Yeast infections are caused by an overgrowth of Candida yeast, usually Candida albicans, that normally lives quietly in the vagina. The common triggers are anything that disrupts the balance keeping it in check: antibiotics, higher estrogen (pregnancy, hormonal birth control), uncontrolled diabetes, a weakened immune system, and a warm, moist environment. It is not usually a sexually transmitted infection.
with the right treatment
testing, not symptoms, decides
| Item | Value |
|---|---|
| Curable? | yes — with the right treatment |
| Tested by | exam + lab |
| If you may have it | get tested — testing, not symptoms, decides |
What a yeast infection actually is
A vaginal yeast infection — clinicians call it vulvovaginal candidiasis — is a fungal infection CDC. Small amounts of Candida live on the skin and in the vagina, mouth, and gut without causing trouble. The vagina also hosts protective bacteria (lactobacilli) that keep the environment slightly acidic, which holds the yeast back. A yeast infection happens when that balance tips and the yeast multiplies faster than the local defenses can manage.
It is one of the most common fungal infections, and most cases come from the species Candida albicans. Because it grows from yeast that's already present, you don't have to catch it from anyone, so it isn't classed as an STI.
What triggers the overgrowth
Most triggers work by either knocking out the protective bacteria or feeding the yeast. The big ones:
- Antibiotics. A course of antibiotics kills off the protective lactobacilli along with the bacteria you're treating, leaving room for yeast to take over. This is one of the most common reasons a yeast infection appears out of nowhere.
- Estrogen and hormonal changes. Pregnancy and higher-estrogen states raise the risk because estrogen increases the sugar (glycogen) available in the vaginal lining, which yeast feed on. Hormonal contraception can have a similar effect in some people.
- Uncontrolled diabetes. Higher blood sugar means more sugar in vaginal secretions, giving yeast fuel. Poorly controlled diabetes is linked to more frequent and more stubborn infections.
- A weakened immune system. Conditions or medications that suppress immunity — including corticosteroids and chemotherapy — let yeast grow unchecked.
- Heat and moisture. Yeast thrives in warm, damp conditions. Tight, non-breathable clothing, staying in a wet swimsuit or sweaty workout gear, and a generally moist environment all encourage overgrowth.
Symptoms — and the silent reality
The classic picture is intense vaginal itching or soreness with abnormal discharge that's often thick and white CDC. People also report pain during sex and discomfort or burning when urinating, as the inflamed tissue reacts to contact.
Most infections are mild. In more severe cases the vulva and vaginal opening become visibly red and swollen, and the skin can develop small cracks or fissures that sting. The discharge is frequently described as looking like cottage cheese — thick, white, and clumpy. It does not have a fishy or foul odor, and that odorless quality helps separate yeast from bacterial vaginosis.
Not every itch is yeast, and not every yeast infection looks identical. Symptoms overlap heavily with other vaginal conditions, so guessing leads people astray.
Is it contagious? How it spreads
A yeast infection is not usually acquired through sex, so it isn't treated as a sexually transmitted infection. It grows from yeast already living in the body when conditions shift in its favor. Sexual activity can sometimes irritate already-inflamed tissue or, occasionally, pass yeast between partners, but it isn't the typical route.
Men can develop a related yeast infection — usually irritation, redness, or a rash on the penis — particularly after sex with a partner who has one or with their own risk factors. If you're wondering about that side of it, see can men get yeast infections? symptoms & treatment for the specifics can men get yeast infections? symptoms & treatment.
How it's diagnosed
Diagnosis is straightforward. A clinician examines a sample of vaginal discharge under the microscope — a wet prep mixed with saline or 10% potassium hydroxide (KOH) — looking for budding yeast and the branching forms called hyphae or pseudohyphae CDC, 2021. A fungal culture may be added, especially for stubborn or recurrent cases. The vaginal pH stays normal, under 4.5, which helps rule out other causes.
Testing matters because the symptoms mimic other infections, and the treatments are completely different. Here's how a clinician tells the three most common vaginal conditions apart:
| Condition | Discharge | Odor | Vaginal pH | STI? |
|---|---|---|---|---|
| Yeast infection (Candida) | Thick, white, 'cottage cheese' | None | Normal (under 4.5) | No |
| Bacterial vaginosis | Thin, milk-like | Fishy (positive whiff test) | Above 4.5 | No |
| Trichomoniasis | Diffuse, yellow-green | Malodorous | Above 4.5 | Yes (Trichomonas vaginalis) |
Testing is usually a quick exam or a self-collected or clinician-collected swab, sometimes with a urine cup if other infections are also being checked, and results typically come back within a few days. It's free or low-cost at health departments, Planned Parenthood, and Title X clinics. If your symptoms followed a possible exposure to an STI and you're not sure whether this is yeast or something sexually transmitted, read when to test after exposure and go get tested rather than self-treating in the dark when to test after exposure get tested.
Treatment
Uncomplicated yeast infections respond well to antifungal medication. The standard options are an intravaginal azole cream — for example clotrimazole 1% applied for several days to two weeks, or miconazole 2% for a week, many of which are available over the counter — or a single oral dose of fluconazole 150 mg. Recurrent or complicated infections need a longer initial course followed by maintenance therapy, such as weekly oral fluconazole over several months.
It's a defined course, so finish all of it even once the itching eases. Stopping early invites a quick relapse. If symptoms don't improve or keep returning, go back rather than buying another over-the-counter box, because a non-yeast condition or a resistant species may be the real culprit. For the full breakdown of options and what to expect, see yeast infection treatment.
What happens if it's left untreated
A single yeast infection is generally mild and not dangerous, but ignoring symptoms has costs. The discomfort, itching, and pain during sex tend to persist or worsen, and severe inflammation can crack the vaginal skin, which is raw and easily irritated.
The bigger issue is recurrence. A recurrent yeast infection is defined as three or more symptomatic episodes in under a year, a pattern that affects under 5% of women RVVC review. When episodes hit four or more times a year, clinicians treat it differently — an induction course followed by months of weekly fluconazole controls symptoms in most people, but recurrences are common once maintenance stops. Stubborn cases sometimes turn out to involve a non-albicans Candida species that resists standard fluconazole, so culture matters when treatment keeps failing.
How to lower your risk
Since the triggers are about balance and moisture, prevention targets both CDC:
- Wear cotton underwear and breathable, not-too-tight clothing so the area stays dry rather than warm and damp.
- Keep the genital area clean and dry; change out of wet swimsuits or sweaty workout clothes promptly.
- Skip douches and scented vaginal products, which disrupt the protective bacteria.
- If you're prone to infections after antibiotics, ask your clinician whether a preventive antifungal makes sense for you.
- Manage blood sugar if you have diabetes, since high glucose feeds the yeast.
Condoms used every time mainly lower risk for the sexually transmitted infections that mimic yeast, and routine testing catches infections that produce no symptoms. For a fuller checklist, see how to prevent yeast infections.
When to see a clinician
See a clinician if this is your first suspected yeast infection, if over-the-counter treatment doesn't clear things up, if symptoms keep coming back, if you're pregnant, or if you have diabetes or a weakened immune system. Also get checked if there's a fishy odor, yellow-green discharge, or any chance of an STI exposure, since those point away from yeast. Clinics handle this daily and it says nothing about you as a person. If you're choosing where to go, you can compare testing providers first compare testing providers.