Warts can develop on various parts of the body and can have different forms. Warts are harmless skin growths that can be very persistent. Children and adolescents often catch warts when playing sports or at the swimming pool. Warts are caused by a virus.

At a glance

  • Warts are benign (non-cancerous) skin growths.
  • They are usually harmless and disappear on their own within a number of weeks or months.
  • Warts can occur on various parts of the body and can have different forms.
  • Warts are caused by a virus, are contagious, and are very common.
  • Warts can occur at any age, but most commonly affect children and adolescents.
  • Various treatments are available, which can help speed up the healing of warts.

Note: The information in this article cannot and should not replace a medical consultation and must not be used for self-diagnosis or treatment.

Warts: man sitting on a treatment chair in a medical practice and stretching out one leg towards the camera. A young woman wearing a white coat, mask and surgical gloves is holding one of the man’s feet tight and applying nitrogen to a site.

What are warts?

Warts are benign (non-cancerous) skin growths, which can develop on various parts of the body and can have various forms. They are contagious, very common, and caused by a virus. Almost all people will experience warts at some stage of their lives. Warts most commonly affect children and adolescents. However, they can occur at any age.

Warts are usually harmless and disappear on their own within a number of weeks or months. However, they can be a nuisance and can occasionally cause emotional distress due to their frequently unsightly appearance. Various treatments can help speed up the healing of warts. However, treating warts isn’t always effective.

Unlike the viral warts discussed in this article, senile warts, also known as brown warts or wisdom warts (the medical term being seborrheic keratosis) are not contagious. Like viral warts, they are harmless but they are also permanent and usually occur in older people.

What are the symptoms of warts?

Warts do not normally cause pain or discomfort. In some cases, however, they cause itching, skin tightness, or feelings of pressure. Warts on the soles of the feet can also be associated with pain. Some warts have brownish or black dots. These are caused by clotted blood from tiny blood vessels in the skin. 

Warts can appear individually or in clusters. A cluster of warts may cover a larger area of skin. The main types of wart are listed below:

Plantar warts (verrucas)

These mostly occur on the soles of the feet and heels and may be relatively large. As the soles of the feet carry the entire weight of the body, these warts do not grow outwards like other warts, and are instead pushed inwards into the feet due to standing and walking.

Common warts

These skin bumps range from the size of a pinhead to the size of a pea. They harden, making them feel rough and scaly. Common warts frequently occur on the fingers, around the edges of the nails, and on the feet.

Flat warts

These are small warts that are only slightly raised. They often have a diameter of just a few millimeters and are often light brownish in color. Flat warts most commonly occur on the face, especially on the forehead and cheeks. However, the underarms and hands are frequently also affected.

Mosaic warts

These warts are white and roughly the size of a pinhead. Mosaic warts most commonly occur on the balls of the feet or under the toes. In some cases, however, they may spread across the entire underside of the foot. They are flatter than plantar warts and only rarely cause pain during walking.

Facial warts (digitate warts, filiform warts)

These warts consist of thread-like, finger-like, or feathery skin projections. They frequently occur on the face and, as a result, can cause particular distress to the sufferer.

Genital warts (anogenital warts or condylomas)

These appear as small, hard nodules with an irregular surface. These warts only occur in the anogenital area and are sexually transmitted. Their treatment differs from the treatment used for the other wart types listed above.

What causes warts?

Warts are caused by certain viruses belonging to the human papillomavirus (HP virus or HPV) family. There are over 100 different types of these viruses. If they enter the skin through small breaks or fine tears, they cause cell multiplication so that the skin becomes thick and hardened and projects outwards as a wart.

Wart viruses are largely transmitted through direct skin contact, but can also be passed on by sharing certain items, such as towels or shaving equipment. The risk of catching a wart virus is higher if the skin is damp, wet, or broken.

Which factors increase the risk of warts?

Wart viruses multiply in the skin. If an individual has an immune deficiency, the body may be unable to defend itself adequately, and the risk of developing warts is increased. Some people catch warts more frequently because they have more regular contact with wart viruses.

The risk of developing warts is higher among:

  • people who work in the meat processing industry (e.g., in a slaughterhouse or butcher's shop).
  • children and adolescents who frequently use shared showering facilities (e.g., after playing sports or at the swimming pool).
  • those with relatives who have warts.
  • school-age children who are in the same class as someone with warts.
  • people with a weakened immune system, in particular those who have had an organ transplant or who have a serious illness such as cancer or AIDS.
  • people with atopic illnesses such as neurodermatitis. These are allergic conditions in which the sufferer's immune system has an overly sensitive reaction to a otherwise harmless substance in the environment.

How common are warts?

Up to 33% of children and adolescents have warts.

Warts are particularly common among children and adolescents. Studies indicate that up to 33% of children and adolescents have warts. It is also estimated that warts are much less prevalent among adults, at around 3% to 5% of the adult population.

How do warts develop?

For people who are otherwise healthy, warts are almost always harmless. Over time, the body usually builds up immunity against the viruses that cause warts. Warts then disappear on their own at some point. The length of time it takes for the wart to clear up depends not only on the type of virus and wart involved, but also on the person’s general health.

Studies of school-age children and adolescents show that around half of those who develop warts are wart-free after one year. After two years, around 70% are wart-free. Very few studies have been conducted on warts in adults.

Warts may take much longer to clear up if the individual has a weakened immune system.

How can warts be prevented?

People with warts can help prevent others from catching them. In some cases, the same preventive measures can stop warts from spreading over a large area of the skin.

Some measures for preventing the spread of warts to other people are as follows:

  • Cover the wart with a waterproof plaster when swimming.
  • Avoid sharing towels, shoes, gloves, and socks with others.
  • Avoid walking around barefoot in swimming pools and communal showering facilities and changing areas.
  • Don’t touch warts.

The following additional measures may also help someone with warts to prevent them from spreading over their own skin:

  • Don’t scratch or pull at the wart, as this can spread the virus.
  • Always wash hands after touching a wart.
  • Keep feet dry.
  • Change socks daily.
  • Do not use any tools like pumice stones or files if they have previously been used on a wart.

None of these recommendations have been scientifically tested, and so it is unclear how effective they are in practice. Wart viruses are quite contagious, and so completely preventing their spread would be difficult.

How are warts treated?

Warts can be treated by freezing with liquid nitrogen, exfoliating with solutions of salicylic acid.

It is not always essential to treat a wart and, in most cases, they disappear without treatment within a few weeks or months. In some cases, however, they can last for years. Some people find warts unsightly or distressing and resort to treatments to help make them disappear as quickly as possible.

There are two main treatment options for warts:

  • Solutions containing salicylic acid: these solutions are applied to the warts several times a day for a number of weeks. The hardened skin is gradually removed in this way. Most of these solutions are available from pharmacies without a prescription.
  • Freezing (cryotherapy): extremely cold liquid nitrogen is applied to the wart, in most cases by a dermatologist. The cold destroys the cells in the upper layer of the skin. Warts need to be frozen several times at intervals of a week or more. Freezing a wart may cause a brief, piercing pain. After treatment, the skin is often red and swollen. Blistering is also common.

Both of these treatments are generally effective. However, not every wart can be removed in this way. In addition, some of the virus may be left behind, which can subsequently cause a new wart to develop.

Important: Other treatments for warts are also available. However, many of these treatments have not yet been properly tested.

People with certain health risks, such as nerve damage to the feet (due to diabetes, for example), should consult a doctor before starting any treatment for warts. As a precaution, pregnant and breast-feeding women are advised to avoid treating warts.

More detailed information, for example on how to treat warts, is available at gesundheitsinformation.de.

In cooperation with the Institute for Quality and Efficiency in Health Care (Institut für Qualität und Wirtschaftlichkeit im Gesundheitswesen) (IQWiG).

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