What Causes Yeast Infections? (And Why They Keep Coming Back)

Medically Reviewed by: Meghan Blake, MD

Yeast infections are one of those health concerns that live in the uncomfortable intersection of "extremely common" and "somehow still embarrassing to discuss." They're accompanied by confusion, misconceptions, and an alarming number of home remedies that can actually make everything worse (looking at you, yogurt tampons).

While yeast infections predominantly affect people with vaginas, they can affect anyone.¹ The fungus responsible—Candida—doesn't discriminate based on anatomy or hygiene practices. What it does care about is environmental conditions: warmth, moisture, and a disrupted microbial ecosystem that allows it to flourish unchecked.

Understanding the root causes of yeast infections is the foundation for both prevention and treatment. So let's talk about why some of us are walking fungal breeding grounds while others seemingly never deal with this particular brand of misery.

What Is a Yeast Infection, Exactly?

A yeast infection, medically known as candidiasis, is caused by yeast or fungus belonging to the Candida species. These infections can occur in different parts of the body—your mouth, your skin folds, under your breasts, and yes, your vagina.²

The most common form is vaginal yeast infection, technically called vulvovaginal candidiasis, which affects about 75% of people with vaginas at some point in their lives.³ That's not a small subset of unlucky individuals—that's three out of every four women you know, including the ones who look like they have their lives together.

The Classic Symptoms

Symptoms often include itching that makes you want to claw your own skin off, burning sensations, pain during sex that makes intimacy feel like punishment, and a thick, white vaginal discharge that resembles cottage cheese (an unfortunate comparison that will ruin cottage cheese for you forever).⁴

Other Types of Yeast Infections You Should Know About

While we're focusing on vaginal yeast infections here, Candida is an equal-opportunity colonizer:

Oral thrush (oral candidiasis) develops in the mouth and is common in babies, elderly individuals, and those with weakened immune systems. It presents as white patches on the tongue and inner cheeks.⁵

Cutaneous candidiasis affects the skin in areas prone to moisture and warmth—armpits, groin, under breasts—leading to itchy, angry rashes that make you hate summer.⁶

Signs of Vaginal Yeast Infections

The typical signs include:⁴

• Itching and irritation in the vagina that ranges from "mildly annoying" to "considering amputation"
• Redness and swelling of the vulva and vagina
• Fragile vulva skin that feels tender and raw
• Burning sensation when urinating (which can be confused with UTI symptoms)
• Thick, white discharge with the consistency of cottage cheese
• Pain during sexual intercourse that makes you question why anyone enjoys sex at all

If you're experiencing these symptoms, resist the urge to self-diagnose and self-treat. Yeast infections, bacterial vaginosis, and UTIs can present with overlapping symptoms—getting an accurate diagnosis matters.

What Actually Causes Yeast Infections?

Here's the thing: Candida is naturally found on our skin, in our mouths, and in our digestive tracts. This yeast usually coexists peacefully with other microorganisms in a delicate microbial democracy.⁷

A yeast infection arises when an imbalance allows this yeast to stage a hostile takeover and multiply beyond its natural boundaries.

The most common strain is Candida albicans, responsible for more than 90% of vaginal yeast infections.⁸ But what actually disrupts the microbial balance enough to trigger an uprising?

1. Antibiotics: The Well-Meaning Destroyer

Antibiotics are lifesaving medications that kill bacteria—unfortunately, they're not selective about which bacteria they eliminate. They wipe out both harmful pathogens and the beneficial bacteria that naturally keep yeast populations in check.⁴

When your protective bacterial guards are eliminated, yeast multiplies rapidly in the newly available territory. This is why yeast infections frequently follow antibiotic treatment for completely unrelated conditions—your body's microbial ecosystem has been carpet-bombed, and Candida is the opportunistic colonizer that moves in first.

2. Weakened Immune System

Your immune system is the primary defense against fungal overgrowth. When it's compromised—due to conditions like HIV, autoimmune disorders, or treatments like chemotherapy—yeast can proliferate more easily.⁹

This doesn't mean everyone with a weakened immune system will develop yeast infections, but the risk increases significantly when your body's surveillance system is otherwise occupied.

3. Hormonal Changes: The Invisible Disruptor

Pregnancy, menstruation, birth control pills, and hormonal fluctuations can alter the vaginal environment in ways that favor yeast growth.¹⁰ Estrogen, in particular, affects vaginal pH and glycogen levels—when estrogen rises, so does glycogen, which serves as food for yeast.

This is why some women notice yeast infections correlating with specific points in their menstrual cycle, during pregnancy, or after starting hormonal birth control. The hormones themselves aren't "causing" the infection—they're altering the environment in ways that make fungal overgrowth more likely.

4. Diabetes and Blood Sugar Levels

Elevated blood sugar levels create an environment where yeast thrives.¹¹ Glucose in vaginal secretions essentially feeds Candida, allowing it to multiply more rapidly than your beneficial bacteria can control.

If you experience recurrent yeast infections alongside increased thirst, frequent urination, or unexplained fatigue, consider discussing diabetes screening with your doctor. Uncontrolled diabetes is a significant risk factor for persistent fungal infections.

5. Stress: The Invisible Saboteur

Stress impacts our bodies in countless ways, and unfortunately, increasing yeast infection risk is one of them.¹² Chronic stress elevates cortisol, suppresses immune function, and alters the balance of bacteria and yeast in the gut and vagina.

This is why some women notice yeast infections appearing during particularly stressful periods—your body's resources are redirected toward managing perceived threats, leaving less capacity to maintain microbial balance.

6. Non-Breathable Clothing and Moisture

Wearing tight clothing, synthetic underwear, or using non-breathable panty liners creates a warm, moist environment that promotes fungal growth.¹³ Yeast thrives in these conditions—think of it as creating a tropical vacation resort for Candida.

Staying in wet swimwear after swimming or keeping sweaty workout clothes on for extended periods compounds this effect. The moisture creates ideal conditions for yeast multiplication.

7. Sexual Activity: The Mechanical Trigger

Sexual activity can contribute to yeast infections, though it's important to understand that yeast infections are NOT sexually transmitted infections (STIs).¹⁴ Sex introduces friction, alters vaginal pH, and can transfer yeast between partners—but it doesn't "cause" infections in the way that bacteria cause gonorrhea or chlamydia.

Similar to the link between sex and UTIs, yeast infections can result from the mechanical and microbial disruptions that accompany intimacy. Certain lubricants, condoms with additives, and natural changes in vaginal pH after intercourse can all increase susceptibility.

The Difference Between Yeast Infections, UTIs, and BV

These three conditions share overlapping symptoms, which is why self-diagnosis is risky and professional evaluation matters.

Yeast Infections vs. Bacterial Vaginosis

Bacterial vaginosis (BV) is caused by bacteria, while yeast infections are caused by fungus.¹⁵ Both conditions share symptoms like itching and burning during urination. However:

• Yeast infections produce thick, white, odor-free discharge
• BV causes thin, white or gray discharge with a distinctive fishy odor, especially after sex

Yeast Infections vs. UTIs

Urinary tract infections (UTIs) occur when bacteria—usually E. coli—enters the urinary tract.¹⁶ Common UTI triggers include sexual activity, improper hygiene, and hormonal changes.

UTI symptoms are characterized by:

• Strong, persistent urge to urinate
• Burning sensation while urinating (similar to yeast infections)
• Dark, cloudy, bloody, or strange-smelling urine
• Pelvic pain or pressure

The burning sensation during urination can occur with both yeast infections and UTIs, which is why proper diagnosis is essential. A yeast infection causes burning because inflamed vaginal tissue makes urine contact painful—a UTI causes burning because bacteria are irritating the urethra and bladder itself.

Tips for Preventing Yeast Infections

Remember, some people are simply more prone to infections than others due to genetics, underlying conditions, or microbial composition. Prevention isn't about achieving perfection—it's about reducing risk factors where possible.¹⁷

1. Avoid Irritants

Steer clear of harsh soaps, scented products, and douching. These disrupt the natural vaginal balance and strip away protective bacteria, potentially triggering yeast overgrowth.¹⁸ Your vagina is self-cleaning and does not require aggressive intervention—in fact, aggressive intervention is often what causes the problems you're trying to prevent.

2. Wear Breathable Clothing

Opt for underwear made of natural fibers like cotton, which allows skin to breathe and wicks moisture away from the body. Avoid tight-fitting pants and leggings for extended periods—your vulva needs airflow, not compression.¹³

3. Change Out of Wet Clothes Promptly

Don't wear wet swimwear or sweaty workout clothes longer than necessary. Moist environments promote yeast growth. Change into dry clothes as soon as possible after swimming or exercising.

4. Manage Blood Sugar Levels

If you have diabetes, maintain good control over blood sugar levels. High glucose feeds yeast and promotes growth. Regular monitoring and appropriate treatment reduce infection risk.¹¹

5. Avoid Unnecessary Antibiotics

Overuse of antibiotics kills beneficial bacteria, allowing yeast to thrive unchecked. Only take antibiotics when prescribed by a healthcare professional, and always complete the full course as directed—but don't request them for viral infections or conditions that don't warrant antibiotic treatment.⁴

6. Consider Probiotics

Vaginal probiotics can help maintain a balance of healthy bacteria in the body. Certain probiotic strains—particularly Lactobacillus species—can lower your risk for recurring yeast infections by maintaining the acidic vaginal pH that inhibits Candida growth.¹⁹

When Prevention Isn't Enough

These prevention strategies reduce risk, but they don't guarantee immunity. Even if you're doing everything "right," yeast infections can still occur—because sometimes your body's microbial ecosystem tips into imbalance despite your best efforts.

Routine gynecological exams can help identify and address changes or imbalances before they escalate. If you're concerned about yeast infections, UTIs, or BV, schedule an appointment with your doctor rather than attempting prolonged self-treatment.

Yeast Infection Causes: Frequently Asked Questions

Can a male give a female a yeast infection?

Males can carry yeast on their penis and potentially transfer it to partners during sexual activity.¹⁴ Although yeast infections aren't STIs, they can be passed between partners through sexual contact.

Symptoms of yeast infections in males include itching, burning, redness, and foul-smelling discharge.²⁰ A male with an active yeast infection can transfer it to a female partner during intercourse.

Using condoms can reduce the risk of transferring yeast between partners. However, other factors—hormone changes, antibiotic use, weakened immune system—can make someone susceptible to infection after sex regardless of partner transmission.

Are yeast infections contagious?

Yeast infections are not "contagious" in the same way a flu or cold is. However, the yeast responsible for infection can be transferred between individuals under certain circumstances.¹⁴

Yeast can spread between sexual partners during vaginal, oral, or anal intercourse. Oral thrush can be passed through close contact like kissing, especially if one person has an active infection.

Importantly, just because yeast is transferred doesn't mean infection will result. Various factors increase susceptibility—primarily immune system function and existing microbial balance.⁵

Can certain foods cause yeast infections?

Food doesn't directly cause yeast infections, but dietary habits can influence microbial balance. Foods rich in probiotics promote a healthier gut microbial ecosystem, which influences vaginal microbiome composition.¹⁹

Interestingly, including foods rich in saturated fatty acids—like cheese—in your diet may actually hinder Candida growth in the gut.²¹ (This doesn't mean you should eat nothing but cheese, but it does mean you don't need to eliminate all fat or sugar from your diet in fear of triggering yeast infections.)

Can dirty fingers cause a yeast infection?

Fingers can introduce bacteria to the vagina, potentially triggering a yeast infection by disrupting microbial balance.²² Bacteria from unwashed hands can also lead to bacterial infections like BV and urinary tract infections.

Make sure you—and your partner—wash hands before any vaginal contact. This isn't prudish paranoia; it's basic microbial hygiene.

Can antibiotics cause a yeast infection?

Yes. Antibiotics disrupt the microbial balance by killing bacteria indiscriminately—including the beneficial bacteria that naturally keep yeast in check.⁴ When these protective bacteria are eliminated, yeast can multiply rapidly.

Probiotics may help maintain bacterial balance during antibiotic treatment, though evidence is still developing.²³ If you're prone to yeast infections and need antibiotics, discuss preventive strategies with your doctor.

Final Notes

Yeast infections are common, treatable, and not a reflection of your hygiene or sexual choices. They're fungal imbalances with identifiable triggers—antibiotics, hormones, stress, moisture, immune suppression, and microbial disruption.

Understanding these causes is crucial for prevention and management. For vaginal yeast infections specifically, supporting your overall urinary and vaginal health through strategic habits, appropriate clothing choices, and microbiome-conscious products can reduce recurrence risk.

Promoting holistic well-being—managing stress, maintaining healthy blood sugar, avoiding unnecessary antibiotics, supporting beneficial bacteria—creates an environment where your body's natural defenses can function optimally.

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The Good Kitty Approach

We created Good Kitty because women deserve products that support their entire urogenital ecosystem, not just address isolated symptoms. Our UTI prevention supplements work by maintaining the microbial balance and urinary tract integrity that make both UTIs and yeast infections less likely.

Because when your vaginal microbiome is thriving, when your pH is balanced, when your beneficial bacteria populations are strong—Candida doesn't get the opportunity to stage a hostile takeover in the first place.

Your body isn't broken. It's an ecosystem. And ecosystems respond to support.

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Note: References to "female," "women," "male," and "men" in this article refer to sex assigned at birth, not gender. This article does not replace medical advice. We recommend you seek treatment if you think you are experiencing a yeast infection, UTI, or any other infection.

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