Vaginal yeast infections are caused by an overgrowth of a fungus, usually Candida albicans, which can live naturally in the vagina without causing illness.
The infection, medically known as vulvovaginal candidiasis, can cause itching, irritation, soreness and changes in vaginal discharge. Although common, it can be mistaken for other conditions that require different treatment.
The US Centers for Disease Control and Prevention (CDC) estimates that about 75 percent of women will experience at least one vaginal yeast infection during their lifetime, while 40 to 45 percent will have two or more episodes.
What causes a vaginal yeast infection?
The vagina normally contains a mixture of microorganisms, including bacteria and yeast. Protective bacteria help maintain this environment, but changes can allow Candida to multiply and cause symptoms.
Several factors can increase the risk of an infection, although many cases occur without an identifiable trigger.
They include:
- Antibiotic use: Some antibiotics reduce protective vaginal bacteria, allowing yeast to grow.
- Pregnancy and hormonal changes: Higher oestrogen levels during pregnancy, as well as some hormonal contraceptives and hormone treatments, can increase susceptibility.
- Uncontrolled diabetes: High blood sugar levels can make yeast infections more likely.
- A weakened immune system: Certain medical conditions and medicines that suppress immunity can increase the risk.
- Repeated infections: Some women experience recurrent infections, occasionally involving Candida species that are more difficult to treat.
A vaginal yeast infection is not generally considered a sexually transmitted infection. However, sexual activity can sometimes be associated with its occurrence.
Not having sex frequently enough does not cause a yeast infection, and there is no established evidence that being married increases the risk. Eating too few probiotic foods is also not recognised as a standard cause.
What are the symptoms?
Symptoms can range from mild irritation to more severe inflammation. Common signs include:
- Itching around the vagina and vulva, the external genital area.
- Burning or soreness.
- Redness and swelling.
- Pain during sexual intercourse.
- Discomfort when urinating.
- Thick, white vaginal discharge that may resemble cottage cheese and usually has little or no smell.
Some people carry Candida in the vagina without experiencing symptoms. Finding yeast in a test does not automatically mean treatment is necessary if there are no signs of infection.
Fever, chills and pelvic pain are not typical symptoms of an uncomplicated vaginal yeast infection. Anyone experiencing these symptoms alongside vaginal discomfort should seek medical assessment.
How is a yeast infection different from bacterial vaginosis?
Vaginal yeast infections and bacterial vaginosis (BV) can cause similar symptoms, but they have different causes and require different treatments.
A yeast infection results from an overgrowth of fungus, usually Candida. BV develops when the balance of bacteria in the vagina changes, allowing certain bacteria to become more dominant.
Yeast infections commonly cause itching, irritation and thick, white discharge. BV more often produces thin, greyish-white discharge and a noticeable fish-like odour, although symptoms vary and some people have no symptoms.
Neither condition can be reliably diagnosed from discharge alone. Other vaginal infections, including sexually transmitted infections, can produce overlapping symptoms.
Clostridioides difficile, commonly called C. diff, is a different bacterium that can cause intestinal infection, often following antibiotic use. It is not another form of BV and is not treated as a vaginal yeast infection.
How are vaginal yeast infections diagnosed?
A healthcare professional may ask about symptoms, previous infections and medicines before examining the affected area.
A sample of vaginal discharge may be examined under a microscope or sent for laboratory testing to identify yeast. Testing can be particularly useful when symptoms are unclear, treatment has failed or infections keep returning.
This distinction matters because itching, burning and abnormal discharge are not exclusive to yeast infections. Treating the wrong condition can delay appropriate care.
How are yeast infections treated?
Vaginal yeast infections are treated with antifungal medicines. Depending on the infection and the person’s circumstances, treatment may involve a vaginal cream, a suppository or an oral medicine.
For uncomplicated infections, short courses of vaginal antifungal treatment are often effective. More severe or recurrent infections may require longer treatment and further testing.
Antibiotics are not used to treat a yeast infection because they target bacteria rather than fungi. BV, by contrast, is generally treated with specific antibiotics.
People who are pregnant should consult a healthcare professional before treatment. CDC guidance recommends topical azole antifungal treatment for seven days during pregnancy and advises against oral fluconazole for vaginal yeast infections in this situation.
Anyone whose symptoms persist after treatment, return within a short period or occur repeatedly should seek medical advice rather than repeatedly using antifungal medicines without confirming the cause.
Can vaginal yeast infections be prevented?
Not all infections can be prevented, but some measures may help reduce irritation and risk.
- Avoid vaginal douching, which can disrupt the normal vaginal environment.
- Avoid scented soaps, sprays and other products that irritate the genital area.
- Wear breathable underwear and change out of wet clothing when practical.
- Use antibiotics and other prescribed medicines only as directed.
- Seek appropriate care for diabetes or other conditions that may increase the risk of recurrent infections.
A balanced diet supports general health, but no specific food or probiotic product has been established as a reliable way to prevent or cure vaginal yeast infections.
When should you seek medical advice?
Medical assessment is advisable if symptoms occur for the first time, the cause is uncertain, treatment does not work or infections repeatedly return.
Prompt assessment is particularly important when vaginal symptoms occur with fever, chills, pelvic pain, unusual bleeding or a strong, unpleasant discharge, as these may indicate another condition.
With an accurate diagnosis and appropriate antifungal treatment, most uncomplicated vaginal yeast infections can be treated successfully. Recurrent or complicated cases may need additional investigation to identify the cause and determine the most suitable treatment.
