This site is intended for health professionals only

Warts: should they just be left alone?

Siobhan Hicks
Nurse Practitioner in Primary Health Care
Tower Hamlets

Warts are caused by benign infection of the epidermis with human papillomavirus (HPV),(1) of which there are 80 genotypes that each produce different types of wart. Many types of HPV have an affinity for the skin and produce common warts (verruca vulgaris) and plantar or foot warts (verruca plantaris). Table 1 lists other types of warts. Common warts on the hands and plantar warts are usually due to HPV 1, 2, and 4.(2)


Immunosuppressed individuals are more susceptible to viral warts than others. Children with atopic dermatitis may also have more extensive and persistent warts due to both their decreased immune resistance to viruses and their use of potent topical steroids.(2)
The virus usually enters the skin after direct contact with recently shed viruses, kept alive in warm, moist environments, or by direct contact with an infected person. The virus can be present in the skin before or after obvious clinical infection, and the incubation period varies from one to 24 months. The infectious period is presumed to be as long as the wart is present.(3) The entry site is often an area of recent injury, or if skin is macerated and in contact with roughened surfaces, such as in swimming pools and communal showers.(4)
Warts of the skin can occur at any age.(5) Peak ­incidence occurs at 12-16 years of age,(6) and declines at age 20. Cutaneous warts are common; the incidence in children and young adults is estimated at 10%.(7)

The diagnosis is usually based on clinical examination and characteristic appearance. Common warts are rough, scaly, pink or skin-coloured papules (cauliflower lesions). They occur as single or grouped papules and are most commonly found on the hands and fingers, as well as elbows and feet, but can occur anywhere on the body. In children under 12 years they are common on the knees.(7) Periungual warts may be associated with nail biting.
Plantar warts may be solitary or scattered over the sole of the foot. Their typical appearance is a small area of thickened skin, which when pared away reveals numerous small black dots produced by thrombosed capillaries. Plantar warts are frequently painful. They must be distinguished from calluses and corns, which develop over bony prominences.(8)

Prognosis and complications
Two-thirds of warts disappear within two years,(9)with the average duration for plantar warts being less than one year; 30-50% disappear over a six-month period.(1) Warts may be impossible to eradicate in immunosuppressed people;(5) malignant change is extremely rare but may need to be considered in immunosuppressed patients and the elderly.

A policy of no treatment is generally recommended; however, common warts are unsightly, and treatment may be requested for cosmetic reasons.
Recent data suggest that children with plantar warts should not be barred from swimming;(3) however, some pools or schools insist on plastic verruca socks or waterproof plasters.
The main problem with plantar warts is pressure, which can frequently be relieved by paring the wart regularly. Current recommended treatment based on a recent Cochrane review found that topical treatments containing salicylic acid were effective and safe;(11) minor skin irritation occurs occasionally, but there are no major adverse effects. This should be continued for three months before considering an alternative. There is no current evidence to guide the best choice of product, but note that topical salicylic acid should not be used on the face because of the risk of severe irritation and possible scarring.
The wart should be soaked in warm water five minutes before application of the product, debriding gently with a nail file 1-2 times a week to remove hard skin. Collodion-based salicylic acid products form a film over the wart, so a plaster is not needed to keep the active treatment on the wart area. Occlusion improves the clearance rates of plantar warts,(12) and a recent trial found that occlusion with duct tape was more effective for the treatment of common warts than cryotherapy.(13)
Cryotherapy with liquid nitrogen can be used on warts that do not respond to topical treatment. However, there is no clear evidence to support this approach, and it may be of only equal value to topical salicylic acid.(11,14) Cryotherapy is painful and should not be inflicted on small children. Risks include blistering, pigmentary disturbance, scarring, damage to nail growth, and, rarely, damage to underlying nerves and tendons. Biopsy may have to be performed before cryotherapy if the diagnosis is unclear. It is common for blistering/inflammation and haematoma to occur postprocedure.

Lauren and her mum were happy with the diagnosis; however, there is a confusing array of advice and treatment options to contend with for health professionals and the general public. It is important to offer reassurance and/or treatment to eliminate the verruca with minimal side-effects and disruption to the patient's life.



  1. Sterling JC, et al. Br J Dermatol 2001;144(1):4-11.
  2. Verbov J. Arch Dis Child 1999;80:97-9.
  3. Public Health Laboratory Service. Guidelines on the management of communicable diseases in schools and nurseries: warts and verrucas. London: PHLS; 2002.
  4. eMedicine Health. Consumer health information. Available at URL:
  5. Lowy DR, Androphy EA. Warts. In: Fradberg IM, Eisen AZ, Wolff K, et al, editors. Fitzpatrick's dermatology in general medicine. New York: McGraw-Hill; 1999.
  6. Cobb MW. J Am Acad Dermatol 1990;22:547-66.
  7. Sterling JC, Kurtz JB. Viral ­infections. In: Champion RH, Burton JL, Burns DA, Breathnach SM, editors. Textbook of dermatology. 6th ed. Oxford: Blackwell Science; 1998.p. 995-1096.
  8. Graham-Brown R, Burns T. Lecture notes on dermatology. Oxford: Blackwell Science; 2002.
  9. Massing AM, Epstein WL. Arch Dermatol 1963;87:306-10.
  10. Allen AL, Seigfried EC. Adolesc Med 2001;12(2):229-42.
  11. Gibbs S, et al. BMJ 2002;325 (7362):461-8.
  12. Veien NK, et al. J Dermatol Treat 1991;2(2):59-61.
  13. Focht DR, et al. Arch Paediatr Adolesc Med 2002;156:971-74.
  14. Bigby M, et al. Clin Evid 2002;8:1731-44.

Patient UK
Information leaflets on health and disease