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Author: Jane Morgan MB ChB MRCP FACSHP, Sexual Health Physician, Hamilton, New Zealand, 2003. Updated by Hon A/Prof Amanda Oakley, September 2015. Revised February 2021
An anogenital wart is a common superficial skin lesion in the anogenital area caused by specific human papillomavirus (HPV) types. Anogenital warts are also called condyloma acuminatum, genital warts, and venereal warts.
Anogenital warts are an infection caused by specific human papillomavirus types, most commonly HPV types 6 and 11. Warts will usually appear three to six months after infection but they may appear months or even years later. Anogenital warts are usually a sexually transmitted infection (STI).
Human papillomaviruses (HPV) are a large family of species-specific related double-stranded DNA viruses.
As anogenital warts are usually sexually acquired, they are most commonly observed in young adults between the ages of 15 and 30 years. [see Sexually acquired human papillomavirus] They are highly contagious. However, anogenital warts are rare in people who have been vaccinated against the benign HPV types in childhood before beginning sexual activity. Anogenital warts have been reported in a number of studies to be more common in males than females.
Patients who are immunocompromised due to drug-induced immunosuppression or HIV infection are at particular risk of acquiring HPV and developing anogenital warts.
Anogenital warts can also affect infants and young children. The virus may be acquired during birth or from the hands of carers.
Visible anogenital warts and subclinical HPV infection nearly always arise from direct skin to skin contact.
An anogenital wart is a flesh coloured papule with a folded irregular surface a few millimetres in diameter. Warts may join together to form plaques up to several centimetres across. A linear pattern may be seen if the virus has been inoculated along a scratch or tear in the skin. Symptoms associated with anogenital warts can include:
HPV infection may occur in the following anogenital sites:
The same HPV types can also be found in lesions around the lips, the oral mucosa or conjunctiva. [see Squamous cell papilloma]
Anogenital warts are contagious and spread particularly to sexual partners.
Anogenital warts can enlarge and multiply during pregnancy which may then interfere with vaginal delivery. HPV can be transmitted to the baby resulting in recurrent respiratory papillomatosis in the infant.
Anogenital warts can impact psychosexual functioning and quality of life. [see Psychosocial factors in dermatology]
Anogenital warts are usually diagnosed clinically.
In some circumstances, researchers and clinicians may wish to confirm the presence or absence of HPV. One commercially available qualitative test for HPV is the COBAS 4800 Human Papillomavirus (HrHPV) Test, which evaluates 14 high-risk (HR oncogenic) HPV types.
Normal anatomical structures may be confused with warts. These include:
Seborrhoeic keratoses are often observed in the anogenital area of older adults.
Anogenital squamous cell carcinoma is an important differential diagnosis to consider as the high-risk and low-risk HPV types are both STIs and can be transmitted together.
HPV vaccination is most effective when offered at a young age, before the onset of sexual activity. However, girls who are already sexually active may not have been infected with the types of HPV covered by the vaccine and may still benefit from vaccination. Women who receive a HPV vaccine should continue to participate in cervical screening programmes.
HPV vaccines are also effective in boys. Vaccination of boys is recommended to reduce transmission of HPV to unvaccinated females. It also reduces the incidence of cancers in males related to HPV infection.
Transmission of anogenital warts to a new sexual partner can be reduced but not completely prevented by using condoms. Condoms do not prevent all genital skin-to-skin contact, but they also protect against other sexually transmitted infections.
To be successful the patient must identify and reach the warts, and follow the application instructions carefully. Available treatments include:
Anogenital warts can resolve spontaneously or in response to treatment. Despite apparent resolution of anogenital warts, the virus can persist in a latent or subclinical form. Recurrence is therefore very common, particularly in males.
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