Yeast infections are among the most common fungal infections affecting humans, particularly those assigned female at birth. These infections occur when the naturally present fungus Candida albicans grows excessively and disrupts the body’s natural balance. Though typically mild and easily treatable, yeast infections can become chronic or even life-threatening in severe cases such as invasive candidiasis.

This guide explores the different types, symptoms, causes, and treatments for yeast infections, as well as prevention tips and related health conditions.

Types of Yeast Infections

Yeast infections can appear anywhere Candida grows — from the mouth and throat to the vagina, skin, or bloodstream. Experts generally categorize them into two main types: local mucocutaneous infections and invasive candidiasis.

Local Mucocutaneous Infections

Local mucocutaneous infections affect the skin and mucous membranes, such as the mouth, throat, vulva/vagina, and sometimes the penis. These infections are usually less dangerous and can resolve with appropriate treatment within a week or two.

Common examples include:

  • Oral thrush – white patches on the tongue or inside the mouth.

  • Vaginal yeast infection – itching, burning, and abnormal discharge.

  • Cutaneous yeast infections – red, itchy rashes in moist skin folds.

Although not life-threatening, untreated mucocutaneous infections can cause considerable discomfort and may recur, especially if the immune system is weakened.

Invasive Candidiasis

Invasive candidiasis is a more severe infection that occurs when Candida enters the bloodstream or internal organs. One common form is candidemia — the presence of Candida in the blood.

Each year, around 25,000 cases of invasive candidiasis are reported in the U.S., and the mortality rate approaches 25%. People with weakened immune systems, such as those in hospitals or undergoing chemotherapy, are particularly vulnerable.

This type of infection may spread to organs like the liver, heart, brain, or kidneys, requiring aggressive intravenous antifungal therapy.

Yeast Infection Symptoms

Symptoms vary depending on the affected body part.

People with local infections usually experience:

  • Redness, itching, and soreness around the infected site

  • Discomfort during urination or sexual intercourse

  • Thick, white, cottage cheese–like vaginal discharge

  • White patches on the tongue or mouth in oral thrush

  • Cracking or inflammation at the corners of the mouth

Invasive candidiasis, on the other hand, may mimic bacterial or viral infections. Common signs include:

  • Persistent fever or chills

  • Fatigue or weakness

  • Symptoms that don’t improve with antibiotics

  • Organ-specific symptoms such as abdominal pain or confusion if the infection spreads

Because these symptoms overlap with other conditions, proper medical diagnosis is crucial.

What Causes Yeast Infections?

The yeast Candida albicans naturally resides in the mouth, gut, skin, and genital tract. It usually coexists with beneficial bacteria that keep it under control. However, certain conditions can disturb this balance and trigger fungal overgrowth.

Common Causes Include:

  • Antibiotic use – kills beneficial bacteria that normally suppress yeast growth.

  • Hormonal changes – pregnancy, menstruation, or birth control pills can increase vaginal yeast risk.

  • Uncontrolled diabetes – elevated blood sugar provides a growth environment for Candida.

  • Weakened immune system – from illness, HIV, or chemotherapy.

  • Warm, moist conditions – such as sweaty clothing or damp underwear.

  • Poor oral hygiene – especially in people using dentures.

When Candida multiplies unchecked, it transitions from harmless yeast to a pathogenic fungus capable of invading tissue and causing inflammation.

Risk Factors

Yeast infections are considered opportunistic infections, meaning they are more likely to occur when the immune system is compromised or when environmental conditions favor fungal growth.

Key risk factors include:

  • Antibiotic or steroid use

  • Chemotherapy or radiation therapy

  • Oral contraceptive pills or pregnancy

  • Smoking

  • Vitamin deficiencies (A, B6, or iron)

  • Diabetes mellitus

  • Long hospital stays or ICU treatment

  • Intravenous catheters and artificial heart valves

  • Dentures or dry mouth

  • Being an infant or an older adult

People with chronic illnesses or weakened immunity should be extra cautious about fungal infections.

Diagnosis

To confirm a yeast infection, a healthcare provider will evaluate your symptoms, medical history, and recent medication use, and may collect a sample from the affected area for laboratory testing.

For example:

  • Vaginal infections → swab of vaginal discharge

  • Oral infections → mouth swab

  • Invasive candidiasis → blood sample to detect Candida in the bloodstream

Test results usually take a few days. In some straightforward cases, doctors may begin treatment based on symptoms alone.

Treatments for Yeast Infections

Treatment depends on the infection type, severity, and immune status of the patient.

Local Mucocutaneous Infections

These are typically treated within one to two weeks using antifungal medications such as:

  • Topical creams (miconazole, clotrimazole, or tioconazole)

  • Suppositories or vaginal tablets

  • Oral antifungals (fluconazole)

If infections recur frequently, your doctor may recommend a longer treatment plan or an alternative antifungal medication.

Common OTC options:

  • Monistat (miconazole)

  • Gyne-Lotrimin (clotrimazole)

  • Vagistat or Gyno-Trosyd (tioconazole)

  • Terazol (terconazole)

Prescription options:

  • Diflucan (fluconazole)

  • Nystatin (for oral thrush)

  • Butoconazole (Gynazole or Femstat)

Invasive Candidiasis

This serious condition requires intravenous (IV) antifungal therapy and hospitalization. Treatment generally continues for two weeks after blood tests confirm the infection has cleared.

If the fungus has spread to organs, bones, or the nervous system, a longer course may be necessary.

Unfortunately, antifungal resistance is a growing issue. According to the CDC, 7% of Candida samples are resistant to fluconazole, underscoring the importance of prevention.

Prevention

Preventing yeast infections starts with maintaining a healthy balance of microorganisms in your body.

General Prevention Tips

  • Maintain good hygiene, especially oral and genital care.

  • Wear breathable cotton underwear and avoid tight or damp clothing.

  • Avoid unnecessary antibiotic use.

  • Limit sugar intake, as yeast thrives on glucose.

  • Change out of wet clothes promptly after swimming or exercise.

For High-Risk Individuals

Certain people may receive prophylactic antifungal medications, including:

  • ICU patients

  • Organ transplant recipients

  • Chemotherapy patients

  • People with low white blood cell counts

  • Premature infants or those with low birth weights

By keeping your immune system strong and managing health conditions, you can greatly reduce your risk of recurrent yeast infections.

Related Conditions

Some chronic illnesses increase susceptibility to yeast infections:

  • HIV/AIDS: Weakens immune defense, making fungal infections harder to control.

  • Diabetes: Poorly managed blood sugar promotes fungal overgrowth.

  • Cancer: Chemotherapy and radiation suppress immune response, raising infection risk.

In such cases, consistent monitoring and preventive antifungal therapy may be necessary.

Living With Yeast Infections

Most yeast infections are mild and clear up within one or two weeks of treatment. Maintaining good hygiene and balanced nutrition helps prevent recurrences.

For invasive candidiasis, the prognosis is more serious, but timely treatment can save lives. Even after recovery, patients should continue monitoring their health and follow medical advice closely.

If you experience recurring infections or symptoms that don’t improve, consult your healthcare provider. Long-term relief often requires addressing underlying causes such as hormonal imbalance, medication use, or weakened immunity.

A Quick Review

Yeast infections happen when the Candida fungus grows excessively in the body. Most cases are localized and easily treated with antifungal creams or oral medication, but invasive candidiasis can be life-threatening.

Maintaining hygiene, supporting your immune system, and seeking medical care for persistent symptoms are essential to keeping infections under control.