Your skin is your body's largest organ. It has many different functions, including covering and protecting your body. It helps keep germs out. But sometimes the germs can cause a skin infection. It often happens when the germs enter your body through a break, cut, or wound on your skin. Other skin infections can happen in places where the skin rubs together, especially if the area is moist. Infections can also happen when you have a poor blood supply to an area of your body or if your immune system is weakened because of another disease or a medical treatment.

Some skin infections cover a small area on the top of your skin. Other infections can go deep into your skin or spread to a larger area.

Skin infections are caused by different kinds of germs. For example,:

• Bacteria cause cellulitis, impetigo, and staphylococcal (staph) infections
• Viruses cause shingles, warts, and herpes simplex
• Fungi cause athlete's foot and yeast infections
• Parasites cause body lice, head lice, and scabies

You are more likely to get a skin infection if you:

• Have poor circulation
• Have diabetes
• Are older
• Have an immune system disease, such as HIV
• Have a weakened immune system because of chemotherapy or other medicines that suppress your immune system
• Have to stay in one position for a long time, such as if you are sick and have to stay in bed for a long time or you are paralyzed
• Are malnourished
• Have excessive skinfolds, which can happen if you have obesity

The symptoms depend on the type of infection. Some symptoms that are common to many skin infections include rashes, swelling, redness, pain, pus, and itching.

To diagnose a skin infection, your health care provider will do a physical exam and ask about your symptoms. You may have lab tests, such as a skin culture. This is a test to identify what type of infection you have, using a sample from your skin. Your provider may take the sample by swabbing or scraping your skin or removing a small piece of skin (biopsy). Sometimes providers use other tests, such as blood tests.

The treatment depends on the type of infection and how serious it is. Some infections will go away on their own. When you do need treatment, it may include a cream or lotion to put on the skin. Other possible treatments include medicines and a procedure to drain pus.