Let’s get something straight from the very beginning: Ringworm (tinea corporis) is not, in fact, caused by worms. Instead, it’s a fungal infection of the skin, a rash that takes the form of — you guessed it —concentric rings.

It spreads easily. It’s jarring to see. Sometimes it can be itchy. But ringworm is very treatable, provided you catch it early and get the right medicine.

What is ringworm?

Ringworm is caused by a skin fungus called a dermatophyte. These dermatophytes nest in the outermost layer of skin, known as the epidermis. They like this spot because it’s warm, which helps them grow. Once they get busy multiplying, you see symptoms such as flaking skin, redness and sometimes swelling. The rings usually start small, then spread outward.

You can develop ringworm just about anywhere on your body. But there are some places where it tends to pop up more often. Hands are a common spot. Faces, too, since people touch them so often.

How do you get ringworm?

The infection is mainly caused by human-to-human contact, and kids are especially susceptible, says Phillip Kadaj, MD, an internal medicine specialist with MidMichigan Health, in Midland, Michigan, and an expert with JustAnswer. “As any parent knows, children have a hard time keeping their hands off one another,” Dr. Kadaj says.

Liz Roberts Savasta, who lives in Northport, New York, learned this firsthand. When her twin boys were 3 years old, her son Joshua came home from day care with a case of ringworm. One of the providers had noticed the rash when they were changing his diaper and suggested Savasta get it checked out.

When she did, she was shocked to learn what it was. She didn’t think humans could get ringworm.

Savasta treated her son with ketoconazole cream 2 to 3 times a day for 14 days. Miraculously, the other boy never got the infection. “They’re twins, so there’s no way I’m keeping them apart. But somehow Ethan didn’t get it, which was a huge relief,” she says.

Lucky, too, because human contact isn’t the only way you can get ringworm. You can pick it up from surfaces (including towels, blankets, toys and brushes). And you can get it from animals such as dogs, cats and even cows. Rarely, ringworm can be transmitted through soil.

How do you treat ringworm and keep it from spreading?

The first step is to get an official diagnosis. Many ringworm infections go undiagnosed because people confuse the rashes with other ringlike skin irritations, such as psoriasis, eczema and Lyme disease.

Once your doctor confirms ringworm is the culprit, follow these steps to contain the spread:

  • Keep the area very dry, as dermatophytes grow better in warm, moist environments.
  • Use an over-the-counter treatment such as clotrimazoleketoconazoleor terbinafine. Your pharmacist can help guide you. If the infection won’t go away or is severe, you may need to see your doctor for a prescription antifungal treatment. Keep using the medicine for as long as your doctor instructs, even if the rash heals sooner.
  • Become a clean machine. This is tedious work, but it’s necessary.
  • Wash your hands every time you touch the rash and before you touch anything else.
  • Use 1 towel to dry the affected area after a shower and another for the rest of you. Do not reuse! You’ve got to wash them every time. Same goes for clothes and linens. Otherwise, you could keep reinfecting yourself or others.
  • Regularly disinfect any surfaces or objects that have come into contact with the rash.

Continue this routine until your doctor gives you the all-clear. How long will that be? Anywhere from 2 to 4 weeks in most routine cases, says Dr. Kadaj.

Did you know ringworm is related to athlete’s foot and jock itch? Here’s more about the treatment that can relieve all 3.