Vaginal infection, also called vaginitis, affects millions of women every year and can cause uncomfortable symptoms like itching, discharge, and irritation. Understanding the different types of infections and how to recognize them can help you seek the right care and get relief faster.
What Is a Vaginal Infection?
A vaginal infection happens when the normal balance of bacteria, yeast, and other microorganisms in the vagina gets disrupted. The vagina naturally hosts many different types of bacteria and small amounts of yeast, which usually exist in harmony without causing any problems. When something upsets this delicate balance, one type of organism can grow too much, leading to infection and inflammation.[1]
Vaginitis is the medical term for inflammation or infection of the vagina. When the inflammation also affects the vulva—the external part of the genitals including the labia and clitoris—the condition is called vulvovaginitis. These infections can make the vaginal area swollen, itchy, sore, or cause unusual discharge and odor.[1]
Vaginal infections are extremely common. An estimated 75% of women will experience at least one episode during their lives, and between 40% and 45% will have two or more episodes. These infections are most frequent during the reproductive years, from puberty through menopause.[3][4]
Epidemiology
Vaginal infections represent one of the most common reasons women visit their doctors, accounting for millions of medical appointments each year.[6] Among women who haven’t yet gone through menopause, yeast infections and bacterial vaginosis are the two most common types of vaginal infection.[1]
When healthcare providers can identify a specific cause for vaginitis, bacterial vaginosis accounts for 40% to 50% of cases. Vulvovaginal candidiasis, commonly known as a yeast infection, accounts for 20% to 25% of cases. Trichomoniasis, an infection caused by a parasite, represents 15% to 20% of cases. Noninfectious causes, including irritation from chemicals, hormonal changes, and inflammation, account for the remaining 5% to 10% of vaginitis cases.[3][14]
The condition affects women across all age groups, though the types of infections vary by life stage. During pregnancy, hormonal changes can increase the risk of developing vaginal infections, particularly yeast infections and bacterial vaginosis. After menopause, lower estrogen levels can lead to a different type of vaginal inflammation called atrophic vaginitis, which makes vaginal tissues thinner, drier, and more easily irritated.[1][3]
Causes
Vaginal infections have many different causes, ranging from infectious organisms to chemical irritation and hormonal changes. Understanding the root cause helps determine the right treatment approach.[1]
Bacterial vaginosis results from an overgrowth of bacteria that are normally present in the vagina. A healthy vagina maintains a careful balance of many different kinds of bacteria, yeast, and other microorganisms. When this balance gets upset, one type of bacteria—usually Gardnerella vaginalis—grows too much. This overgrowth leads to bacterial vaginosis. It’s important to note that bacterial vaginosis is not caused by a single bacteria invading from outside, but rather by an imbalance of organisms already living in the vagina.[1][3]
Yeast infections are caused by an overgrowth of a fungus called Candida, most commonly Candida albicans. Small amounts of this fungus naturally live in the mouth, digestive system, and vagina. This is perfectly normal and healthy. Problems arise only when the fungus multiplies out of control. When Candida penetrates the mucosal lining of the vagina, it triggers an inflammatory response that leads to the symptoms of a yeast infection.[4][9]
Trichomoniasis is caused by a parasite called Trichomonas vaginalis and spreads through sexual contact. Unlike bacterial vaginosis and yeast infections, which result from imbalances of organisms already present in the body, trichomoniasis comes from an external source and is considered a sexually transmitted infection.[1][3]
Viral infections can also cause vaginal inflammation. The herpes simplex virus and human papillomavirus, both spread through sexual contact, can cause painful sores or warts on the vagina and vulva.[1]
Noninfectious vaginitis develops when something irritates the vaginal tissues without involving an infection. This type often results from chemicals in soaps, douches, feminine hygiene sprays, laundry detergents, and fabric softeners. Some women may have allergic reactions to these products, or their vaginal tissues may simply be sensitive to certain chemicals.[1][3]
Vaginal atrophy occurs when estrogen levels drop, usually after menopause or surgical removal of the ovaries. These hormonal changes cause the vaginal walls to become thin, dry, and easily irritated, leading to inflammation and discomfort.[1]
Risk Factors
Certain factors can increase your likelihood of developing a vaginal infection. Some of these risk factors involve medical conditions, while others relate to medications, personal habits, or life circumstances.[1]
Antibiotic use is one of the most common risk factors for yeast infections. When you take antibiotics to treat an infection elsewhere in your body, these medications don’t just kill the harmful bacteria causing your illness—they also eliminate the good bacteria in your vagina. Without these protective bacteria to keep yeast growth in check, Candida can multiply rapidly and cause a yeast infection.[4][5]
Pregnancy and hormonal changes significantly affect vaginal health. During pregnancy, hormonal shifts can disrupt the normal balance of yeast and bacteria in the vagina. The increased levels of estrogen during pregnancy create conditions that favor Candida growth. Similarly, using birth control pills or experiencing normal changes during the menstrual cycle can alter hormone levels and increase infection risk.[4][5]
Diabetes, especially when not well-controlled, increases the risk of yeast infections. High blood sugar levels mean there’s extra sugar in the urine, which provides food for yeast to grow and multiply. Unmanaged diabetes can also weaken the immune system, making it harder for the body to fight off infections.[4][5]
Weakened immune system from conditions like HIV infection or medications that suppress immunity, such as corticosteroids, can make you more susceptible to vaginal infections. When your immune system isn’t functioning at full strength, it’s less able to control the growth of organisms in the vagina.[4]
Sexual activity plays a role in some types of vaginal infections. While yeast infections are not considered sexually transmitted infections, there’s an increased risk when you first become sexually active. Oral sex has also been linked to yeast infections. The introduction of new bacteria during sexual activity can disrupt the vaginal environment. Trichomoniasis, chlamydia, and gonorrhea spread directly through sexual contact with an infected partner.[1][5]
Personal hygiene habits can either protect against or contribute to vaginal infections. Staying in wet bathing suits or sweaty exercise clothes creates a warm, moist environment where yeast and bacteria thrive. Wearing tight, non-breathable clothing has the same effect. Using scented tampons, sprays, soaps, or deodorants on the genital area can irritate delicate vaginal tissues and upset the natural bacterial balance. Douching, once thought to promote cleanliness, actually destroys the friendly bacteria that help maintain a healthy vaginal environment.[4][6]
Reduced acidity in the vagina can make infection more likely. The vaginal pH is normally acidic, which helps protective lactobacilli bacteria thrive. Menopause, exposure to semen, use of vaginal products, or infection itself can change the vaginal pH. When acidity decreases, the number of protective bacteria drops while harmful bacteria increase, sometimes leading to bacterial vaginosis.[6]
Exposure to bacteria from the digestive system can lead to vaginal infection. If fecal matter from the anus comes into contact with the vagina, bacteria can enter and shift the bacterial balance or cause an infection. This is why healthcare providers recommend wiping from front to back after using the bathroom.[6]
Symptoms
Vaginal infections can produce a range of uncomfortable symptoms, though some women may have no symptoms at all. The specific symptoms often depend on the type of infection, but many overlap between different types, making it difficult to identify the cause based on symptoms alone.[3]
Changes in vaginal discharge are among the most common signs of infection. The color, amount, texture, and odor of discharge can provide clues about the type of infection. Bacterial vaginosis typically causes a thin, grayish-white discharge with a strong, unpleasant odor often described as fishy. This odor may become more noticeable after sexual intercourse. Yeast infections usually produce a thick, white discharge that resembles cottage cheese in texture. Trichomoniasis causes a greenish-yellow, sometimes frothy discharge.[3][8]
Itching and irritation affect many women with vaginal infections. Yeast infections are particularly known for causing intense itching in and around the vagina and vulva. This itching can be persistent and bothersome, significantly affecting quality of life. Women may also experience a general feeling of irritation and discomfort in the vaginal area.[3][4]
Redness and swelling commonly occur with vaginal infections. The vulva and vagina may appear red and inflamed. With yeast infections, you might notice swelling of the labia. The skin of the vulva can develop small cuts or tiny cracks, which can be painful and make the area more vulnerable to other infections.[4]
Burning sensations can happen in different situations. Many women experience burning during urination, which occurs when urine contacts inflamed vaginal tissues. Burning or soreness may also be present even when not urinating, simply as a result of the inflammation itself.[3][4]
Pain during sexual activity is another common symptom. The inflammation and irritation caused by infection can make sexual intercourse uncomfortable or painful. This symptom, called dyspareunia, affects many women with vaginal infections.[3]
Vaginal odor varies by infection type. While bacterial vaginosis produces a distinctive fishy smell, yeast infections typically don’t cause a strong odor. The intensity of odor can fluctuate throughout the menstrual cycle.[7]
Some women may notice light vaginal bleeding or spotting, though this is less common than other symptoms. It’s important to understand that symptoms alone cannot reliably distinguish between different causes of vaginitis. The symptoms of bacterial vaginosis, yeast infections, and trichomoniasis overlap considerably, and you could even have more than one infection at the same time.[1][3]
Prevention
While not all vaginal infections can be prevented, several lifestyle practices and habits can reduce your risk and help maintain a healthy vaginal environment.[6]
Good genital hygiene forms the foundation of prevention. Keep your vaginal area clean using mild, unscented soap and water. The vagina is self-cleaning, so you don’t need to wash inside it or use harsh cleansers. In fact, doing so can disrupt the natural balance of bacteria. After using the bathroom, always wipe from front to back to prevent bacteria from the anus from spreading to the vagina and urinary tract. This simple habit helps prevent many infections.[7][22]
Clothing choices matter more than you might think. Choose underwear made from cotton or other breathable fabrics that allow air circulation and help keep the genital area dry. Avoid wearing tight pants or clothing that doesn’t breathe, as these trap heat and moisture against your skin, creating an ideal environment for yeast and bacteria to multiply. Some women find that sleeping without underwear helps keep the area dry and prevents infections. Change out of wet bathing suits and damp exercise clothes as soon as possible after swimming or working out.[4][22]
Avoid potential irritants that can disrupt your vaginal health. Don’t use douches, feminine hygiene sprays, scented powders, or perfumed tampons. These products contain chemicals that can irritate vaginal tissues and destroy the beneficial bacteria that protect against infection. Despite marketing messages suggesting these products promote cleanliness, they actually do more harm than good. Similarly, be mindful of laundry detergents and fabric softeners, as chemicals in these products can sometimes cause irritation when they come into contact with your underwear.[1][22]
Dietary considerations may help prevent yeast infections. Yeast thrives on sugar, so reducing your intake of foods and drinks high in simple sugars—like soda, candy, and pastries—may help curb yeast growth. Some women find that eating yogurt with live bacterial cultures or taking probiotic supplements helps maintain a healthy vaginal environment. Probiotics contain beneficial bacteria, particularly Lactobacillus acidophilus, which are important for vaginal health. While research doesn’t consistently prove that probiotics prevent yeast infections, they’re generally safe and may offer some benefit.[18]
Managing underlying health conditions helps prevent recurrent infections. If you have diabetes, keeping your blood sugar levels well-controlled reduces your risk of yeast infections. Talk with your doctor about the best ways to manage your diabetes. If you need to take antibiotics for an infection, consider taking probiotics at the same time to help maintain your vaginal bacterial balance. Let your doctor know if you get frequent yeast infections when taking antibiotics—they may be able to prescribe preventive antifungal medication.[4][18]
Sexual health practices can reduce infection risk. While yeast infections aren’t sexually transmitted, they can sometimes be passed between partners. Communicate with your partner if you have an infection, and avoid sexual activity until treatment is complete. Using condoms may help prevent transmission of trichomoniasis and other sexually transmitted infections that can cause vaginal symptoms.[1]
Regular healthcare visits support vaginal health. Annual examinations allow your healthcare provider to check for any problems before symptoms develop. If you experience recurring infections, your doctor can help identify underlying causes and develop a prevention plan tailored to your situation.[7]
Pathophysiology
Understanding how vaginal infections develop requires knowledge of the vagina’s normal physiology and what changes when infection occurs.[3]
The healthy vagina maintains a complex ecosystem of microorganisms living in careful balance. This ecosystem includes many species of bacteria, with lactobacilli being the most important protective bacteria. These beneficial bacteria produce lactic acid, which keeps the vaginal environment acidic, typically with a pH below 4.5. This acidic environment helps prevent the overgrowth of potentially harmful bacteria and yeast. The lactobacilli also produce hydrogen peroxide and other substances that further protect against infection.[6][14]
In bacterial vaginosis, the normal balance shifts dramatically. The number of protective lactobacilli decreases, causing the vaginal pH to rise (become less acidic). When acidity decreases, other bacteria that prefer a less acidic environment begin to multiply. These include anaerobic bacteria—bacteria that don’t need oxygen to grow—such as Gardnerella vaginalis, Mobiluncus species, and others. Bacterial vaginosis represents a polymicrobial condition, meaning multiple species of bacteria are involved rather than just one. The overgrowth of these bacteria produces chemicals called amines, which cause the characteristic fishy odor. The bacteria also trigger an inflammatory response in the vaginal tissues, though bacterial vaginosis typically causes less inflammation than other types of vaginitis.[3][14]
Yeast infections develop through a different mechanism. Small amounts of Candida fungus normally live in the vagina without causing problems. When conditions favor yeast growth—such as after antibiotic use, during pregnancy, or with high blood sugar—the yeast multiplies rapidly. Candida exists in two forms: a harmless yeast form that floats freely, and a more invasive hyphal form that can penetrate tissues. When Candida switches to the hyphal form and penetrates the mucosal lining of the vagina, it triggers a strong inflammatory response. The immune system releases inflammatory chemicals called cytokines, which cause the redness, swelling, and itching characteristic of yeast infections. Unlike bacterial vaginosis, yeast infections don’t significantly change vaginal pH.[4][9]
In trichomoniasis, the parasite Trichomonas vaginalis attaches to vaginal cells and damages them. The parasite has whip-like structures called flagella that it uses to move and attach to tissues. It produces enzymes that break down proteins in vaginal cells, causing cell death and inflammation. The damage to cells and the inflammatory response produce the symptoms of infection. Trichomoniasis raises the vaginal pH, making the environment less acidic. The parasite can also damage the protective barrier of the vaginal lining, making it easier for other infections to take hold.[3]
Atrophic vaginitis results from hormonal rather than infectious changes. Estrogen normally helps maintain thick, moist vaginal tissues with good blood flow. When estrogen levels drop after menopause, the vaginal tissues become thinner, less elastic, and produce less moisture. The number of lactobacilli decreases, causing the pH to rise. These changes make the vagina more susceptible to irritation and infection. The tissues become fragile and may develop small tears, leading to bleeding and discomfort.[3]
Noninfectious vaginitis involves inflammation without infection. Chemical irritants in soaps, detergents, or hygiene products can trigger an allergic or inflammatory response in vaginal tissues. This causes the release of inflammatory chemicals that lead to swelling, redness, itching, and discomfort, even though no infectious organism is present. Repeated exposure to irritants can damage the protective barrier of vaginal tissues, potentially making them more vulnerable to actual infections.[3][6]
Understanding these mechanisms helps explain why different infections require different treatments and why maintaining the vagina’s natural balance is so important for prevention. The complexity of the vaginal ecosystem also explains why disruptions—from antibiotics, hormonal changes, or other factors—can so easily lead to infection.[1]
