What Causes Herpes?
Medically reviewed by
Dr Clair GraingerLast reviewed: 03 Feb 2026
Herpes is a common sexually transmitted infection (STI) caused by the herpes simplex virus (HSV), mainly HSV-1 or HSV-2. It is easily spread by direct skin-to-skin contact, such as kissing or during sex. Once you have been infected with the herpes virus, it remains in your body for life, hiding in nerve cells. The virus can become active again, causing an outbreak that results in sore and painful blisters. Outbreaks of herpes are often triggered by stress, illness, or sunlight exposure, but they can be easily managed.
Here, we explore what causes herpes, how it is spread, what you can do to lower the chance of getting it, and how to manage the symptoms.
What causes herpes?
Herpes is caused by the herpes simplex virus (HSV). It can infect several areas of the body, most commonly your mouth (oral herpes) and genitals (genital herpes). Once you have been infected, the virus remains in your body for life. It usually remains inactive but can become active again, causing outbreaks.
Although herpes is spread through direct skin-to-skin contact, it is not caused by your lifestyle or personal hygiene. In the UK, it is very common, with around 70% of people thought to be infected with HSV by the time they are 25.
There are several types of HSV, but the 2 most common are HSV-1 and HSV-2.
HSV-1 causes
HSV-1 causes oral herpes, also known as cold sores, and, in some cases, genital herpes. It is spread by coming into contact with infected saliva or mouth sores during kissing, sharing items, or during oral sex.
HSV-2 causes
HSV-2 mainly causes genital herpes and is spread through skin-to-skin contact, especially during vaginal, oral, and anal sex or touching sores.
What causes herpes outbreaks?
Genital herpes outbreaks are caused by the virus becoming reactivated in the body. What causes herpes outbreaks in you may be different to someone else, as there are many different triggers. Although the first outbreak is often the most severe, recurrent outbreaks are usually less frequent and shorter lasting.
What triggers herpes?
Some of the common herpes triggers include:
- stress – stress can come in many forms and affect your immune system, triggering herpes outbreaks
- illness – illnesses, like cold and flu, can trigger herpes outbreaks as they impact the immune system, allowing inactive herpes viruses to become active again
- fatigue – like stress and illness, fatigue weakens the immune system, causing herpes outbreaks
- hormonal changes – hormonal changes during the menstrual cycle, pregnancy, and menopause are common herpes triggers
- sun exposure – ultraviolet (UV) light from the sun can weaken the skin's immune system allowing HSV to reactivate and cause an outbreak, especially cold sores
- poor sleep – not getting enough sleep can impact your immune system and cause hormone changes, and research shows people with sleep issues have an increased chance of getting shingles, which is caused by another type of herpes virus called herpes zoster virus
Can you get herpes without having sex?
Yes, you can get herpes without having sex because it is passed on through skin-to-skin contact, like kissing someone who has cold sores, touching an infected area and then touching yourself, or through sharing some personal items, including sex toys.
Other causes of herpes virus include:
| Herpes can be caused by: | Herpes cannot be caused by: |
|---|---|
| ✓ kissing | ✗ sharing toilet seats |
| ✓ touching sores and then touching someone else or another part of your body | ✗ casual touching or hugging |
| ✓ sharing lip balm, drinks, utensils | ✗ sharing towels or bedding |
| ✓ childbirth | ✗ sharing swimming pools or hot tubs |
Is herpes always contagious?
Yes, active herpes is always contagious. Both HSV-1 and HSV-2 are easily spread when there are active sores present on the skin, but they can also be spread when there are no visible signs. This is called asymptomatic shedding.
Herpes is most contagious during an outbreak, when there are visible sores. However, you can pass the virus on from the first tingling or itching sensation you might get that signals an outbreak is coming.
Asymptomatic shedding is when HSV is present on the skin’s surface and can be passed on to other people, but you have no herpes symptoms or sores. When asymptomatic shedding occurs, it can be unpredictable, but it is common after the first infection or after recurrent outbreaks.
How to reduce the risk of getting or spreading herpes
Even though there is no cure for herpes once you have been infected with the virus, there are several things you can do to lower the chance of getting it or passing it on to others. These include things like using barrier methods of contraception, regular STI testing, and taking antiviral medications correctly.
Some of the things you can do to protect yourself against herpes include:
- use condoms every time you have sex
- limit the number of sexual partners you have to reduce the chance of STIs, including genital herpes
- get tested regularly, especially if you have a new sexual partner – you can even test yourself for genital herpes at home if you have new genital lesions
- avoid sex during outbreaks – this is when you or your partner are most likely to pass the virus on, and includes anal, vaginal, or oral sex until all the sores have gone away
- be honest about the fact you have herpes with your sexual partners
- take antiviral medication to help speed up the healing process and stop you passing the infection on to others
Antiviral medication
If you have a genital herpes outbreak, there are several antiviral medications available that can help manage the symptoms.
At Superdrug Online Doctor, we can provide the following antiviral genital herpes treatments:
| Aciclovir | Valaciclovir | Famciclovir | |
|---|---|---|---|
| Form | Tablet you can swallow (oral tablet) | Oral tablet | Oral tablet |
| How it works | Stops HSV growing and spreading | Stops HSV growing and spreading by interfering with its DNA | Stops HSV growing and spreading |
| How to take | 1 x 400mg tablet 3 times a day for 5 to 10 days | 1 x 500mg tablet twice a day for 5 to 10 days | 2 x 500mg tablet 2 times a day for 1 day |
| Effectiveness | Reduces viral shedding by 7 days | Reduces the spread of HSV by up to 75% | Effectively reduces the number of recurrent genital herpes outbreaks compared to a placebo |
Summary
Herpes is a common viral infection, and 70% of people are affected by the time they are 25. There is no cure, but outbreaks can be easily managed with antiviral medication and self-help measures.
If you get an outbreak, our doctors can prescribe genital herpes medication to shorten the duration of symptoms. We can also provide longer-term herpes suppression antiviral treatment to reduce the number of outbreaks you have and the risk of passing the virus on to any sexual partners. And if you are not sure if you have herpes, you can order an at-home genital herpes test kit.
FAQs
What is the main cause of herpes?
Herpes is caused by the herpes simplex virus (HSV). There are many different types of HSV, but HSV-1 commonly causes oral herpes and HSV-2 primarily causes genital herpes.
Can stress alone cause herpes?
No, stress on its own does not cause the initial herpes infection. You will need to be infected with HSV first, but stress is a known trigger for recurrent outbreaks if you already carry the virus. Stress weakens your immune system, which allows HSV to become active and cause blisters and sores.
Can herpes appear years later?
Yes, herpes can cause symptoms years after you were first infected because the virus can remain inactive in your body and become active later on. You can get herpes even if you have only ever had 1 partner. There are many different triggers that can cause an outbreak, including illness, stress, and hormonal changes.
What causes herpes on the lips?
Herpes on the lips is usually caused by HSV-1. This causes cold sores, which can be passed onto other people through kissing, sharing personal items, and oral sex. It’s also possible for cold sores to be caused by HSV-2, because the virus can be passed on during oral sex.
Can herpes cause bruising?
The most common symptoms of herpes are painful, fluid-filled blisters or sores, which can make the surrounding skin red and inflamed. This can sometimes be mistaken for bruising. If you have unexplained bruising, you should contact a doctor for more advice straight away.
What kind of pain can herpes cause?
A herpes outbreak can be painful, especially if it is your first one, and you may get symptoms including:
- tingling
- burning
- itching
- shooting nerve pain
- deep aching in your legs, buttocks, or hips
Some people may also get flu-like symptoms during their first outbreak, which can also include muscle and joint aches. If you have a fever, severe headache, vomiting, are not able to pass urine, or have any lesions that last longer than 3 weeks, you should contact your doctor straight away.
Sources
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- Famciclovir 500mg film-coated tablets, emc [accessed 29 December 2025]
- Genital Herpes, NHS [accessed 29 December 2025]
- Genital herpes: Learn More – How can you prevent the spread of herpes in sexual relationships?, National Library of Medicine [accessed 29 December 2025]
- Shedding Patterns of Genital Herpes Simplex Virus Infections, JAMA [accessed 29 December 2025]
- The Incidence and Risk of Herpes Zoster in Patients With Sleep Disorders, Medicine [accessed 29 December 2025]
- Valaciclovir 500 mg film-coated tablets, emc [accessed 29 December 2025]
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