What Causes a Yeast Infection: Triggers, Myths & Treatment

Nearly 75% of women will face a vaginal yeast infection in their lifetime — and when it happens, the culprit is almost always the same fungus already living quietly in your body. Candida overgrowth takes hold when common factors like antibiotics, hormonal shifts, or underlying health conditions disrupt the delicate vaginal environment that normally keeps this fungus in check.

Primary cause: Overgrowth of Candida fungus · Most common fungus: Candida albicans · Key risk factor: Changes in vaginal flora · Common triggers: Warm, humid conditions · Affected areas: Vagina, skin

What are the main causes of a yeast infection?

A vaginal yeast infection — medically called vulvovaginal candidiasis (VVC) — happens when Candida fungus overgrows in the vaginal area. Candida normally lives in small amounts in your body, including your mouth, digestive tract, and vagina. Problems arise when something disrupts the delicate balance that keeps this fungus in check.

Candida albicans causes over 90% of vulvovaginal candidiasis cases, according to peer-reviewed research published in PMC. The remaining cases come from non-albicans species like Candida glabrata, which account for roughly 8% of infections and can be harder to treat.

The vagina normally maintains an acidic environment populated by protective bacteria, primarily Lactobacillus. These bacteria produce lactic acid that keeps vaginal pH in a healthy range (3.8–4.5). When this balance shifts — whether through medications, hormonal changes, or health conditions — Candida can multiply rapidly. The World Health Organization notes that “changes in the vagina’s normal acidity, natural microbiome or hormonal balance can create an environment that encourages yeast overgrowth.”

Overgrowth of Candida fungus

Candida overgrowth occurs when the fungus multiplies beyond normal levels. This typically happens because something has weakened the vaginal environment’s defenses. According to Mayo Clinic, the primary causes include antibiotic use, pregnancy, uncontrolled diabetes, weakened immunity, and estrogen-raising therapies.

Role of Candida albicans

Candida albicans is a yeast — not a bacteria — which is why antibacterial antibiotics don’t treat yeast infections and can actually trigger them. The fungus thrives in warm, moist environments and feeds on sugars in the body. Elevated estrogen levels stimulate glycogen deposition in the vaginal epithelium, providing an ideal substrate for C. albicans to grow, according to research from PMC.

What can trigger a yeast infection?

Understanding what disrupts vaginal flora helps explain why certain situations reliably increase infection risk. The CDC lists specific risk factors that create conditions favorable for Candida overgrowth.

Antibiotic use

Antibiotics are one of the most common triggers. These medications don’t selectively target only harmful bacteria — they also kill the protective Lactobacillus bacteria that maintain vaginal acidity. Without this bacterial defense, Candida can grow unchecked. WHO confirms that “antibiotic use disrupts vaginal bacteria balance, allowing Candida overgrowth.”

Hormonal changes

Hormonal fluctuations during pregnancy, your menstrual cycle, or while using hormonal birth control all increase susceptibility. Estrogen promotes glycogen storage in vaginal cells, and Candida feeds on this sugar. The PMC explains that “elevated estrogen levels stimulate glycogen deposition in the vaginal epithelium, providing a perfect substrate for C. albicans development.”

Weak immune system

A weakened immune system reduces your body’s ability to keep Candida in check. Monistat notes that “weakened immune system increases susceptibility to yeast infections.” This includes conditions like HIV, chemotherapy, or chronic illnesses that impair immune function.

• Tight, non-breathable clothing and wet workout gear create warm, humid conditions that Candida loves
• Scented soaps, bubble baths, and feminine hygiene sprays can irritate vaginal tissue
• Douching destroys beneficial bacteria and alters pH balance
• Uncontrolled diabetes provides excess glucose that fuels Candida growth

Is a yeast infection an STI?

This question causes significant confusion and unnecessary worry in relationships. The short answer is no — vaginal yeast infections are not classified as sexually transmitted infections.

Transmission myths

Many people mistakenly believe that a yeast infection is proof of infidelity or poor hygiene. Hey Jane addresses this directly: “Sex can sometimes contribute to yeast infections by altering vaginal pH, but it is not the primary cause.” The fungus that causes yeast infections is already present in your body — it’s an overgrowth of something native, not an foreign invader.

Not sexually transmitted

Yeast infections don’t meet the clinical definition of an STI. Women’s Health of CVA confirms that “yeast infections are not STDs but can be transmitted during sex.” The key distinction: they can be passed between sexual partners, but they aren’t exclusively sexually transmitted and often develop without any sexual contact at all.

What gets mistaken for a yeast infection?

Several conditions share symptoms with yeast infections, which is why self-diagnosis can be unreliable. Getting the right diagnosis matters because treatments differ significantly.

Bacterial vaginosis

Bacterial vaginosis (BV) produces similar symptoms — itching, discharge, and irritation — but stems from an imbalance of different bacteria rather than fungus. BV typically causes a thin, grayish discharge with a fishy odor, especially after sex. It requires antibiotics, not antifungal treatment. Because symptoms overlap substantially, Mayo Clinic recommends professional testing to confirm the diagnosis.

STIs like trichomoniasis

Trichomoniasis, caused by a parasite, also mimics yeast infection symptoms but requires different medication (metronidazole or tinidazole). Both BV and trichomoniasis can coexist with yeast infections, complicating self-diagnosis even further.

The pattern: misdiagnosis wastes time and money while allowing the actual condition to worsen, making professional testing essential when symptoms persist or first appear.

Can a yeast infection go away on its own?

Many people wonder whether they need treatment or if their body will handle the infection naturally. The answer depends on individual factors and infection severity.

Mild cases

Very mild yeast infections may resolve without treatment as your body naturally rebalances vaginal flora. However, this typically takes longer, causes ongoing discomfort, and carries the risk of worsening before improvement.

When treatment needed

According to Harvard Health, up to 45% of women experience two or more yeast infections in their lifetime. Recurrent infections — defined as four or more per year — warrant medical evaluation to identify underlying causes and receive appropriate treatment. If you’re interested in exploring dietary changes, you can learn more about the keto diet at What is the keto diet.

You should see a doctor if: you have never had a yeast infection before (to confirm the diagnosis), symptoms are severe, over-the-counter treatment doesn’t help within a few days, you experience four or more infections per year, or you’re pregnant (certain antifungals are unsafe during pregnancy).

The implication: delaying treatment for recurrent infections can mask serious underlying conditions like diabetes or immune disorders that perpetuate the cycle.

How to treat a yeast infection

Effective treatment options exist for both over-the-counter and prescription contexts. Treatment duration and formulation vary based on infection severity and whether it’s your first occurrence.

• Antifungal creams and suppositories (Monistat, generic equivalents) — typically 1 to 7 days of treatment
• Oral fluconazole (Diflucan) — single dose for uncomplicated cases, prescription required
• Longer prescription courses for recurrent infections (typically 14 days or maintenance therapy)

Separating myths from medical facts

Misinformation about yeast infections abounds, often leading to ineffective treatments, unnecessary worry, or blame unfairly placed on partners or personal habits.

Several myths persist despite lacking scientific support. The idea that inserting garlic treats yeast infections has no evidence and risks complications, according to Monistat. Similarly, the belief that diet or gluten causes yeast infections lacks strong evidence — vaginal Candida isn’t related to the yeast used in bread, as Athens ObGyn notes.

“Changes in the vagina’s normal acidity, natural microbiome or hormonal balance can create an environment that encourages yeast overgrowth.”

— World Health Organization (Global Health Authority)

“In the United States, VVC… affects 70–75% of women during their lifetime and results in an estimated 1.4 million outpatient visits each year.”

— Oxford Academic Review (Clinical Infectious Diseases)

The implication: most women will encounter this condition at some point, and its causes are primarily biological rather than behavioral. Blame and shame are misplaced — the real factors are things like antibiotic prescriptions you didn’t ask for, pregnancy, diabetes management, or simply your body’s natural chemistry.

Related reading: Hand, Foot and Mouth Disease Treatments · What Is Paprika Made Of? Myths & Facts

Triggers like antibiotics, hormones and weakened immunity driving yeast overgrowth closely mirror key vaginal thrush triggers, underscoring common vulnerabilities in vaginal health.

Frequently asked questions

For women who’ve experienced recurrent infections, understanding that these are often driven by host factors — not behavior — can reduce anxiety and encourage appropriate medical evaluation rather than repeated self-treatment with over-the-counter products.