Possibly because they are so common, women often self diagnose them and self-treat with over-the-counter products.

But self-diagnosis may be a misdiagnosis. A handful of other vaginal infections, such as bacterial vaginosis (BV), the most common cause of vaginitis in the U.S., and trichomoniasis, a sexually transmitted infection, cause similar symptoms. BV and trichomoniasis may also be associated with serious reproductive health conditions and may lead to problems during pregnancy and after delivery.

Vaginal yeast infections may cause the following symptoms:

• Vaginal itch and/or soreness.

• A thick cheese-like vaginal discharge, which may smell like yeast. A fishy odor is a symptom of BV, not of a yeast infection. The vagina normally produces a discharge that is usually described as clear or slightly cloudy, non-irritating, and having a mild odor.

• A burning discomfort around the vaginal opening, especially if urine comes into contact with the area.

• Pain, dryness or discomfort during sexual penetration.

Contact your health care professional if you have any of these symptoms.

During the normal menstrual cycle, the amount and consistency of vaginal discharge varies. At one time of the month, you may have a small amount of a very thin or watery discharge, while another time of the month the discharge may be thicker. These variations are normal. The normal mid-cycle discharge is slippery.

To diagnose your vaginal symptoms, your health care professional will perform a gynecological examination and check your vagina for inflammation and abnormal discharge. A sample of the vaginal discharge may be taken for laboratory examination under a microscope, or for a yeast culture, a test to see if candida fungi grow under laboratory conditions. Looking under a microscope also helps rule out other causes of discharge such as BV or trichomoniasis, which require different treatment.

Antifungal medications are used to treat yeast infections. In the past, these medications were available by prescription only following an examination with a health care professional.

Today, antifungal medications are available in various over-the-counter (OTC) preparations. They include:

• butoconazole (Femstat 3)

• terconazole (Terazol)

• tioconazole (Monistat-1, Vagistat-1)

• miconazole (Monistat 7)

• clotrimazole (Gyne-Lotrimin 3)

Differences among the various OTC medications now available include the length of treatment indicated, preparation type and cost. The shorter course of treatment is more convenient but often more expensive. Prescription antifungal treatments also are available.

In general, it's acceptable to use OTC antifungal medication to self-treat your symptoms if you've had a yeast infection diagnosed by a health care professional before and you are now experiencing the same symptoms.

However, if you meet any of the following circumstances, do not self-treat. Instead, contact a health care professional for guidance.

• You've never had a yeast infection before.
• You have a fever and/or abdominal pain.
• Your vaginal discharge is foul-smelling.
• You are diabetic, HIV-positive, pregnant or nursing.
• You used an over-the-counter yeast treatment but your symptoms have not gone away or they returned almost immediately.

If you take medication to treat a yeast infection--OTC medication or prescription medication--be sure to take the full course of the prescription. Don't stop using it, even if you begin to feel better.

If your symptoms don't respond, or return shortly after they'd cleared up, consult your health care professional. Don't just try a different over-the-counter treatment; your symptoms may not be caused by yeast.

Studies find about a 50 percent error rate in self-diagnosis of yeast infections. Thus, if you think that you have a yeast infection, there's a one in two chance you're wrong. If symptoms persist for more than 48 hours after self-treating with OTC medicine, or if they return promptly, see your health care professional.

Yeast infections also may clear up without any treatment. However, there is a small chance that these infections may lead to more serious pelvic infections when left untreated.

Side effects of OTC medications for yeast infections are generally minor and include burning, itching, irritation of the skin and an increased need to urinate. However, as with any medication, more serious side effects are possible, though rare, and may include hives, shortness of breath and facial swelling. Seek emergency treatment immediately if any of these symptoms occur.

Antifungal medications may damage condoms and diaphragms, so if you're using such a medication, take other precautions to protect against pregnancy and sexually transmitted diseases. Also, don't use tampons while treating yeast infections with medication inserted into the vagina.

If you see a health care professional, he or she may prescribe a single dose of oral fluconazole (Diflucan) or a generic equivalent, although this treatment is not recommended during pregnancy. Also, do not take fluconazole if you are taking cisapride (Propulsid) because this drug combination could cause serious, even fatal, heart problems. In rare cases, fluconazole has also caused severe skin rash, sometimes resulting in death. Again, notify your health care professional immediately if you develop a rash while taking fluconazole. Other, less serious side effects may be more likely to occur. These include:

• diarrhea

• headache

• dizziness

• fatigue

• itching

There have been reported drug interactions between warfarin, an anticoagulant (blood thinner) medication and topical miconazole nitrate products (such as Monistat 7) and oral fluconazole (Diflucan). Additionally, fluconazole may cause liver damage in rare instances, particularly in conjunction with alcohol use. Discuss all the medications you may be taking when you discuss your symptoms with your health care professional.

If you have a yeast infection, your sexual partners do not need to be treated. However, if a male sex partner shows symptoms of candida balanitis --redness, irritation and/or itching at the tip of the penis--he may need to be treated with an antifungal cream or ointment.

Medications cure 80 to 90 percent of vaginal yeast infections within two weeks or less, often within a few days in the case of less severe infections.

Some women prefer home remedies to antifungal medication, such as yogurt containing lactobacillus cultures. The yogurt is applied with an applicator or as a douche. However, there are no studies on the effectiveness of this treatment.

Medical experts are still trying to determine the most effective way to treat recurrent vulvovaginal candidiasis (RVVC). Currently, most health care professionals treat RVVC with two weeks of intensive medication, followed by up to six months of a lower maintenance dose medication. Your health care professional may recommend treating your partner if you experience RVVC, since researchers don't know what causes RVVC.