oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
Verrucae or plantar warts are hyperkeratotic lesions found particularly over the pressure areas of the feet (heel and ball). They are usually self-limiting but may be treated if symptomatic.
- Half will disappear within one year.
- Two thirds disappear after two years.
- The remaining one third is more resistant and persistent.
They are caused by the human papillomavirus (types 1 and 2 mainly but also 4). They affect epithelial cells causing small rough papules. Replication of the virus within the epithelial cells causes a proliferative reaction and formation of plaque or papule. Incubation is very variable, ranging from one month up to two years.
- They are spread by person-to-person contact.
- Use of communal showers is associated with higher rates of plantar warts.
- Infection is more likely if the skin is macerated.
- Scratching, nail-biting, finger-sucking and shaving all encourage auto-inoculation of viral warts.
- They should not be used as a reason to stop children swimming, as learning to swim is important in the National Curriculum and helps to prevent death from drowning.
- They may be covered (with waterproof plasters or socks) when swimming but this can stigmatise children and there is no evidence that these measures prevent spread.
Data are limited but:
- Most people get them at some time in their lives.
- They appear to affect women marginally more than men.
- They are more common with peak incidence in children and teenagers (affect about 4-5%).
- They are uncommon in infants.
- They are more common particularly on the hands in eczema and with certain occupations (butchers, abattoir workers, engineers, office workers).
- They may cause pain, particularly with walking.
- Occasionally leg or back pain may result from altered posture or gait disturbance.
- They may be found in other family members.
- They are more common in:
- Firm, hyperkeratotic lesions.
- May have minor pinpoint petechiae centrally within the lesions.
- Usually found over pressure areas.
- Flat because of pressure.
- May fuse with surrounding warts (mosaic warts).
- May occasionally be difficult to differentiate from other conditions (see 'Differential diagnosis', below).
Diagnosis is made by examination and observation of typical features:
- Common warts are common on the knuckles, knees and fingers. They are firm and raised with a rough, cauliflower-like surface.
- Plane warts are round, flat-topped and often yellow in colour. They are common on the dorsal surface of the hands.
- Filiform warts are long and slender. They are common on the face and neck.
- Plantar warts or verrucae grow on the soles of the feet. They may be painful. They often have black dots within them.
- Mosaic warts occur when palmar or plantar warts join up to form large plaques on the hands and feet.
- Corns: these are inflamed and painful. Paring corns reveals pearly sections of keratin.
- Calluses: these are thick and painless patches of hard skin.
- Black heel: patches of hard skin with ruptured capillaries.
- Verrucous squamous cell carcinoma: this should be considered if long-standing. They invade the dermis but are slow-growing and rarely metastasise.
Other conditions that may need to be considered include:
- Acquired digital fibrokeratoma
- Actinic keratosis
- Arsenical keratosis
- Cutaneous horn
- Lichen nitidus
- Lichen planus
- Molluscum contagiosum
- Prurigo nodularis
- Seborrhoeic keratosis
None are usually required or appropriate. Distinguishing them from corns may require paring of the keratin, as above. Blood tests to check for causes of immunodeficiency may be required in unusually widespread or resistant cases.
Usually none. However, consider drugs and diseases affecting particularly cellular immunity.
- Education about the natural history.
- Usually no treatment if they are not painful.
- They are more likely to want or need treatment:
- If they are painful.
- In the immunosuppressed.
- In resistant cases (present for two years or more).
- Patient choice in full knowledge of natural history.
- Choices of treatment include:
- Salicylic acid preparations:
- Several brands are available over-the-counter.
- Combined with podophyllum resin.
- Formaldehyde and glutaraldehyde preparations - unpleasant and used less often.
- Cryotherapy - usually 2 to 4 treatments using a 1-minute freeze/thaw cycle after paring away excess keratin four weeks apart. The freeze-thaw cycle involves freezing until the skin goes white (usually for 5-30 seconds), waiting for the normal colour to return and then repeating the cycle.
- Rarely used methods include surgical excision, curettage, 5-fluorouracil, interferon, photodynamic therapy and bleomycin injection.
- Salicylic acid preparations:
A recent study suggested that salicylic acid and cryotherapy were equally effective. Since salicylic acid is cheaper, this makes it the more cost-effective option. Another study found that nurse-administered cryotherapy was more cost-effective than GP-administered cryotherapy.
One study reported successful treatment of resistant verrucae with adapalene.
Some studies support the use of psychotherapy with adjunctive hypnosis.
Secondary care referral may be necessary for multiple verrucae in immunocompromised patients. Diabetic patients with verrucae should be referred to a diabetic foot clinic.
- Secondary to treatment:
- Scars and keloid formation.
- Malignant change: extremely rare, especially with normal immunity. Whilst it rarely occurs, be aware of the possibility in patients who are immunocompromised (for example, transplant patients).
It should be borne in mind that:
- Treatment failure is common
- Verrucae may be impossible to get rid of in the immunocompromised patient.
- Two thirds will disappear after two years without treatment.
- 90% of warts present at age 11 years, will be gone by age 16 years.
There is no evidence that using verruca socks prevents spread and the possible stigmatising effect of wearing such socks suggests use should be discouraged. Suggestions for reducing spread include:
- Cover the verruca with a waterproof plaster when swimming.
- Wear flip-flops in communal areas and showers.
- Avoid sharing shoes, socks or towels.
- Limit auto-inoculation by avoiding trauma (scratching and biting), keeping feet dry and changing socks daily.
Further reading & references
- Leung L; Recalcitrant nongenital warts. Aust Fam Physician. 2011 Jan-Feb;40(1-2):40-2.
- Shenefelt P, Nongenital Warts, Medscape, Jun 2011
- Gearhart PA et al, Human Papillomavirus, Medscape, Jun 2012
- Warts and verrucae; NICE CKS, June 2009
- Bristow I et al; Dermatological Nursing, 2009;8(3):10-14.
- Brenner RA, Taneja GS, Haynie DL, et al; Association between swimming lessons and drowning in childhood: a case-control Arch Pediatr Adolesc Med. 2009 Mar;163(3):203-10.
- Vaile L, Finlay F, Sharma S; Should verrucas be covered while swimming? Arch Dis Child. 2003 Mar;88(3):236-7.
- Bridger P et al, Minor surgery in primary care - warts and all, Bandolier, 2004
- Micali G, Dall'Oglio F, Nasca MR, et al; Management of cutaneous warts: an evidence-based approach. Am J Clin Dermatol. 2004;5(5):311-7.
- Cockayne S, Hewitt C, Hicks K, et al; Cryotherapy versus salicylic acid for the treatment of plantar warts (verrucae): BMJ. 2011 Jun 7;342:d3271. doi: 10.1136/bmj.d3271.
- Keogh-Brown MR, Fordham RJ, Thomas KS, et al; To freeze or not to freeze: a cost-effectiveness analysis of wart treatment. Br J Dermatol. 2007 Feb 26;.
- Gupta R; Plantar warts treated with topical adapalene. Indian J Dermatol. 2011 Sep-Oct;56(5):513-4.
- Phoenix SL; Psychotherapeutic intervention for numerous and large viral warts with adjunctive hypnosis: a case study. Am J Clin Hypn. 2007 Jan;49(3):211-8.
- Spanos NP, Williams V, Gwynn MI; Effects of hypnotic, placebo, and salicylic acid treatments on wart regression. Psychosom Med. 1990 Jan-Feb;52(1):109-14.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr Richard Draper
Dr Laurence Knott
Dr John Cox