Factsheet Herpes

Selina Corkery, Published November 2017

Key points

  • Herpes is transmitted by contact with skin where the herpes simplex virus is present. It causes painful blisters on the genital and surrounding areas.
  • Antiviral treatments can reduce the discomfort of an outbreak of herpes.
  • Having the herpes virus makes sexual transmission of HIV more likely.

Herpes is caused by a common virus called herpes simplex virus (HSV). This is a common sexually transmitted infection in the UK.

When you acquire the herpes virus, it stays in skin and nerve cells for life. However, you may not know that you have HSV. Most of the time, the infection does not cause symptoms, but the virus is still present, meaning that it can be passed on to others.

Oral and genital herpes

There are two main types, HSV 1 and 2. HSV 2 is most commonly associated with genital herpes, but both viruses can cause either genital or oral herpes.

Oral herpes causes tingling or painful fluid-filled blisters on the edge of the lip where it meets the skin of the face (‘cold sores’). These can occasionally develop on the nostrils, on the gums or on the roof of the mouth.

Genital herpes involves painful, fluid-filled blisters in the genital or anal areas, sometimes accompanied by fever, headache, muscle ache and a general feeling of being unwell.

Transmission and prevention

The virus can be transmitted from person to person by contact with skin where HSV is present. The virus passes easily through mucous membranes in the mouth, genital areas and anus, so can be passed on by kissing and other sexual contact. It can be passed from one part of the body to another, by touching the blisters or the fluid from them and then touching another part of the body. This can lead to particular problems if the infection is transferred to the eyes.

It is especially easy to get herpes when blisters are present, but it can also be transmitted when sores are not present. People with HIV are more likely to ‘shed’ virus, especially if they have a low CD4 count

It is possible to pass herpes infection on to a baby through vaginal delivery. It is recommended you have a caesarean section if you are pregnant and have an active outbreak of herpes at the time of delivery.

Avoid having sex (oral, anal or vaginal), if you have symptoms or feel them starting. Don’t share sex toys, or cover them with a condom or wash them between uses. Avoid kissing if you or your partner has a cold sore. Avoid touching any affected area; thorough hand-washing will reduce the risk of spreading the infection if you do touch it.

Using a condom for anal, vaginal and oral sex offers a degree of protection from infection with herpes, or from passing on the virus to somebody else.

However, protection isn’t complete as the skin around the genital area may also carry the infection.

Herpes and HIV infection

In a person with HIV who is not taking HIV treatment, herpes may make them more infectious. This is because untreated sexually transmitted infections can increase HIV viral load in genital fluids and because HIV is present in herpes blisters. However, if the person with HIV is taking effective HIV treatment and has an undetectable viral load, they will not pass HIV on. Herpes will not make a difference to this.

HIV-negative people who have herpes blisters are more vulnerable to HIV infection, as the blisters provide a break in the skin through which HIV can enter.


HSV is easiest to detect when the infection is still active, so it is best to seek medical advice as soon as you develop symptoms. It can be diagnosed by examining the affected skin, and by taking a swab of the fluid from a blister. A blood test can detect the virus, but this isn’t routinely used. A routine sexual health check won’t look for herpes unless you let staff know you have symptoms or are concerned.


Many people will not have any symptoms at all. Others will have symptoms within a few days of infection.

An outbreak of herpes involves painful blisters or sores which affect the mouth or genitals. Herpes lesions often start as numbness, tingling or itching. This feeling indicates that the virus is travelling up a nerve to the skin. There it causes small bumps that rapidly develop into small inflamed and fluid-filled blisters. These burst and crust over, typically taking a week to heal in people with healthy immune systems. 

In people who are not on HIV treatment and whose immune system is very weakened, the first attack of genital herpes can be severe and long-lasting and, in some cases, cause serious, systemic illness.

"Herpes is more likely to reproduce in people with weak immune systems."

From time to time, flare-ups can occur. HSV 2 recurs more often than HSV 1. Often, attacks become milder and less frequent as time goes on, usually about two years. In people living with HIV, especially if they have a very low CD4 cell count (under 50), herpes attacks tend to be more frequent, more severe and last longer. Sometimes the lesions can become infected with other bacteria. 

Some people find certain triggers will bring on an outbreak, such as being unwell, tired or stressed, drinking alcohol and smoking, or exposure to the sun or sunbeds.


There is no treatment that can eradicate infection with herpes viruses.

HIV treatment is an important element in reducing frequency of herpes reoccurrences, but has less of an effect on genital shedding.  

There are antiviral treatments that can reduce the discomfort of an outbreak. These reduce the amount of viral replication while you are taking them. The most commonly used treatments are aciclovir, valaciclovir and famciclovir. Antiviral treatments for herpes infection work well in people with HIV when used to treat outbreaks. There is some evidence they work less well to suppress herpes virus shedding in people living with HIV.

The sooner you start treatment, the more effective it is likely to be. Although effective at preventing outbreaks of herpes, once an attack of genital herpes is established antivirals often provide little benefit. It is recommended people with HIV start antiviral treatment for HSV as soon as possible after an outbreak starts.

Antivirals are usually taken in tablet form, up to five times a day for seven to ten days to treat serious attacks of oral herpes and genital or anal herpes. In serious cases, aciclovir can be given intravenously.

Antivirals can be taken as ‘episodic’ treatment, each time you feel the symptoms of the start of an attack (usually tingling and numbness). For many people with HIV, the standard episodic treatment course (of five days) will work well. However, if you have a weakened immune system, you may need a longer course of antivirals. They can also be prescribed as ‘suppressive’ treatment, usually if you have more than six outbreaks a year. If this is the case for you, you may be on treatment for up to a year.

You can reduce the discomfort of an outbreak by taking painkillers or applying a topical anaesthetic, such as lidocaine, and bathing the affected area in salty water. Applying an ice pack or cold wet teabags, may help. Avoid tight clothing and drink plenty of fluids.

This factsheet is due for review in November 2020

Find out more

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.
Community Consensus Statement on Access to HIV Treatment and its Use for Prevention

Together, we can make it happen

We can end HIV soon if people have equal access to HIV drugs as treatment and as PrEP, and have free choice over whether to take them.

Launched today, the Community Consensus Statement is a basic set of principles aimed at making sure that happens.

The Community Consensus Statement is a joint initiative of AVAC, EATG, MSMGF, GNP+, HIV i-Base, the International HIV/AIDS Alliance, ITPC and NAM/aidsmap

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.

NAM’s information is intended to support, rather than replace, consultation with a healthcare professional. Talk to your doctor or another member of your healthcare team for advice tailored to your situation.