Fungal infections



Superficial fungal infestations occur as infections of the skin and nails. They are caused by fungi that are everywhere around us. Fungi thrive in warm, moist conditions.

Fungal infection of a person’s scalp or body is sometimes called ringworm. There are, however, many forms of superficial fungal infection of the skin specific to the body areas that they affect.

Tinea versicolor is a fungal skin infection that appears on the upper arms, chest and back.

Fungal infection of the nails is known as onychomycosis (in some cases tinea unguium). When a fungus invades a fingernail or toenail, the nail (nail plate), as well as the skin under the nail (nail bed) is affected.

Candida albicans is a yeast that everyone has in the gut. Under certain conditions it invades the skin or mucous membranes. When it affects the mouth, it is called oral thrush.

Fungi can be passed on quite easily from one person to another, but this does not mean that the fungus will necessarily infect the other person. Some people are more susceptible to fungal infections than others. In these people the presence of fungi on the body will result in fungal infections.

Note deep fungal infections and systemic fungal infections are not dealt with here.


Fungi exist naturally in our environment, as well as on and in our bodies. They do not normally cause disease.

Fungi can be passed on quite easily from one person to another, but this does not mean that the fungus will necessarily infect the other person. Some people are more susceptible to fungal infections than others, e.g. people whose immune systems do not work as well as they should. In these people the presence of fungi on the body will result in fungal infections.

Fungi can live on people, objects or animals for several months, and can be transferred in this way.

The following types of fungal infestations are discussed:

  • Ringworm (and related superficial fungal infections of the skin)
  • Pityriasis/Tinea versicolor
  • Nail infections
  • Oral thrush


Fungal infection of a person’s scalp or body is sometimes called ringworm. This is because of the round or ring-shape often observed. No worm is involved! Many subtypes of fungal skin infection are named according to their location, as follows:

  • Scalp -  tinea capitis
  • Groin – tinea cruris or dhobi/jock itch
  • Beard – tinea barbae
  • Hands – tinea manuum
  • Feet – tinea pedis or athlete’s foot
  • Body – tinea corporis
  • Face – tinea faciei/facialis

Fungi thrive in warm, moist areas of the body, such as the groin or feet. Most cases of fungal skin infection are caused by a dermatophyte (skin fungus) called Trichophyton rubrum. Dermatophytes attack the body’s outer tissues that contain keratin (a protein found in skin, nails and hair), but cannot invade the cells.

Tinea/Pityriasis versicolor

Tinea versicoloris a fungal skin infection that appears on the upper arms, chest and back. It is a result of overgrowth of Malassezia furfur.

Nail infections

Three types of fungi are responsible for fungal nail infections (onychomycosis):

  • Dermatophytes (mostly toenails)
  • Yeast – grow in areas of warm, moist skin, such as skin folds, and on the fingernails
  • Moulds or non-dermatophytes – on the skin and nails (these organisms commonly grow in soil)

Toenails, in particular, offer fungi warm, moist conditions.

Toenails injured by too much trimming or by ingrowing may be prone to infection with fungi. A person whose feet perspire excessively runs a greater risk of fungal infection of the toenail. The possibility of fungal infection is greater if you wear socks or stockings made of synthetic fibres, or shoes with rubber instead of leather soles, or if you walk barefoot around swimming pools, showers and locker rooms. Toenails also grow more slowly, giving the fungal infection time to develop.

Fungal infections of the fingernails may result from overexposure to water and detergents. The moisture that gets trapped under the nails encourages fungal growth.

Nails that are continually exposed to a warm, moist environment may develop a fungal infection on the nail or under its outer edge. When the nail becomes separated from the skin underneath it, the condition is called onycholysis.

Oral thrush

The Candida albicans organism causes thrush. Babies with thrush have usually contracted it during delivery, when they passed through a vagina infected with Candida. Symptoms appear as oral thrush within seven to 10 days after birth.

Thrush may develop after a viral upper respiratory infection, infectious mononucleosis (glandular fever) or irritation caused by dentures.

The condition may occur after treatment with antibiotics. During the treatment, the antibiotics kill all the normal bacteria in the mouth, giving the Candida fungi the opportunity to flourish.

People are more prone to thrush if they are chronically ill, malnourished or have severely impaired immunity.

Candidacan sometimes lead to infection of the skin in other areas of the body.


The symptoms of the following fungal infestations are discussed:

  • Ringworm of the skin
  • Ringworm of the scalp and beard
  • Ringworm of the groin
  • Ringworm of the hand
  • Athlete’s foot
  • Tinea versicolor
  • Nail infections
  • Oral thrush

Ringworm of the skin

  • Red patches with scaling, pustules and crusts
  • Itchy rash that spreads rapidly
  • Rash resembling a ring, with a clear centre and elevated, red scaly border
  • Patches of rash with a border that is not clearly distinguishable (some cases)
  • Exacerbation of the rash after exposure to the sun (uncommon)

Ringworm of the scalp and beard

  • One or more round or oval patches of baldness on the scalp, beard or moustache
  • Hair loss (temporary or permanent)
  • Scalp ringworm is almost exclusively seen in young children
  • Flakes resembling dandruff on the hair
  • Irritation of the scalp, beard or moustache
  • Crusted, broken or matted hair
  • Black dots on the scalp where hair has broken off at the roots (less common)
  • Swollen lymph nodes in the neck (occasional)

Ringworm of the groin

  • A rash in the groin, in skin folds, and on inner thighs or buttocks (usually not on the penis or scrotum)
  • A well-defined border around the rash, with scaling or tiny blisters
  • A red-brown centre inside the rash
  • Simultaneous occurrence of athlete’s foot (some cases)

Ringworm of the hand

  • A rash on the palm or back of the hand (rare)
  • Rash on palm: may be dry and scaly
  • Rash on back of hand: may be scaly, with tiny blisters around the edges
  • Fingernail infection (some cases)
  • Simultaneous occurrence of athlete’s foot (some cases)

Athlete’s foot

  • Usually involves the spaces between the 3rd, 4th and 5th toes.
  • Skin is red, scaly and macerated (whitish colour due to moisture).
  • The toenails may show signs of fungal infection.

Tinea versicolor

  • Rash consisting of white, scaly spots on the upper arms, chest and back

Some people with fungal infections have an allergic reaction (called id reaction) on a different part of the body. In ringworm of the scalp, the id reaction usually occurs on the face.

Nail infections

Symptoms may include the following:

  • A distinct white or yellow spot on the nail that gradually spreads over the entire nail
  • Yellow streaks in the nail bed and on the underside of the nail (nail plate)
  • White spots or white streaks on the nail surface
  • White nail base
  • A soft and powdery nail surface
  • Opaque nail
  • Discoloured, damaged, splitting, brittle, thickened and rough nails
  • Cracking or crumbling of nails
  • Build-up of debris (nail fragments and pieces of skin) under the nail
  •  Discolouration of the entire nail and separation of the nail from the nail bed (onycholysis) – severe infections
  • Red, itchy or swollen surrounding skin
  • Athlete’s foot occurring simultaneously

With Candida onychomycosis, the symptoms vary. This infection usually occurs in the fingernails. The following symptoms may appear:

  • Opaque, greenish or brownish nails
  • Oddly shaped nails
  • Thick nails
  • Infection of the nail fold skin may cause pain

Oral thrush

  • Curd-like white patches inside the mouth, on the tongue, palate and around the lips
  • Red, inflamed areas underneath the white surface, with slight bleeding when attempting to scrape off the white patches
  • Cracked, red, moist areas of skin at the corners of the mouth
  • Fussiness, irritability, and poor feeding in infants if the infection is painful (rare)



Ringworm commonly infects children. Ringworm of the groin (dhobi itch) is seldom seen in women.

Nail infections

Only about 50% of all nail diseases and disorders are due to fungal infection. More adults than children get fungal nail infections. Of all fungal nail infections, about 80% are of the big toenail and 20% of the fingernails. Men get infections caused by dermatophytes more often than women do, and women get yeast infections more often than men do. Moulds are more prevalent in humid, tropical climates and dermatophytes more in mild climates.

Oral thrush

Thrush infects two to five percent of newborn babies.


The course of the following fungal infestations is discussed in this section:

  • Ringworm
  • Nail infections
  • Oral thrush


The first sign of ringworm of the scalp may be dandruff-like flakes appearing on the hair. Round and/or oval bald patches may appear. The skin may feel itchy and may be red and peeling. The rash may gradually spread over a large area if left untreated. Once the hair is infected, it becomes brittle and breaks off near the root, resulting in bald spots. If treated early, the baldness is temporary. The skin of the infected area may become very tender if swollen areas and blister-like bumps with pus develop. The blisters may become infected. If left untreated, ringworm of the scalp or beard may result in scarring and permanent hair loss.

Ringworm of the skin starts as a small patch that is itchy, red or scaling. The rash may spread over a large area. Symptoms are aggravated by clothing rubbing against the rash, and by sweat, heat and humidity. As the infection becomes worse, the ring-like pattern and red-brown colour become more distinct. If left untreated, blisters and cracks may become infected with bacteria. Ringworm can spread to other parts of the body. 

Nail infections

Untreated nail infections can lead to unsightly and painful nails and fingers. If left untreated, fungal nail infections may become worse, other parts of the nails and/or other nails may become infected and the skin around the nail becomes infected. Nails may become odd in shape and appearance, even after treatment.

Some fungal nail infections progress very slowly, but others develop rapidly, especially in warm and damp conditions.

Oral thrush

Thrush may recur in people with chronic illnesses and those with impaired immunity. The oral thrush fungus may also spread to other parts of the body, such as the oesophagus, causing Candida oesophagitis.

Risk Factors


  • Previous fungal infection
  • Impaired immune system, owing to illnesses such as diabetes, cancer or AIDS
  • Living in a warm, damp climate
  • Keeping skin damp or wet for long periods of time
  • Wearing tight-fitting clothes and shoes
  • Contact with animals and people who may carry the fungi without necessarily being infected themselves
  • Contact with objects which have the fungi on them, for example shoes, hats, towels and bed linen
  • Men are more prone to ringworm of the groin.

Nail infections

  • As people get older, their nails thicken and grow more slowly, making them more susceptible to infection.
  • A person whose feet perspire excessively is at greater risk of getting toenail infections.
  • The likelihood of infections increases if one wears socks or stockings made of synthetic fibres; tight, ill-fitting shoes; shoes with rubber instead of leather soles; or if one walks barefoot around swimming pools, showers and locker rooms.
  • Poor blood circulation due to disease may increase the risk of infection.

Oral thrush

  • Newborn babies
  • People using antibiotic medication
  • The chronically ill (such as diabetics)
  • The elderly
  • People using corticosteroid drugs or other medications that suppress the immune system
  • Those with weak immune defences (such as people with AIDS)

When to see a doctor


Call your doctor if:

  • The skin on the scalp, under the beard or on the body is scaling, peeling, itchy, red and swollen, or if blister-like bumps with pus develop
  • There are dandruff-like scales that do not disappear after two weeks of treatment with anti-dandruff preparations
  • There is patchy hair loss
  • There are signs of a bacterial infection, such as increased pain, swelling, redness, tenderness and heat; red streaks extending from the area; a discharge of pus; and a fever with no other identifiable cause
  • There is no improvement after two weeks of treatment with non-prescription medication
  • The infection is spreading
  • There is persistent, severe or recurring infection

Nail infections

Call your doctor if:

  • A nail is severely discoloured, damaged or thickened
  • There is a build-up of pieces of skin and nail fragments under the nail
  • There are signs of a bacterial infection such as increased pain, swelling, redness, tenderness and heat; red streaks extending from the area; a discharge of pus; and a fever with no other identifiable cause
  • The infection is spreading
  • The condition is painful

Oral thrush

Call your doctor if:

  • Curd-like white patches appear inside the mouth
  • Mouth irritation prevents a baby from feeding
  • In addition to the above, there is difficulty swallowing


Ringworm and Pityriasis versicolor

Ringworm is diagnosed on the basis of a medical history and an examination of the infected area. In addition, tests may be done on a sample of the infected hair or skin to confirm the diagnosis:

  • A KOH (potassium hydroxide) preparation can determine if a fungus is causing the condition. This test is done in a clinic or a doctor’s surgery. This involves the doctor scraping the skin with a blade and examining the debris under a microscope.
  • A fungal culture may be done to determine if a fungus is causing the condition and, if so, which fungus it is.
  • Wood’s Light Examination may be undertaken to determine the presence of fungi on the scalp or beard. In this test, a fluorescent light is shone onto the hair because some fungi will make the hair fluoresce or glow in the light.
  • If secondary infection is suspected, a bacterial culture may be done.
  • Rarely, the doctor may take a skin biopsy for a microscopic study.

Nail infections

Fungal nail infections are diagnosed on the basis of a medical history, a test of a sample of the debris under the nail, or a nail sample scraped or cut from the nail.

  • A KOH (potassium hydroxide) preparation can determine if a fungus is causing the condition. This test is done in a clinic or a doctor’s surgery.
  • A fungal culture may be done to determine if a fungus is causing the condition, and which fungus may be the cause. This is performed on a specimen of nail (a clipping is taken).
  • Rarely, the doctor may take a skin biopsy for a microscopic study.

Oral thrush

Diagnosis is based on a medical history and specific information about:

  • Diabetes
  • HIV
  • Chronic illnesses
  • Recent respiratory infections
  • Infectious mononucleosis (glandular fever)
  • Diet
  • Recent use of antibiotics
  • Recent use of medications that suppress the immune system

In babies a nappy rash, caused by the same fungus, may be present.

Examining the mouth and scraping the surface of the thrush to see if there is bleeding usually suffice for making the diagnosis. In addition, the following tests may be done:

  • A scraping of the mucosa, for a fungal culture
  • Blood and other tests, to determine undiagnosed medical conditions such as diabetes, cancer and HIV infection



Home treatment of fungal infections focuses on preventing re-infection and spreading of the infection. Floors and soft furnishings should be vacuumed or steam-cleaned. Dilute bleach can be used to clean floors that may be contaminated. Pets should be checked by your veterinarian for signs of infection.



Medication for the treatment of ringworm consists of non-prescription anti-fungal preparations that can be applied to the infected area. Treatment often takes weeks, and should continue for some time after visual resolution. Treatment should extend beyond the visible border of the lesion. Medication to be taken orally may also be prescribed. Secondary infection may require antibiotic treatment. Ringworm of the scalp is usually treated with griseofulvin, which is an oral medication that your doctor must prescribe. Selsun or ketoconazole shampoo may help, but is not sufficient treatment. Treatment for athlete’s foot is now available as a once-off dose.

Nail infections

Potent oral medications are now available. These medications are absorbed into a person’s blood at levels that can penetrate a nail and destroy the fungus. Treatment usually lasts for 6-12 weeks. These medications are itraconazole, terbinafine and fluconazole, and actively kill the fungus. In some cases of fungal toenail infection, griseofulvin may be used to prevent the fungus from spreading while the new toenail grows out, a process that can take at least a year. This medication does not kill the fungus.  It is important to note that all of these drugs may interact with many other types of medication.

An anti-fungal cream may be prescribed to confine the infection. In some cases, a cortisone cream may also be added. In cases where the nails are very thick, creams containing urea may be used to thin the nail out and make treatment more effective.

It is important to be patient, as it takes many months for nails and especially toenails to grow out.

Oral thrush

Anti-fungal medications such as nystatin, clotrimazole, ketoconazole and fluconazole are used for treating thrush. Nystatin is a suspension that is swished around the mouth and then swallowed. Clotrimazole can be taken in lozenge form. Ketoconazole or fluconazole must be taken orally for seven to 10 days. Gentian violet may be used to paint an infected area.


Surgery is not used for ringworm or oral thrush.

In the case of fungal nail infections, removal of the nail may be indicated if the infection is severe and painful or if oral anti-fungal medication would interfere with other medication you may be taking, for example blood thinners, seizure medication and some allergy medication. In the case of recurrent infections, the nail root may be removed permanently. Surgery should only be used as a last resort.



  • Avoid close contact with people who have ringworm of the scalp, beard or skin.
  • Avoid petting animals that have bald or mangy spots on their coats.
  • Wear fresh underwear and socks daily.
  • Do not share hats, coats, brushes and bed linen with someone who has ringworm.
  • Disinfect sports equipment like mats.
  • Avoid the use of products such as pomades and perfumed hair ointment that could promote the growth of fungi.
  • Keep your skin clean and dry.
  • A person may be a carrier of fungi without even being aware of it. Therefore all the family members of an infected person should be tested for fungal infection.
  • If you have athlete’s foot, put your socks on before your underwear to avoid infecting your groin area.

Nail infections

  • Keep the nails clean and dry. Dry the feet well after a bath or shower, especially between the toes.
  • Wear open shoes whenever possible.
  • Change socks at least daily, or more often if your feet perspire excessively.
  • Do not over-trim nails, or pick at and poke around the toenails; prevent minor injury which might provide an entry point for fungi.
  • Do not wear tight or ill-fitting shoes.
  • Try not to wear the same pair of shoes for two days in a row. Give a pair of shoes 24 hours to dry out.
  • Do not share shoes or nail clippers with someone else.
  • Do not walk barefoot in public or shared showers or locker rooms. Wear shower sandals or shower shoes.
  • Treat other infections such as athlete’s foot.

Oral thrush

  • Follow a healthy diet.
  • Use antibiotics only as prescribed by a doctor. Taking probiotics or eating yoghurt may help to prevent thrush.
  • Visit the dentist if you have an irritation caused by dentures.
  • Pregnant women should be checked for vaginal thrush to prevent oral thrush infection of their newborn babies.

Previously reviewed by Prof H.F. Jordaan

Updated by Dr B Tod MBBCh (Wits), July 2011

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