Genital herpes is caused by Herpes simplex virus (HSV), either HSV-1 or HSV-2. HSV gains entry to the body through the delicate membranes of the genital tract, mouth, and anus or through tiny abrasions in the skin (initial infection.)
The virus then enters adjacent nerve tissue where it persists but is generally kept under control by immune cells in healthy skin.  However, certain factors, especially trauma to the skin, result in weakening of the skin’s protective immunity and release of virus particles onto the skin surface (recurrent infection).


Many people never have symptoms, either during initial infection or during recurrences.  In some, initial infection can be quite severe with multiple painful ulcers, difficulty passing urine, muscular aches, headache and fever. Recurrences are typically small localised blisters which ulcerate and occur not only on the genitals, but also on the buttocks, thighs and anus. Many recurrences occur with either no symptoms or as only minor itching or irritation.  Nevertheless, infectious virus particles may be shed from the skin during these episodes.


A swab is taken from the ulcer, skin split or itchy spot and sent to a laboratory for virus detection.  This is the most accurate method of diagnosing herpes and also detects whether the infecting virus is HSV-1 or HSV-2.
There are also blood tests available which detect blood antibodies against the different HSV types.  These tests are not terribly accurate and provide too many false positive and false negative results to make them very useful. Because of this, the Melbourne Sexual Health Centre does not routinely test for herpes using a blood test when clients ask for a check up for sexually transmitted infections when they do not have symptoms or signs of herpes.


Both virus types can cause genital herpes but with different outcomes.
HSV-1 is the cause of oral cold sores and genital HSV-1 infection occurs when someone with the cold sore virus (who may or may not have symptoms) performs oral sex on someone who has had no previous exposure to HSV-1.  Initial genital HSV-1 infection may be quite painful, but recurrences and viral shedding without symptoms occur much less frequently than with genital HSV-2 infection. People with genital HSV-1 infection rarely need to use antiviral treatment after the initial episode and rarely transmit the infection to sexual partners.
Genital HSV-2 infection, on the other hand, is associated with frequent symptomatic recurrences as well as atypical and asymptomatic viral shedding episodes and a risk of transmission to sexual partners.  Most people with genital HSV-2 will, at some time, require treatment with antiviral medications for control of recurrences or relief from symptoms.
Initial oral HSV-2 infections are uncommon and almost never recur in healthy people.  Oral cold sores are virtually always caused by HSV-1 infection.  


Antiviral medications (Valtrex®, Famvir®, Zovirax®) help manage the symptoms of herpes. They are very effective and very safe, even when taken for prolonged periods.
Initial HSV infections should be treated for up to 14 days to reduce the severity and duration of the initial episode. 
Mild and infrequent recurrences can be treated with short (e.g. 2-day) courses, i.e. episodic therapy.  Treatment should be started at the first sign of symptoms and, if taken early enough, e.g. at the stage of itching or redness, can sometimes prevent the full development of herpes lesions.
Frequent recurrences can be suppressed by taking a continuous daily dose of as little as 1 tablet daily.  This suppressive therapy also has the advantage of reducing transmission to sexual partners.  
People with herpes frequently switch between episodic and suppressive therapies according to their needs and circumstances. 


Avoiding direct contact with the virus is the only way to prevent infection. Therefore, avoid having sex with someone who has an active genital or oral sore as there is a high risk of transmission at this time. Herpes can, however, be present on the skin without causing any symptoms and be transmitted by someone who has no sores present. Reducing your number of sexual partners and using condoms will reduce the likelihood of coming into contact with herpes.


Studies of couples where one partner has genital HSV-2 show transmission rates of between 5-20% per year, women with no exposure to HSV-1 having the highest risk (20%) and men with previous HSV-1 infection having the lowest risk (5%). Prior HSV-1 infection appears to give some cross-immunity to HSV-2 infection.
People who have acquired their HSV-2 infection within the previous 12-18 months appear to be more infective than those with more longstanding infection.
Most HSV transmissions occur within the first few months of a relationship, so it is recommended that couples consider the following measures for at least 6-12 months:

  • Using condoms consistently will reduce the risk by about 50%.
  • If the partner with herpes takes suppressive antiviral therapy, this will reduce the risk by 50%.
  • If skin trauma is avoided, this will reduce the risk of viral shedding in the partner with herpes and an intact skin barrier will be maintained in the partner at risk. Silicone-based lubricants are recommended, but tend to be available only at sex shops or online.

Some people at risk of herpes ask for a blood test to check their prior HSV exposure.  We advise them that the results may not be accurate enough to truly assess their risk and that they should, whatever the test result shows, practice the simple preventative measures mentioned above.


Neonatal herpes (herpes affecting the newborn) is an uncommon but serious infection. 
The risk of transmission to a newborn is greatest if a woman acquires an initial herpes infection in the last 3 months of pregnancy. In such cases caesarian delivery is always recommended. A man with cold sores should not perform oral sex on his pregnant partner, unless she is known to already have HSV-1 infection.  A man with genital herpes should consider using suppressive antiviral therapy, condoms and a good lubricant throughout his partner’s pregnancy if she is at risk of acquiring his infection.
A woman with recurrent genital herpes has a very low risk of transmission to her newborn. A caesarian delivery would be considered only if visible HSV ulcers are present at the time of her delivery.  Some pregnant women with recurrent herpes choose to take suppressive antiviral therapy during the final few weeks of pregnancy, to prevent recurrences and therefore avoid a caesarian delivery.  This has been shown to be both safe and effective.


People who have just found out that they have genital herpes have many questions.  They should get as much information as they can about herpes, so they can make fully informed decisions about treatment, safe sex and managing further recurrences.

Talking to a counsellor is also an option; this provides time for the individual to explore what having herpes means for them and  to discuss their concerns.

This fact sheet is designed to provide you with information on Herpes (Herpes simplex virus/ HSV). It is not intended to replace the need for a consultation with your doctor. All clients are strongly advised to check with their doctor about any specific questions or concerns they may have. Every effort has been taken to ensure that the information in this pamphlet is correct at the time of printing.
Last Updated August 2013