch of probiotic studies—most of them don't show any benefit at all. A few have shown potential benefit, but it's not totally clear that the studies didn't have flaws that might make the results questionable.
There’s a strong cadre of women on the Internet who swear that inserting a garlic clove into the vagina will clear a yeast infection. Do you think this method is helpful?
Almost 10 percent of the patients we see have tried garlic before they get to us. I'm biased, of course, because I'm seeing patients where things haven't worked. But I can't recall a single patient who told me that she used garlic and she thought it was helpful.
Do any scientific studies suggest that garlic may clear an infection?
I did a literature search and the only paper I found was a paper from The Iranian Journal of Nursing and Midwifery Research in December 2010. They compared a cream that had clotrimazole, a standard antifungal cream, to a cream that contained garlic and thyme. They found that the garlic and thyme cream was as effective as the clotrimazole cream. The problem was that if you looked at the actual results, it's hard to know which patients really got better. They didn't really have follow-up cultures. It's difficult to look at the paper and base any firm conclusions on it, other than the patients had a decrease in vaginal symptoms when they were using this cream.
Another study out of Australia looked at oral garlic. The group has been doing some pretty serious studies looking at alternative medications to treat vaginal infections. They did a small study looking at what oral garlic does to the growth of yeast in the vagina and they found that there was no impact. That was a well-done, randomized controlled trial.
Where did this remedy originate?
There is some information that there's a compound in garlic, called allicin, that is considered fungicidal. In the lab it looks as though it has antifungal activity. There have been some animal studies that look interesting. Theoretically it makes a lot of sense. But you don't know how much garlic you need or how effective it is. If you put a clove of garlic in your vagina, does it really treat what's going on in the vagina or is it just sitting there with all the active ingredients sitting in a clove of garlic?
Are there any risks associated with walking around with a garlic clove in the vagina?
Probably not. The main concern would be that if you put anything in your vagina, there's a chance you'll get irritation and burning from whatever you put in there.
Are there any alternative remedies that appear to actually work?
One remedy with a fair amount of data is boric acid. Boric acid has been around since the 1860s. It's the same thing you use to get rid of cockroaches. It's a very effective antifungal, and for some of the more resistant types of yeast infections we see it's actually the first line therapy.
How is it taken and where can you get it?
Boric acid is poisonous if taken by mouth. When I prescribe it, I usually have a compounding pharmacy mix it into 600-milligram capsules that patients use vaginally. There are patients who order gelatin capsules and boric acid, and they make it up themselves. My concern is I'm not sure they're necessarily getting the correct dose, which is why I like to get it mixed by a pharmacy. Studies have usually looked at a two- or three-week course of treatment.
Is boric acid as effective as prescription medications used to treat vaginal yeast infections?
For short-term treatments, probably. And for some of the more resistant yeast, it's actually better. There's a fair amount of literature showing that this is the way to go. If you look on the CDC [U.S. Centers for Disease Control and Prevention] guidelines for treating yeast infections, you'll see them talk about boric acid. If you read the guidelines by the American Congress of Obstetricians and Gynecologists, they talk about it as well.
Can boric acid be toxic if used at too high of a dose?
If you use too much of it, yes. But if it's a little bit off from 600 milligrams, probably not. Just like any other thing you put in your vagina, the most common side effects are going to be burning and irritation. It's actually in general pretty well tolerated. And the other big thing is to keep it out of reach of little children and pets.
Do you think women have enough options to get correct medical treatment?
The treatments available over the counter are comparable in terms of efficacy to what you can get with a prescription. Over-the-counter Monistat treatment is as good for an isolated episode as one pill of fluconazole, which is the standard for a single yeast infection episode. I think the issue is that there are loads of women out there self-treating for yeast infection who don't have it at all. The data is that a lot of women don't really know when they have a yeast infection. The good news is that the treatments available have a very low risk to them. They probably, for the most part, aren't doing themselves significant harm. But some of the treatments are probably not the right treatments.
What is the best course of treatment for a woman with a yeast infection that simply won’t go away?
The first thing is to get a culture to identify which type of yeast is causing the infection. In most women it's going to be Candida albicans, which is the most common cause of yeast infections in general and also the most common cause of recurrent yeast infections. The approach that seems to work the best right now is putting patients on maintenance therapy. For six months they take a pill of fluconazole once a week. It's very effective—about 90 percent of people do great during that six-month period of time. About 10 percent may have occasional breakthroughs, where they get an occasional infection while on treatment. The issue is that about half the time, once patients stop treatment, the infection comes back.
Why do you think that a lot of women resort to these alternative therapies before seeing a doctor?
I think a lot of times they don't feel that doctors are going to have a good answer for them. Unfortunately, many doctors aren't aware of recommendations for maintenance therapy. Another thing is that alternative remedies sound great. You don't have to go in, you don't have to be evaluated. There's a perception that if it's a natural remedy, it's going to be completely safe and there won't be any side effects. There's this perception that natural is going to be better because it helps your body take care of the problem.