Flat warts are smooth, flat-topped, flesh- or brownish-yellow-colored bumps the size of a pinhead. They’re commonly found on the face, back of the hands, or legs, and tend to appear in large numbers. Flat warts are also called juvenile warts because they’re most commonly found in children and young adults. The warts are caused by a virus that’s contagious, but benign, and are usually are not painful.

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Flat warts are smaller than other warts and, unlike other warts, smooth on top. They are very slightly raised, and sometimes hardly noticeable. Flat warts can be round or oval in shape, and are usually between 1-3 millimeters in diameter. Their color ranges from yellowish brown to pinkish to flesh-colored. They can grow in groups of 20 to 200 warts.

Flat warts often appear around a scratch or break in your skin. Men may get them in the beard area from shaving nicks, while women may have them on their legs for the same reason.

All warts are caused by human papillomavirus (HPV), which has more than 100 different types. Flat warts are caused by HPV types 3, 10, 28, and 49. These strains are benign, unlike genital HPV, which can lead to cervical cancer in women.

What causes flat warts? »

HPV is contagious and passed from person to person by touching a wart or using a towel or other personal object that’s been in contact with a wart. The virus enters through a cut or scratch on your skin. You can also spread it from one part of your body to another.

Non-genital warts occur in 7 to 10 percent of the population. Most of the cases occur in young people between the ages of 12 and 16. Warts are among the three most common skin ailments treated, and occur equally in males and females.

Children are most likely to get warts because they often have cuts or scratches on their skin and can be in close contact with many other children. Young people who are beginning to shave are also at increased risk because of razor cuts to the face, neck, or legs.

Teens and others with acne or pimples may touch their face more and scratch or pick at their skin, which can provide an entry point for HPV.

People with a weakened immune system due to chronic diseases, chemotherapy, radiation therapy, drugs, or other factors are at higher risk for HPV.

Poor hygiene can also increase your risk for warts.

If you have bumps on your skin and don’t know what they are, you may want to see your doctor. Usually a doctor can diagnose flat warts by their appearance.

In some cases, your doctor may not be able to diagnose your warts by appearance alone. If this is the case, your doctor may want to do a biopsy of the spots or refer you to a dermatologist.

You should also see a doctor if the flat warts grow larger, change color, or bleed.

Flat warts usually disappear on their own and require no treatment. You may want to receive treatment, however, to speed up your recovery time.

Flat warts often occur on the face or hands, so the harsher treatments used for other types of warts are often ruled out because they may leave scars.

If you decide to treat your flat warts, your doctor may prescribe a topical cream. These creams are irritants and cause the skin to peel, which removes the warts. Prescriptive creams may include:

  • retinoic acid 0.05 percent cream, known as tretinoin (AVITA, Refissa, Retin-A, Tretin-X)
  • Imiquimod 5 percent cream (Aldara, Zyclara)
  • Topical 5-fluorouracil (Carac, Efudex, Fluoroplex, Tolak), 1 percent or 5 percent cream

Your doctor may also suggest 5 percent benzoyl-peroxide (Del Aqua, NeoBenz Micro, Clearskin, EFFACLAR), which is available over the counter.

There are many home remedies for individual wart removal, though most of them have not been studied in a controlled trial.

Because flat warts often occur in large numbers and on the face, it's a good idea to check with your doctor before using a home remedy that might burn your skin or leave a scar. Keep in mind that most of the popular home remedies are meant for treating individual warts, not groups of flat warts.

It’s generally safe to try over-the-counter wart removal medication that contains salicylic acid, but if the wart doesn’t go away with home treatment, you should see your doctor or a dermatologist.

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Flat warts usually disappear on their own. This may take a month or two, or up to two years. Your general health, the type of wart, and the area the warts cover all contribute to how fast the warts may clear up.

In general, 23 percent of warts will disappear within two months, 30 percent within three months, and up to 78 percent within two years.

In most cases, flat warts disappear on their own without complications. Warts can spread and they can also return.

Boosting your immune system can help your health overall, and may assist in speeding up your recovery from flat warts. Keep your immune system healthy by eating right, exercising, and getting adequate sleep.

Warts are caused by an infectious virus, and they are spread by touch. To prevent the spread of the HPV virus that causes flat warts:

  • Don't rub, pick, or scratch your warts.
  • Wash your hands after touching or treating your warts.
  • Don't touch other people's warts.
  • Don't share towels or other personal items.
  • Keep your children's toys clean if they have warts or play with others who have warts.
  • Keep your skin clean and dry.
  • Wear flip-flops or shower shoes in public pool areas or locker rooms.

You may not always be able to prevent warts, but following the above steps can help reduce your risk.