Medical Encyclopaedia › Wart (short definition)
In brief: Warts are benign growths of the epidermis caused by infection with human papillomaviruses (HPV). They are very common, especially in children and adolescents, and usually harmless. Many warts disappear by themselves after months to a few years; if they are bothersome or painful, there are several treatment options, although these require patience.
How do warts develop?
Papillomaviruses penetrate the skin through tiny injuries and stimulate the skin cells to grow more. It can take weeks to months before a wart becomes visible. The viruses are transmitted through direct skin contact or indirectly via damp floors, towels and shared objects, for example in swimming pools, showers and changing rooms. Softened, cracked skin and a weakened immune system favour infection. Scratching or shaving can spread warts on one’s own body.
Types
- Common warts (verrucae vulgares): skin-coloured to greyish-brown, rough nodules, often on the hands, fingers and knees.
- Plantar warts (verrucas): on the sole of the foot; they grow inwards due to the pressure of walking and can be painful. Typical are small black dots, which are clotted capillaries.
- Flat warts (verrucae planae): small, flat, often numerous nodules on the face or hands, especially in children and adolescents.
- Filiform warts: narrow, thread-like warts, usually on the face or neck.
- Genital warts (condylomata acuminata): warts in the genital and anal area, caused by other HPV types; they require medical treatment.
Despite their German name, molluscum contagiosum lesions are not true warts but are caused by a poxvirus.
Treatment
Not every wart needs to be treated; waiting is often reasonable, especially in children. If treatment is given, the following are available:
- Keratolytic agents: plasters, solutions or varnishes with salicylic acid, sometimes combined with other active substances, applied daily for several weeks; the softened hard skin is carefully removed regularly.
- Freezing (cryotherapy): in the doctor’s surgery with liquid nitrogen, usually in several sessions; over-the-counter freezing sprays reach lower temperatures.
- Other medical procedures for stubborn warts: removal with a curette, laser, growth-inhibiting or immunostimulating agents.
Studies show moderate effectiveness for salicylic acid; freezing is not superior in every case. Recurrences are common because viruses can remain in the surrounding skin. Genital warts have their own treatments, such as imiquimod cream.
When to see a doctor?
Skin changes whose cause is unclear, that grow quickly, bleed, change colour or hurt should be assessed by a doctor, as should warts on the face, in the genital or anal area and under or around the nails. People with diabetes or circulatory disorders should not treat warts on their feet themselves with acids or devices, as wounds may heal poorly. With a weakened immune system, for example after an organ transplant, numerous or stubborn warts are possible, which should be managed by a specialist. Seborrhoeic keratoses look similar but have a different cause.
Prevention and avoiding transmission
Pool shoes help in swimming pools, saunas and communal showers. Warts should not be scratched open; your own towels, nail files and pumice stones reduce transmission. Covering with a plaster can be useful for contact sports or at the swimming pool. HPV vaccination, recommended by the German Standing Committee on Vaccination (STIKO) for children and adolescents, protects against the HPV types that cause most genital warts when given with a vaccine containing these types; it is not intended against common skin warts and verrucas.
Related terms in the encyclopaedia
HPV, Plantar wart, Molluscum contagiosum, Condylomata acuminata, Salicylic acid, Cryotherapy, Imiquimod, Seborrhoeic keratosis, Corn
Sources
- Kwok CS et al.: Topical treatments for cutaneous warts. Cochrane Database of Systematic Reviews 2012
- Institut für Qualität und Wirtschaftlichkeit im Gesundheitswesen (IQWiG): gesundheitsinformation.de – Warzen
- AWMF-S2k-Leitlinie Anogenitale Warzen (Condylomata acuminata)
- Robert Koch-Institut / Ständige Impfkommission (STIKO): Empfehlungen zur HPV-Impfung
Note: This article is for general information and does not replace advice, diagnosis or treatment from a doctor, dentist or pharmacist. Last updated: October 2026.