Candidiasis (Candida Yeast Infections)

What Candida is

Candida is a yeast, a type of fungus. Most people carry it on their skin and in their mouth, gut and vagina without problems, because helpful bacteria and the immune system keep it in check. Candidiasis develops when something tips that balance.

Candida albicans causes most infections. Other species, such as C. glabrata, C. parapsilosis and the multidrug-resistant Candida auris, are increasingly common, especially in hospitals.

Types of candidiasis

Vaginal candidiasis (vaginal yeast infection)

About 3 in 4 women have at least one in their lifetime. Symptoms:

• itching and burning of the vulva and vagina
• thick, white, cottage-cheese-like discharge, usually without a strong smell
• redness and swelling of the vulva
• pain during sex or when urine touches irritated skin

See vaginal yeast infection.

Oral thrush (oropharyngeal candidiasis)

• creamy white patches on the tongue, inner cheeks, gums or throat that can be wiped off, leaving red, sore areas
• cotton-mouth feeling, loss of taste, soreness
• cracking at the corners of the mouth (angular cheilitis)

Common in babies, denture wearers, people using inhaled steroids, and those with diabetes, HIV or on chemotherapy. See oral thrush.

Esophageal candidiasis

Pain on swallowing and difficulty swallowing, mostly in people with HIV, cancer or other immune suppression. It needs tablets rather than local treatment. See esophageal candidiasis.

Skin candidiasis

• Intertrigo: red, moist, sometimes itchy rash in skin folds (under breasts, groin, armpits, between buttocks, under a belly fold), often with small "satellite" spots at the edges
• Diaper rash: bright red rash in the diaper area that involves skin creases, with satellite spots, often lasting more than 3 days. See diaper dermatitis.
• Balanitis: red, sore, itchy head of the penis, more common in uncircumcised men and men with diabetes
• Paronychia and nail infection: swollen, red nail folds and thickened nails, often in people whose hands are frequently wet

Invasive candidiasis

Candida enters the bloodstream (candidemia) and can spread to the heart, eyes, bones and organs. It is a leading cause of bloodstream infection in hospitals. Risk factors include central venous catheters, intensive care stays, abdominal surgery, broad-spectrum antibiotics, intravenous nutrition, dialysis and severe immune suppression. It causes fever and chills that do not respond to antibiotics and can be life-threatening. See invasive candidiasis.

Causes and risk factors

• antibiotics, which kill the bacteria that normally keep Candida in check
• diabetes, especially when blood sugar is poorly controlled
• pregnancy and estrogen-containing contraceptives
• corticosteroids, including inhaled steroids for asthma
• weakened immune system: HIV, chemotherapy, organ transplant medicines
• dentures, dry mouth and smoking (oral thrush)
• warmth, moisture and friction in skin folds, tight clothing and obesity
• SGLT2 inhibitor diabetes medicines such as empagliflozin and dapagliflozin, which increase sugar in urine (genital infections)

Candidiasis of the genitals is not considered a sexually transmitted infection, although it can occasionally pass between partners.

Diagnosis

Common forms are usually diagnosed by appearance and symptoms. Tests are used when the diagnosis is uncertain, infections recur or treatment fails:

• microscopy of a scraping or swab, which shows yeast and hyphae
• culture to identify the species and test drug sensitivity
• vaginal pH, which is normal (4.5 or lower) in yeast infection, unlike bacterial vaginosis or trichomoniasis
• endoscopy for suspected esophageal candidiasis
• blood cultures and other tests for invasive candidiasis
• blood glucose or HbA1c and HIV testing for recurrent or unexplained infections

Treatment

Fluconazole interacts with many medicines, including some statins and blood thinners, so a pharmacist or doctor should check before it is taken.

Prevention

• use antibiotics only when necessary
• keep blood sugar well controlled
• rinse your mouth after using a steroid inhaler, and clean dentures nightly
• keep skin folds clean and dry, wear breathable cotton clothing and change out of wet swimwear promptly
• change diapers frequently and allow diaper-free time
• avoid douching and scented feminine products
• evidence for probiotics and yogurt in preventing yeast infections is limited

Frequently asked questions

What is candidiasis?

Candidiasis is an infection caused by overgrowth of Candida yeast, which normally lives harmlessly on the body. It most often affects the vagina, mouth, skin folds, diaper area and nails. In rare cases, it spreads through the bloodstream, mainly in hospitalized or immunocompromised people.

What are the different types of candidiasis?

The main types are vaginal candidiasis, oral thrush, esophageal candidiasis, cutaneous candidiasis (skin folds, diaper rash, penile and nail infections) and invasive candidiasis, which affects the bloodstream and internal organs.

What causes candidiasis?

It develops when the normal balance of microbes or the immune system is disturbed. Common triggers include antibiotics, diabetes, pregnancy, corticosteroids, a weakened immune system, dentures, and warm, moist skin folds. Some diabetes medicines also raise the risk of genital yeast infections.

How is candidiasis treated?

Most infections respond to antifungal creams, pessaries, lozenges or a short course of fluconazole tablets. Recurrent vaginal infections may need months of weekly treatment. Invasive candidiasis needs hospital treatment with intravenous antifungal medicines.

Is candidiasis contagious?

Candidiasis is not usually considered contagious, because most people already carry Candida. It can occasionally pass between sexual partners or from mother to baby during breastfeeding. Candida auris is an exception: it can spread in hospitals and nursing homes.