Fungal skin infections are caused by certain types of fungus, or excessive growth of normally harmless types. Fungal skin infections usually affect your skin because they live off keratin, a protein that makes up your skin, hair and nails. Most fungal skin infections can be treated effectively.
Types of fungal skin infections and the symptoms they can cause
Fungal skin infections are divided into groups, depending on what type of organism is involved. The full name depends on where the infection is found on your body. Some common fungal skin infections are listed below.
Dermatophyte infections
Most basic fungal skin infections are caused by dermatophytes — types of fungi that cause skin, nail and hair infections. They are very common. Dermatophyte infections include the following:
- Athlete's foot (tinea pedis and tinea manuum). Around one in four adults have athlete's foot (tinea pedis) at some time in their lives. It can be caused by a combination of fungi and bacteria, which makes your skin itchy, dry, scaly and red. Sometimes it causes blisters and cracked skin. It’s especially common between your toes. You often pick up athlete's foot from coming into contact with contaminated skin left behind in swimming pools, showers and saunas. If you don't wash your hands after touching a contaminated area, it can spread to your hands where it's known as tinea manuum. This mostly affects the creases on your palms and sides of your fingers.
- Nail infections. Onychomycosis is the name for any fungal nail infection. Tinea unguium (ringworm of your nails) is a common infection. Your nails become malformed, thickened and crumbly. Not all nails affected like this are caused by fungal infections, but it's a common cause. Toenail infections are commonly linked with athlete's foot. Your fingernails can be affected too.
- Ringworm of the groin (tinea cruris). This is often called 'jock itch' because it occurs in sportspeople and is common among young men. It causes an itchy, red rash in your groin and the surrounding area and is usually seen in men who’ve been sweating a lot. Often you’ll also have athlete's foot, as the infection can be spread by scratching your groin after scratching your infected feet.
- Ringworm on the body (tinea corporis). This often affects exposed areas of your body, such as your abdomen (tummy) or your limbs, causing red raised or flat patches and rings that can merge, grow and spread from the centre. The rings are scaly at the edge surrounding clear skin in the middle.
- Ringworm of the scalp (tinea capitis). This usually affects young children. It can cause hair loss and inflammation of the affected area. You can be infected by this fungus without developing any symptoms, and become a carrier instead, spreading the infection to others, sometimes for years.
Yeast infections
Yeast infections include the following:
- Thrush. The fungus Candida albicans usually lives naturally in us and rarely causes problems. However, in certain situations, such as if you're ill, have poorly controlled diabetes, are pregnant or using antibiotics, the fungi multiply and can cause thrush symptoms.
Thrush can affect your mouth and tongue, areas lined with a mucus membrane such as your vagina, and other moist, folded skin. Thrush infection often looks like small white patches, which leave a red mark when rubbed off. In adults, vaginal thrush can cause itchiness and a thick, white discharge. Thrush sometimes affects men, causing a painful red rash on the head of the penis (glans). It also commonly affects newborn babies in the mouth (oral thrush) where the white patches may be mistaken for breast or formula milk. It isn't usually serious, but babies with thrush in their throats may stop feeding properly. Babies may also develop thrush in the nappy area.
- Intertrigo. This is also caused by the normally harmless fungus Candida albicans, which lives on your skin and in your digestive system. It affects areas where skin touches skin and the environment is warm and moist, such as your armpits, groin, and under heavy breasts or fat folds. It can cause itching, soreness, spots and scales, creating a white-yellow curd over the infected area.
- Pityriasis versicolour. This infection causes dark patches to form on pale or untanned skin and light patches on tanned or darker skin. Another name for this condition is tinea versicolor (versicolor means 'of various colours').
Causes of fungal skin infections
You're more at risk of getting a fungal skin infection if you:
- have recently taken a course of antibiotics
- are taking steroids
- have high blood sugar levels (for example, if you have uncontrolled diabetes)
- are overweight
- have had fungal skin infections in the past
- have a weakened immune system caused, for example, by cancer or HIV/AIDS.
Moist skin encourages fungal skin infections. This means you're more likely to pick one up if you don't dry your skin properly after sweating or bathing, or if you wear tight clothes that don't allow sweat to evaporate. Damage to the surface of your skin, such as a cut or graze, can also encourage fungi to grow.
Fungal infections inside your body can cause more serious health problems than those on your skin. These infections only affect people whose immune systems aren't working properly — either as a result of an illness such as HIV/AIDS, or because you're taking medicines that suppress your immune system.
How do fungal skin infections spread?
Fungal skin infections can be spread from person to person. For example, athlete's foot is thought to be spread in communal areas, such as gyms and swimming pools. Contact with bed sheets or towels and personal items such as hairbrushes can also spread fungal infections. It's also possible to catch some fungal infections from animals such as cats or dogs, and, more rarely, cattle. Ringworm is occasionally caught this way.
Diagnosis of fungal skin infections
Your GP will ask about your symptoms and examine you. He or she will look at the appearance and location of your rash. They may also take a skin scraping, or a fragment of your nail or hair, and send it to a laboratory for testing, to confirm the diagnosis.
Treatment of fungal skin infections
As most fungal skin infections are on the surface of your skin, you’ll usually be able to apply topical antifungal treatments directly onto your skin in the infected area.
There are a variety of treatments available in the form of creams, lotions and medicated powders. Some treatments are available over-the-counter from a pharmacist. For example, there are sprays available for treating athlete's foot and antifungal shampoos for scalp infections. Ask your pharmacist for advice.
However, if the infection covers quite a large area of your skin, or affects your nails or scalp, your GP may give you a prescription for a stronger medication, which is often in tablet form.
These treatments are usually effective. They can occasionally cause side effects which may include skin irritation for topical treatments or an upset stomach for oral medicines. It isn't unusual for your infection to return, even when it seems to have been treated. You’ll usually be advised to keep using topical treatments for two weeks after symptoms have disappeared. You may need to take some treatments for a few weeks, or up to 18 months for toenail infections.
If you're buying an over-the-counter antifungal treatment, you need to be sure that you have a fungal infection. Sometimes a new rash may look like a previously diagnosed fungal infection. But if there is any doubt about your diagnosis, or if over-the-counter treatments don't work, contact your GP.
Prevention of fungal skin infections
There are some steps you can take to reduce your risk of getting a fungal skin infection, such as:
- drying your skin carefully after bathing
- wearing loose fitting clothes and underwear
- choosing cotton socks and natural fibre underwear to allow your skin to breathe
- not sharing towels, hair brushes, and combs
- washing bed linen and clothes often to get rid of fungal spores
- throwing away or disinfecting pillows, hats, combs or scissors if someone in your family has scalp ringworm
- always wearing thongs or plastic shoes in communal areas such as swimming pools and change rooms
- alternating shoes every two or three days so that they have time to dry out (to help prevent athlete's foot)
- wearing synthetic fibres that 'wick' the sweat away from the body, helping to keep your skin dry if you're exercising.
If you have diabetes, you need to keep your blood sugar levels under control, as high blood sugar levels can increased your risk of developing bacterial and fungal skin infections.
Further information
Australasian College of Dermatologists
www.dermcoll.asn.au/
Sources
Clinical Knowledge Summaries. Fungal skin infection – body and groin. [online] London: National Institutes for Health and Clinical Excellence. 2009 [last updated Aug 2010, accessed 4 Jul 2011] Available from: http://www.cks.nhs.uk/fungal_skin_infection_body_and_groin
Clinical Knowledge Summaries. Fungal skin infection – foot. [online] London: National Institutes for Health and Clinical Excellence. 2009 [last updated Aug 2010, accessed 4 Jul 2011] Available from: http://www.cks.nhs.uk/fungal_skin_infection_foot
Clinical Knowledge Summaries. Fungal nail infection (onychomycosis). [online] London: National Institutes for Health and Clinical Excellence. 2009 [last updated May 2009, accessed 4 Jul 2011] Available from: http://www.cks.nhs.uk/fungal_nail_infection
Clinical Knowledge Summaries. Fungal skin infection – scalp. [online] London: National Institutes for Health and Clinical Excellence. 2009 [last updated May 2009, accessed 4 Jul 2011] Available from: http://www.cks.nhs.uk/fungal_nail_infection
Clinical Knowledge Summaries. Candida – skin. [online] London: National Institutes for Health and Clinical Excellence. 2008 [last updated Aug 2010, accessed 4 Jul 2011] Available from: http://www.cks.nhs.uk/candida_skin
Clinical Knowledge Summaries. Candida – female genital. [online] London: National Institutes for Health and Clinical Excellence. 2007 [last updated May 2010, accessed 4 Jul 2011] Available from: http://www.cks.nhs.uk/candida_female_genital
Clinical Knowledge Summaries. Candida – oral. [online] London: National Institutes for Health and Clinical Excellence. 2009 [last updated Oct 2009, accessed 4 Jul 2011] Available from: http://www.cks.nhs.uk/candida_oral
Martin K Ernst E. Herbal medicines for treatment of fungal infections: a systematic review of controlled clinical trials. Mycoses. 2004; 47: 87-92.
Roberts D Taylor W Boyle J. Guidelines for treatment of onychomycosis. British Journal of Dermatology. 2003; 148: 402-410.
Simon C Everitt H Kendrick T. Oxford Handbook of General Practice. 2nd ed. Oxford: Oxford University Press. 2005; p.648.
Victorian Government Health Information. Ringworm or tinea. [online] Melbourne, VIC: State Government of Victoria. [Last updated 15 Jan 2008, accessed 3 Jul 2011] Available from: http://www.health.vic.gov.au/ideas/bluebook/ringworm
Last published: 30 July 2011
