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Facts about the skin from DermNet New Zealand Trust. Topic index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Genital Warts

Genital warts are very common. They are caused by a virus, the human papillomavirus (HPV).

Genital warts may occur in the following sites:

Images of genital warts

Normal anatomical structures may be confused with warts. These do not require any treatment.

Transmission of HPV

Visible genital warts and subclinical HPV infection nearly always arise from direct skin to skin contact:

Neonatal infection may arise by passing through an infected birth canal. This can lead to rare complications, such as laryngeal papillomatosis i.e. warts in the throat. Because this complication is unlikely, a caesarean section is rarely indicated simply because a pregnant woman has genital warts.

In small children, genital warts raise the possibility of sexual abuse but in many cases it is due to vertical transmission (see above).

Transmission is common as genital warts often go unnoticed. Subclinical infections can also be infectious.

Often, warts will appear three to six months after infection but latency periods of many months or even years have been reported. Developing genital warts during a long-term relationship does not necessarily imply infidelity.

Visible warts are probably more infectious than subclinical HPV infection. Treating warts seems to decrease the chance of passing on the infection. We cannot tell whether the immune system completely clears the virus from the body, or whether the virus remains hidden but undetectable, capable of re-emerging years later if the immune system weakens. As a result, it is unclear how long someone remains infectious.

The risk of HPV transmission is extremely low if no warts recur a year after successful treatment.


Condoms provide a physical barrier and lower the risk of passing on HPV. They do not, however, prevent all genital skin-to-skin contact.

Use a condom to protect against other STDs, particularly with new sexual partners. For couples in long-term monogamous relationships, the value of condoms is more debatable.

What is the treatment for genital warts?

The primary goal of treatment is to eliminate warts that cause physical or psychological symptoms such as:

The underlying viral infection may or may not persist if the visible warts clear.

If left untreated, warts may resolve, remain unchanged, or increase in size or number.

Most people have a small number of warts that clear with a course of treatment but no one treatment is ideal for everyone.

Options include:

Self-applied treatments

To be successful you must identify and reach the warts, and follow the application instructions carefully.

Treatment at the clinic

Other therapies for genital warts

Genital warts & cancer

The HPV types that cause external visible warts (HPV Types 6 and 11) rarely cause cancer.

Other HPV types (most often Types 16, 18, 31, 33 and 35) are less common in visible warts but are strongly associated with penile and vulvar intra-epithelial neoplasia (pre-cancerous changes) and squamous cell carcinoma (SCC) of the genital area especially cervical cancer and less frequently invasive vulvar cancer and anal cancer.

However, only a very small percentage of those infected will develop genital cancer. This is because HPV infection is only one factor in the process; cigarette smoking and the immune system are also important.

Cervical smears, as recommended in the National Cervical Screening guidelines, detect early abnormalities of the cervix, which can then be treated. If these abnormalities were ignored over a long period, they could progress to cancer.

Human papillomavirus vaccine

Two vaccines are available to prevent HPV infection, Gardasil™ and Cervarix®.

Gardasil is a vaccine that is effective against HPV types 6, 11, 16 and 18; the 4 types of HPV that cause most cases of genital warts, cervical cancer, vulval cancer and anal cancer. HPV also causes some cases of oral and nasopharyngeal cancers. In New Zealand, Gardasil is funded and recommended for 12 year old girls. It can be prescribed for older individuals and males (unfunded).

Cervarix is effective against HPV types 16 and 18. Available in many countries for prevention of cervical cancer, it is not subsidised in New Zealand.

HPV vaccination is most effective when offered at a young age, before the onset of sexual activity. However, girls that are already sexually active may not have been infected with the types of HPV covered by the vaccine and may still benefit from vaccination. It is important to note that women who receive HPV vaccine must continue to participate in cervical screening programmes, as about 30% of cervical cancers will not be prevented by the vaccine.

HPV vaccines are also effective in boys. Although not yet included in New Zealand's routine vaccination programme, vaccination of boys is recommended to reduce transmission of HPV to unvaccinated females. It also reduces the incidence of penile and anal cancers related to HPV infection (including penile intraepithelial carcinoma), as well as some non-genital cancers affecting the oropharynx and larynx.

There has been interest in developing therapeutic HPV vaccines for the treatment of genital warts and cervical cancer in those already infected. However, at present, there is limited evidence that they are effective.

In December 2014, FDA approved Gardasil™9. This is a vaccine approved for use in females ages 9 through 26 and males ages 9 through 15 for the prevention of cervical, vulvar, vaginal and anal cancers caused by HPV types 16, 18, 31, 33, 45, 52 and 58, and for the prevention of genital warts caused by HPV types 6 or 11. It is expected to prevent approximately 90 percent of cervical, vulvar, vaginal and anal cancers.

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Author: Jane Morgan MB ChB MRCP FACSHP
Department of Sexual Health, Health Waikato, Private Bag 3200, Hamilton

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