Vaginal infections and vaginitis, or inflammation of the vagina, are very common — so much so that most women will experience one or the other, and likely both, during their lifetime.

Symptoms of either a vaginal infection or vaginitis may include vaginal discharge, itching, burning, pain, and a strong odor.

While some vaginal infections are caused by sexually transmitted infections, other very common ones are not.

Some women seem to be more prone to vaginal infections than others for reasons that are not entirely obvious, says Gregory R. Moore, MD, MPH, an obstetrician-gynecologist at Stamps Health Services at the Georgia Institute of Technology in Atlanta.

Why Do Vaginal Infections Happen?

The vagina contains an ecosystem of microorganisms known as the vaginal microbiome. A healthy vaginal microbiome is made up of hundreds of types of bacteria and yeast that keep the vagina healthy.

But certain things can change the environment in the vagina, enabling bacterial or yeast overgrowth and causing symptoms:

• Douching, or rinsing the vagina with water or other liquid

• Female hormone level changes

• Taking antibiotics

• Vaginal intercourse

• Pregnancy and breastfeeding

Note that douching is unnecessary and potentially harmful.

The Most Common Types of Vaginal Infections

There are three common types of vaginal infections, says Cynthia Krause, MD, an assistant clinical professor of obstetrics, gynecology, and reproductive science at the Ichan School of Medicine at Mount Sinai in New York City: yeast infections, bacterial vaginosis, and trichomoniasis, a sexually transmitted infection.

Yeast Infection

The most common type of vaginal infection, a yeast infection is caused by one of the many types of fungus known as candida. According to Dr. Krause, “There are many species of yeast, or candida. Candida albicans is the most common.”

Normally, candida lives harmlessly in your body in small numbers, including in the vagina. But under certain conditions, an overgrowth of candida can occur, causing a vaginal infection.

Those conditions might include hormone level changes due to pregnancy, birth control pills, menstruation, or menopause. Some other conditions that raise the risk of vaginal yeast infections include having frequent or chronic high blood sugar and a weakened immune system because of a medical condition like HIV or AIDS, says the Centers for Disease Control and Prevention.

Symptoms of a vaginal yeast infection include a thick, white discharge that some women describe as resembling cottage cheese. Yeast infections can also cause vaginal itching and redness of the vulva (the lips of the external female genital area) and vagina.

Treatments for a yeast infection are available over the counter or by a prescription and include antifungal medications, which are available as creams, ointments, tablets, or suppositories.

Bacterial Vaginosis

Along with yeast, friendly bacteria called lactobacilli live in the vagina. When the number of lactobacilli gets too low, it can trigger a condition called bacterial vaginosis.

Why bacteria levels change is not known, but the normal lactobacilli can be replaced by other, infection-causing bacteria.

“Gardnerella is the bacteria most often associated with bacterial vaginosis,” Krause says. “It is the lack of lactobacilli and overgrowth with these other bacteria that cause the symptoms of infection.”

With bacterial vaginosis, a woman may see a thick or whitish discharge, or one that is slippery and clear. It is not likely to itch or burn. A fishy odor may be noticeable, especially during intercourse.

Antibiotics like metronidazole and clindamycin are often prescribed to treat bacterial vaginosis.

These medications can be taken orally, and they also come as creams or gels to be inserted into the vagina. Generally, one round of antibiotics taken for a week will clear up the infection, but some people may need an additional round.

Trichomoniasis

“Of the three most common vaginal infections, trichomonas vaginitis, also called trichomoniasis, is the only one that is a true sexually transmitted infection,” Krause says.

Commonly called trich, it is caused by a single-celled parasite, Trichomonas vaginalis, and is passed from partner to partner during intercourse.

The symptoms of trichomoniasis are similar to other vaginal infections: burning, irritation, redness, and swelling of the vulva, with a yellow-gray or greenish vaginal discharge, possibly with a fishy odor. Some women also experience pain during urination.

Treatment for trichomoniasis involves oral antibiotics that are effective against parasitic infections. These medications may be taken in one large dose, called a megadose, or in multiple doses.

You may start to feel better after a few days, but it's important to finish your medication as prescribed by your doctor even if your symptoms go away. 

Other Conditions That Affect the Vagina

There are other common vaginal infections and causes of vaginal itching.

Chlamydia

Chlamydia is a sexually transmitted disease that can cause inflammation of the vagina. Some women will have discharge with chlamydia, and some will not. If the infection spreads beyond the vagina and cervix, women may experience bleeding between periods or after vaginal intercourse. But it’s important to note that such bleeding can be caused by other factors as well.

“Sexually active women up to age 26 should be tested annually for chlamydia because it so often comes without symptoms and can linger and do a fair amount of damage to fertility,” Dr. Moore says.

To treat chlamydia, your doctor will prescribe a course of antibiotics.

Gonorrhea

Gonorrhea is another, highly contagious sexually transmitted infection that often doesn’t cause any symptoms but can cause vaginal discharge, pain during urination, and pain during vaginal sex.

Women who have gonorrhea often also have chlamydia, so a woman who tests positive for one of these bacterial infections will likely be treated for the other.

Noninfectious Vaginitis

Noninfectious vaginitis occurs when the vagina becomes sensitive to an irritant. This is not an infection, so the first line of defense is to remove whatever you are having a reaction to, Moore says.

While it’s not always easy to pinpoint the cause, common offenders include scented tampons, perfumed soaps, fabric softeners, or other products with dyes or fragrances, such as vaginal sprays and douches.

In some cases, removing the cause may not be enough, and additional treatment, such as steroids, might be the next step.

Another form of noninfectious vaginitis is called atrophic vaginitis, and it typically occurs when female hormone levels decrease around the time of menopause, and the vaginal walls become thinner, drier, and less flexible.

Vulvodynia: Persistent Pain of the Vulva

Vulvodynia is chronic pain or discomfort of the vulva without a known cause. The symptoms are similar to vaginal infections: burning, stinging, rawness, soreness, and swelling. Symptoms may be constant or occasional. Since no single treatment works for everyone, you may need to talk to your doctor about what might work best for you.

Viral Vaginitis

Viruses also can cause vaginal infections. Most viruses that directly affect the vagina are spread through sexual contact.

“The herpes simplex virus is a common cause of viral vaginosis,” Moore says. Symptoms include pain in the genital area from lesions or sores. The sores on the vulva or vagina are usually visible, but if the infection is within the vagina or on the cervix, a pelvic exam by your gynecologist is the best way to confirm the diagnosis.

The Takeaway 

Vaginal infections are extremely common, and nearly every woman will experience one at some point in her life. A number of factors can cause a vaginal infection, so if you’re experiencing symptoms like itching, burning, and a strong odor, it’s best to check with your gynecologist to find the cause and get the appropriate treatment.

Additional reporting by Ashley Welch.