Genital warts are benign skin tumours caused by members of the human papilloma virus (HPV) family, of which at least 60 different types exist. The wart virus gains entry through the tiny cuts or splits in your skin during skin-to-skin contact - most usually during sex with an infected person.

Most carriers of the wart virus do not have active warts, so lack of visible warts on a sexual partner does not mean they're free from infection. Using male condoms helps to prevent transmission of wart virus but may not give total protection, as they may not cover all affected areas (for example, warts may be present on the scrotum).

What symptoms will you notice?
Wart viruses stimulate overgrowth of skin cells to form warts that can vary from small, multiple, finger-like projections to single, large growths. They can occur anywhere on the male and female genitals and anus.

Once you're infected, the virus lies dormant in cells and the warts may appear from several weeks to 20 months afterwards. Some people are naturally immune and never show signs of infection and, as genital HPV is so common, it is thought that the majority of sexually active people have been exposed to HPV infection at some time. This is because even when warts are treated and disappear, the wart virus can still be found lying dormant in skin cells, so that recurrences and transmission to others are common.

Genital warts occasionally appear in people who have never been sexually active, which suggests that wart virus may be passed on in non-sexual ways (for example, via the fingers) or during non-penetrative sex.

How are genital warts diagnosed?
This relies on seeing the typical warty growths. Sometimes structures such as skin tags or remnants of the hymen may be mistaken for genital warts.

How are genital warts treated?
The latest treatment: Imiquimod. The drug is known as an immune response modifier as it stimulates the body's own immune system to attack the viruses that cause genital warts. Unlike podophyllotoxin, it does not have any anti-viral action. Imiquimod cream is applied three times a week to the wart area before you go to sleep and is then washed off six to ten hours later (i.e. next morning) with mild soap and water. While the cream is in place, you should avoid showering, bathing or sexual contact. Treatment continues until the warts clear or for a maximum of 16 weeks. It is only available on prescription and may be reserved until other, cheaper treatments have failed.

The quickest results: When warts are destroyed by heat under local anaesthetic. This leaves a shallow burn, which heals over the following week to produce instant results. This is usually the best method for treating larger or multiple genital warts. Extensive warts can also be surgically removed under general anaesthetic.

Painting with podophyllotoxin: Those that are soft and non-keratinised are usually painted with a solution or cream containing podophyllotoxin (a cytotoxic substance that literally kills wart-infected cells). Podophyllotoxin can be used as a home-based treatment - you apply the dilute solution or cream twice daily for three days per week over a maximum of five weeks before being re-assessed. Podophyllotoxin and podophyllin must not be used during pregnancy, as they may be absorbed to cause developmental abnormalities.

Trichloro-acetic acid: Some clinics occasionally treat warts with a caustic substance - trichloro-acetic acid (TCA) - on a weekly basis. This strong acid coagulates wart cells and usually works quickly. It can lead to ulceration of surrounding skin so is now less frequently used.

Freezing with liquid nitrogen (cryotherapy): Treats warts by disrupting and killing cells through repeated freezing then thawing. Several sessions are usually needed before the warts disappear.

Genital warts link to cervical cancer
One or two of the sixty plus wart viruses are associated with an increased risk of developing genital cancers, including cervical cancer. The viruses linked with cervical cancer do not seem to cause visible warts. Therefore, women who have had visible warts are no more likely to develop cervical cancer than people without visible warts.

As a result, women with warts do not usually need to have more frequent cervical smears than women without warts, although this used to be recommended. You only need to attend routine smears according to the usual screening programme, although you may be advised to have regular cervical smears if certain changes are found that need to be checked more regularly.

If you're worried you have an STI or want to find out more, check out the symptoms, diagnosis and treatments for:

• Chlamydia
• Genital herpes (HSV)
• Gonorrhoea
• HIV and AIDS
• Pubic lice
• Scabies
• Syphilis
• Trichomonas