Herpes is passed on only when it is active on the skin. There is a risk that the virus may be active even though there are no noticeable symptoms, such as blisters or sores. In one study, 70% of transmissions occurred when the person had no symptoms.

For herpes to move from one person to another, one person must have herpes and the other person must be susceptible (not have that type of herpes). Further, these individuals must engage in contact (usually sexual contact) during a period when the virus is active on the skin or mucous membrane. When the virus is active, some people may develop symptoms, such as blisters or sores, while others may have no visible symptoms.

That's why it's important to take precautions to reduce the risk of transmission even when the person with herpes does not have sores or other noticeable symptoms. If you have genital herpes, tell your sexual partner(s) that you have the condition before you have sex, and inform your partner(s) of things you can do to reduce the risk of transmission. These include avoiding sex when sores are present and practicing safer sex at all times, even when sores are not present. Safer sex practices include using condoms for vaginal or anal sex, and dental dams (a flat piece of latex or a latex condom cut lengthwise) for oral sex. Condoms and dental dams can help reduce the risk of herpes transmission, but they do not provide complete protection because they do not always cover all of the infected skin. Your doctor may also recommend using an antiviral medication called valacyclovir that can be used to reduce the risk of transmission. The use of this type of therapy is not for everyone - your doctor can determine if it's right for you. This type of therapy should also be used in combination with safer sex.

Anywhere herpes is active is a place to avoid having contact. If it is in the mouth, then avoid kissing, oral sex, and so on. If on the finger, keep your hand to yourself while your infection is active. If it is on the genitals, avoid genital contact during active infection. You need not avoid kissing if you have active genital herpes unless you have active sores on your mouth, just as people with cold sores on the mouth needn't avoid genital sex - just putting mouth-to-skin. In other words, active herpes is a time to avoid contact with affected areas, but not a time to avoid contact altogether. In fact, it is a time for creative contact. Learn to have contact while avoiding the area of skin actively affected with herpes. This is critical. Total abstinence is okay for a while, but it leads to changes in self-image that are not necessary or useful. However, remember that you can transmit herpes from affected areas to unaffected areas on your own or your partner's body. So be sure to avoid contact with affected areas, and wash your hands after touching affected areas.

Stephen Sacks, MD, FRCPC, with revisions by the MediResource clinical team