Am Fam Physician. 1998;58(1):177-178
See related article on tinea infections.
What is tinea?
Tinea is a fungus that can grow on your skin, hair or nails. As it grows, it spreads out in a circle, leaving normal-appearing skin in the middle. This makes it look like a ring. At the edge of the ring, the skin is lifted up by the irritation and looks red and scaly. To some people, the infection looks like a “worm” is under the skin. Because of the way it looks, tinea infection is often called “ringworm.” There really isn't a worm under the skin, though.
How did I get tinea?
One of every five persons gets a fungus infection at some time. You can get a fungus infection by touching a person who has one. Some kinds of fungus live on damp surfaces, like the floors in public showers or locker rooms. You can easily pick up a fungus there. You can even catch a fungus infection from one of your pets. Dogs and cats, as well as farm animals, can be infected with a fungus. Often this infection looks like a patch of skin where fur is missing.
What areas of the body are affected by tinea infections?
Fungus infections are named for the part of the body they infect. Tinea corporis is a fungus infection of the skin on the body (corporis is the Latin word for body). If you have this infection, you may see small, red spots that grow into large rings almost anywhere on your arms, legs or chest.
Tinea pedis is usually called “athlete's foot.” (Pedis is a Latin word for foot.) The moist skin between your toes is a perfect place for a fungus to grow. The skin can become itchy and red, with a white, wet surface. The infection may spread to the toenails (this is called tinea unguium—unguium comes from the Latin word for nail). Here it causes the toenails to become thick and crumbly. It can also spread to your hands and fingernails.
When a fungus grows in the moist, warm area of the groin, the rash is called tinea cruris. (Cruris comes from the Latin for leg.) The common name for this infection is “jock itch.” Tinea cruris often occurs in men, especially if they often wear athletic equipment.
Tinea capitis, which is usually called “ringworm,” causes itchy, red areas, usually on the head (capitis comes from the Latin for head). The hair is destroyed, leaving bald patches. This tinea infection is most common in children.
How do I know if I have a fungus infection?
The best way to know for sure is to ask your doctor. Other skin problems can look just like ringworm but have very different treatments. To help decide what is causing your rash, your doctor may scrape a small amount of the irritated skin onto a glass slide (or clip off a piece of nail or hair) and then examine the skin, nail or hair under a microscope. After doing this, your doctor will usually be able to tell if your skin problem is caused by a fungus.
Sometimes a piece of skin, hair or nail is sent to a laboratory to grow the fungus in a test tube. This is another way the laboratory can tell if your skin problem is caused by a fungus. They can also find out the exact type of fungus. This process takes a while because a fungus grows slowly.
How do I get rid of tinea?
Once your doctor decides that you have a fungus infection, different medicines can be used to get rid of it. You may only need to put a special cream on the rash for a few weeks. This is especially true with jock itch.
It can be harder to get rid of fungus infections on other parts of the body. Sometimes you have to take medicine by mouth. This medicine usually has to be taken for a long time, maybe even for months. Some fungus medicines can have unpleasant effects on the rest of your body, especially if you're also taking other medicines. There are some newer fungus medicines that seem to work better with fewer side effects. You may need to have blood tests to make sure that your body is not having a bad reaction to the fungus medicine. It may take a few months or more to get better. Irritated skin takes time to heal. New hair or nails will have to grow back.
What can I do to prevent tinea infections?
Skin that is kept clean and dry is your best defense. However, you're also less likely to get a tinea infection if you do the following things:
When you're at home, take your shoes off and expose your feet to the air.
Change your socks and underwear every day, especially in warm weather.
Dry your feet carefully (especially between the toes) after using a locker room or public shower.
Avoid walking barefoot in public areas. Instead, wear “flip-flops,” sandals or water shoes.
Try not to wear thick clothing for long periods of time in warm weather.
This makes you sweat more.
Throw away worn-out exercise shoes. Never borrow other people's shoes.
Check your pets for areas of hair loss. Ask your veterinarian to check them too. It's important to check pets carefully, because if you don't find out what is causing your fungus infection, you may get it again, even after treatment.
Can tinea cause serious illness?
A fungus rarely spreads below the surface of the body. Your body usually prevents this. People with weak immune systems, like people with AIDS, may have a hard time getting well from a fungus infection, but they don't usually have problems with ringworm. Tinea infections usually don't leave scars after the fungus is gone. A lot of people don't even know they have a fungus infection and get better without any treatment.