What Causes Genital Herpes?

Dr Kathryn Basford

Medically reviewed by

Dr Kathryn Basford

Last reviewed: 26 Apr 2022

Genital herpes is caused by a type of virus, the herpes simplex virus (HSV). It’s a common sexually transmitted infection (STI) that a person can catch through sexual contact.


The most common symptoms of genital herpes are blisters or herpes sores that develop in the genital area. The blisters can burst and develop into ulcers (deep, painful wounds in the skin). Over time, scabs form over the ulcers and they heal.

The symptoms of genital herpes can be uncomfortable. If you have symptoms of genital herpes, you may want to consider what you can do to treat them. In this guide we’ll go through what causes genital herpes outbreaks, the symptoms and possible treatments.

What is genital herpes?

Genital herpes is an infection caused by the herpes simplex virus (HSV). This is the same virus that causes cold sores. There are 2 types of HSV:

  • HSV-1 (herpes simplex virus type 1) is the most common cause of cold sores, but can also cause genital herpes
  • HSV-2 (herpes simplex virus type 2) causes genital herpes, but can also cause cold sores

Genital herpes is a sexually transmitted infection and is most commonly spread through skin to skin contact during sex. This includes vaginal sex, anal sex and oral sex. It can also be spread by sharing sex toys with someone who has genital herpes. It is more likely to spread between sexual partners if someone has symptoms of genital herpes such as visible herpes sores.

With genital herpes, the herpes virus enters your body in the genital area. After the first genital herpes infection, the virus remains dormant in the nerves in the genital area. The herpes virus can be reactivated in the future, leading to new outbreaks where symptoms develop again.

If you think you have genital herpes and it’s the first time you’ve had it, you should visit a sexual health clinic. At the clinic, a doctor or nurse will check if your symptoms are due to genital herpes. They may also take a swab from one of the sores or blisters to test for HSV.

What is a genital herpes outbreak?

A genital herpes outbreak is where symptoms develop again, some time after the initial infection. Sometimes this is called a genital herpes flare up. Once you have been infected with the HSV virus, it stays in your body. The HSV virus lies dormant in a nerve in the area where the infection took place. In the future, the HSV virus may reactivate and symptoms can develop again, and this is called an outbreak.

The first outbreak

The first sign of a genital herpes outbreak may be an itching or tingling feeling in your genitals. During a genital herpes outbreak, you may develop blisters again in the same place as the initial infection. They usually appear on one side only. Genital herpes outbreaks do not generally lead to a person feeling unwell. The blisters also tend to heal more quickly than during the first episode of genital herpes. For most people, outbreaks become less frequent and less severe over time.

Some people never experience a genital herpes outbreak. Others may experience 1 or 2 a year for the first few years after infection. Some people experience 6 or more outbreaks in a year. For most people, eventually the outbreaks will stop completely.

What are the symptoms of genital herpes?

For most people the symptoms of genital herpes are mild. Often, genital herpes symptoms are so mild people are not even aware they have genital herpes.

During the initial period of infection, some people may feel unwell with flu-like symptoms. You may experience mild fever, aches and pains. Symptoms may develop between 2 and 14 days after exposure. Sometimes symptoms do not develop until months or even years after exposure to an infected person with the HSV virus.

The most common symptom of genital herpes is small blisters that appear around the genitals and anus (rectum). The first thing you may notice is a tingling feeling in the area. Painful blisters then develop which may be red and feel sore. You may also feel burning, itching or soreness around the genitals. You may have just 1 blister or you may have several.

After a few days, the blisters can lose their skin and turn into ulcers. This can be uncomfortable and painful. The blisters usually heal in 5 to 10 days. Some women may also notice unusual vaginal discharge, find it painful to pee, or feel pain in the vagina or vulva area.

Factors that may trigger herpes outbreaks

There are lots of different factors that are thought to trigger genital herpes outbreaks, or genital herpes flare ups.

If you have several outbreaks of genital herpes, you may start to recognise factors that can trigger an outbreak. You may find it helpful to keep a note of things that happened just before a genital herpes outbreak. This can help you identify factors or events that may make a genital herpes outbreak more likely. Sometimes though, there may not be any clear trigger for a genital herpes outbreak.

Sexual intercourse

Sexual intercourse may trigger a genital herpes outbreak due to friction in the genital area. If you are currently experiencing a genital herpes outbreak, or have the early signs of an outbreak, you should avoid sex. When you start having sex again, you may find it more comfortable to use a lubricant. Using condoms reduces the risk of catching or spreading genital herpes, although it does not remove the risk completely.

The common cold

Some people have reported the common cold as a trigger for cold sores, which are also caused by the herpes simplex virus. The common cold is not proven to be a trigger for genital herpes, although outbreaks may be more likely if you’re feeling unwell and run down.


Exposure to UV light is thought to be a potential trigger for herpes outbreaks. This includes UV light from sunbeds and from sunbathing. This is more likely for cold sores rather than genital herpes though, as the genital area is less likely to be exposed to UV light.


It’s thought that hormonal changes can trigger outbreaks of genital herpes. Some women find that they experience outbreaks at certain points in their menstrual cycle, particularly around their period. Outbreaks can also happen during pregnancy. If you experience an outbreak during pregnancy, speak to your doctor or midwife for advice.

Weakened immune system

If you have a weakened immune system, you may experience genital herpes outbreaks more frequently. Your immune system may be weakened because of treatment such as chemotherapy or an illness such as HIV. Speak to your doctor for advice about how you can manage genital herpes outbreaks if you have a weakened immune system.

Illness, stress or trauma

Stress can affect your immune system, and may act as a trigger for outbreaks of genital herpes. Stress can take lots of different forms. Illness and trauma are another form of stress on the body that can also lead to outbreaks.

How to manage genital herpes symptoms

There are some other things you can do to help manage the symptoms of genital herpes:

  • wash the area with blisters in plain or salty water
  • avoid scented soaps or bubble baths as they can irritate the blisters
  • wrap an ice pack in a cloth or flannel and apply to the affected area (do not apply ice directly to the skin)
  • avoid sex until any sores have cleared up
  • avoid tight fitting clothes against the affected area
  • if you have an outbreak that is causing pain, you can take pain relief such as paracetamol

If you’re finding it painful to pee (pass urine) you can try the following:

  • pour cool, running water over the affected area when you pee
  • apply vaseline to blisters or ulcers before you pee
  • use 5% lidocaine gel (an anaesthetic) on the affected area to soothe any pain
  • make sure you drink plenty of water

How to treat genital herpes

There are a number of treatment options if you have genital herpes. Antiviral medicines are used to treat the symptoms of a genital herpes outbreak. These medicines do not get rid of the virus from your body, but can help make outbreaks less severe and last for a shorter time. Treatments for genital herpes are usually most effective if you take them as soon as symptoms of a genital herpes outbreak appear.

There are 3 different antiviral medications available from Asda Online Doctor to treat genital herpes: aciclovir, valaciclovir, and famciclovir.


If it’s the first time you’ve had symptoms of genital herpes, you will need to take it 3 times a day for up to 10 days. For further outbreaks, you will need to take it 3 times a day for 5 days.


Valciclovir contains the active ingredient valaciclovir hydrochloride. Your body then converts it to aciclovir. You will need to take valciclovir 2 times a day for 5 days to treat genital herpes.


Famciclovir contains a different active ingredient but works in a similar way to aciclovir and valciclovir. To treat an outbreak of genital herpes, you will need to take 2 tablets in the morning and 2 tablets in the evening for one day only.

If you experience more than 6 genital herpes outbreaks a year, you may be able to take an antiviral medication to reduce the chance of further outbreaks. For example, you may be able to take aciclovir 2 times a day for 6 to 12 months. Fill out an online form with Asda Online Doctor or speak to your doctor for advice.

Frequently asked questions

How common is genital herpes?

Genital herpes is very common. It’s estimated that as many as 7 out of 10 people in the UK will have caught at least one type of HSV by the time they are 25. Most people with HSV have no symptoms at all, or very mild symptoms that do not lead them to seeking any genital herpes treatment or a diagnosis.

Medically reviewed by:
Dr Kathryn Basford

Dr Kathryn Basford is a qualified GP who works as a GP in London, as well as with ZAVA. She graduated from the University of Manchester and completed her GP training through Whipps Cross Hospital in London.

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Article created: 26 Apr 2022

Last reviewed: 26 Apr 2022

(Reviews are for ZAVA UK)

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