A vaginal yeast infection is a fungal infection that causes irritation, discharge and intense itchiness of the vagina and the vulva — the tissues at the vaginal opening. It's a type of vaginitis, or inflammation of the vagina.

Vaginal yeast infection (also called vaginal candidiasis) affects up to 3 out of 4 women at some point in their lifetimes. Many women experience at least two episodes.

Although a vaginal yeast infection isn't considered a sexually transmitted infection, you can spread the fungus through mouth to genital contact. Medications can effectively treat vaginal yeast infections. If you have recurrent yeast infections — four or more within a year — you may need a longer treatment course and a maintenance plan.

Yeast infection symptoms can range from mild to moderate and include:

  • Itching and irritation in the vagina and the tissues at the vaginal opening (vulva)
  • A burning sensation, especially during intercourse or while urinating
  • Redness and swelling of the vulva
  • Vaginal pain and soreness
  • Vaginal rash
  • Watery vaginal discharge
  • Thick, white, odor-free vaginal discharge with a cottage cheese appearance

Complicated yeast infection

You might have a complicated yeast infection if:

  • You have severe symptoms, such as extensive redness, swelling and itching that leads to tears or cracks (fissures) or sores
  • You have four or more yeast infections in a year
  • Your infection is caused by a type of candida other than Candida albicans
  • You're pregnant
  • You have uncontrolled diabetes
  • Your immune system is weakened because of certain medications or conditions such as HIV infection

When to see a doctor

Make an appointment with your doctor if:

  • This is the first time you've had yeast infection symptoms
  • You're not sure whether you have a yeast infection
  • Your symptoms don't disappear after treating with over-the-counter antifungal vaginal creams or suppositories
  • You develop other symptoms

The fungus candida causes a vaginal yeast infection. Your vagina naturally contains a balanced mix of yeast, including candida, and bacteria. Lactobacillus bacteria produce acid, which prevents yeast overgrowth. That balance can be disrupted and lead to a yeast infection. Too much yeast in your vagina causes vaginal itching, burning and other classic signs and symptoms of a yeast infection.

Overgrowth of yeast can result from:

  • Antibiotic use, which decreases lactobacillus bacteria in your vagina and changes the pH of your vagina
  • Pregnancy
  • Uncontrolled diabetes
  • Impaired immune system
  • Taking oral contraceptives or hormone therapy, which increases estrogen levels

Candida albicans is the most common type of fungus to cause yeast infections. Sometimes, other types of candida fungus are to blame. Common treatments usually cure a Candida albicans infection. Yeast infections caused by other types of candida fungus can be more difficult to treat, and need more aggressive therapies.

A yeast infection might happen after certain sexual activities, especially oral-genital sexual contact. However, a yeast infection isn't considered a sexually transmitted infection. Even women who aren't sexually active can develop yeast infections.

Factors that increase your risk of developing a yeast infection include:

  • Antibiotic use. Yeast infections are common in women who take antibiotics. Broad-spectrum antibiotics, which kill a range of bacteria, also kill healthy bacteria in your vagina, leading to overgrowth of yeast organisms.
  • Increased estrogen levels. Yeast infections are more common in women with an increased estrogen level. This can include women who are pregnant, or those who are taking high-dose estrogen birth control pills or estrogen hormone therapy.
  • Uncontrolled diabetes. Women with diabetes who have poorly controlled blood sugar levels are at greater risk of yeast infections than women with well-controlled diabetes.
  • Impaired immune system. Women with lowered immunity — such as from corticosteroid therapy or HIV infection — are more likely to get yeast infections.
  • Sexual activity. Although yeast infections aren't considered sexually transmitted infections, sexual contact can spread the candida fungus.

If you've been treated for a yeast infection in the past, your doctor may not need to see you and may prescribe a treatment over the phone. Otherwise, you'll likely see your family doctor or gynecologist to treat your condition.

What you can do

Here's some information to help you prepare for your appointment and know what to expect from your doctor.

  • Make a list of any symptoms you've had and for how long.
  • Make note of key medical information, including any other conditions for which you're being treated and the names of any medications, vitamins or supplements you're taking.
  • Avoid using tampons or douching before your appointment so that your doctor can assess any vaginal discharge you have.
  • Make a list of questions to ask your doctor, putting the most important ones first in case time runs short.

For a yeast infection, some basic questions to ask your doctor include:

  • How can I prevent yeast infections?
  • What signs and symptoms should I watch out for?
  • Do I need to take medicine?
  • Does my partner also need to be tested or treated?
  • Are there any special instructions for taking the medicine?
  • Are there any over-the-counter products that will treat my condition?
  • What can I do if my symptoms return after treatment?

During your appointment, don't hesitate to ask other questions as they occur to you.

What to expect from your doctor

Your doctor is likely to ask you a number of questions, such as:

  • What vaginal symptoms do you have?
  • Do you notice a strong vaginal odor?
  • How long have you had your symptoms?
  • Have you ever been treated for a vaginal infection?
  • Have you tried any over-the-counter products to treat your condition?
  • Have you recently taken antibiotics?
  • Are you sexually active?
  • Are you pregnant?
  • Do you use scented soap or bubble bath?
  • Do you douche or use feminine hygiene spray?
  • What medications or vitamin supplements do you regularly take?

To diagnose a yeast infection, your doctor may:

  • Ask questions about your medical history. This might include gathering information about past vaginal infections or sexually transmitted infections.
  • Perform a pelvic exam. Your doctor examines your external genitals for signs of infection. Next, your doctor places an instrument (speculum) into your vagina to hold the vaginal walls open to examine the vagina and cervix.
  • Test a sample of vaginal secretions. Your doctor may send a sample of vaginal fluid for testing to determine the type of fungus causing the yeast infection. Your doctor may be able to prescribe more effective treatment for recurrent yeast infections by identifying the type of fungus causing the infections.

Yeast infection treatment depends on whether you have an uncomplicated or a complicated infection.

Uncomplicated yeast infection

For mild to moderate symptoms and infrequent episodes of yeast infections, your doctor might recommend:

  • Short-course vaginal therapy. Antifungal medications are available as creams, ointments, tablets and suppositories. An antifungal regimen that lasts one, three or seven days will usually clear a yeast infection. A number of medications have been shown to be effective, including butoconazole (Gynazole-1), clotrimazole (Gyne-Lotrimin), miconazole (Monistat 3), and terconazole (Terazol 3). Some of these are available by prescription only, while others are available over-the-counter. Side effects might include slight burning or irritation during application. You may need to use an alternative form of birth control. Because the suppositories and creams are oil-based, they could potentially weaken latex condoms and diaphragms.
  • Single-dose oral medication. Your doctor might prescribe a one-time, single oral dose of the antifungal medication fluconazole (Diflucan). Or, you may take two single doses three days apart to manage severe symptoms.
  • Over-the-counter treatment. Over-the-counter antifungal vaginal suppositories and creams are effective for many women, and these are a safe choice during pregnancy. Treatment usually lasts from three to seven days.

Make a follow-up appointment with your doctor if symptoms don't resolve after treatment, or if they return within two months of treatment.

Complicated yeast infection

Treatment for a complicated yeast infection might include:

  • Long-course vaginal therapy. A treatment regimen of azole medications for seven to 14 days can successfully clear a yeast infection. Medication is usually vaginal cream, ointment, tablet or suppository.
  • Multidose oral medication. Your doctor might prescribe two or three doses of fluconazole to be taken by mouth instead of vaginal therapy. However, this therapy isn't recommended for pregnant women.
  • Maintenance plan. For recurrent yeast infections, your doctor might recommend a medication routine to prevent yeast overgrowth and future infections. Maintenance therapy starts after a yeast infection is cleared with treatment. You may need a longer treatment of up to 14 days to clear the yeast infection before beginning maintenance therapy. Therapies may include a regimen of oral fluconazole tablets once a week for six months. Some doctors prescribe clotrimazole as a vaginal suppository used once a week instead of an oral medication.

Your sex partner probably won't need to be treated for a yeast infection. If you have recurrent yeast infections, your doctor might recommend treating your partner if your partner has symptoms of a genital yeast infection (balanitis) or using condoms during intercourse.

Although some studies on alternative therapies for yeast infection have been done, well-designed and controlled trials are needed to investigate these therapies before experts can make any recommendations.

Examples include:

  • Boric acid. Boric acid — a vaginal insert (suppository) available by prescription — may be considered to help treat chronic, less common strains of candida and candida that are resistant to azole medications. Treatment is only vaginal and is applied twice daily for two weeks. However, boric acid can irritate your skin and can be fatal if accidentally ingested, especially by children.
  • Yogurt. Some women find relief from yeast infection symptoms when eating yogurt or applying it vaginally, and there is some evidence to support this. Some studies found that yogurt was more effective than placebo or vaginally applied clotrimazole. However, only a small number of women were included.

Before trying any alternative therapy, check with your doctor to weigh the pros and cons in your situation.

To reduce your risk of vaginal yeast infections:

  • Wear cotton underwear and loose-fitting pants or skirts.
  • Avoid tight-fitting underwear or pantyhose.
  • Immediately change out of wet clothes, such as swimsuits or workout attire.
  • Stay out of hot tubs and very hot baths.
  • Avoid unnecessary antibiotic use, such as for colds or other viral infections.
Sept. 18, 2015