Cold sore (herpes simplex virus) 


Cold sores are small blisters on the lips or around the mouth that are caused by the herpes simplex virus  

When to visit your GP

If you have had outbreaks of cold sores before, it's likely that you will know what they are if they return.

You only need to visit your GP if you think you or your child has become infected with the herpes simplex virus for the first time, or if the cold sores have not healed after 7 to 10 days.

Cold sores are small blisters that develop on the lips or around the mouth. They are caused by the herpes simplex virus and usually clear up without treatment within 7 to 10 days.

You will not have any symptoms when you first become infected with the herpes simplex virus. An outbreak of cold sores may happen some time later.

Cold sores often start with a tingling, itching or burning sensation around your mouth. Small fluid-filled sores will then appear, most commonly on the edges of your lower lip.

Read more about the symptoms of cold sores.

What causes cold sores?

The strain of herpes simplex virus usually responsible for cold sores is known as HSV-1.

In rare cases, cold sores can also be caused by the herpes simplex virus type 2 (HSV-2). This can be the result of having oral sex with someone who has genital herpes (where painful blisters develop on and around the genitals).

Read more about the causes of cold sores.

Herpes simplex virus

The herpes simplex virus – or "cold sore virus" – is highly contagious and can be easily passed from person to person by close direct contact. After someone has contracted the virus, it remains dormant (inactive) for most of the time.

However, every so often the virus can be activated by certain triggers, resulting in an outbreak of cold sores. These triggers vary from person to person but can include fatigue, an injury to the affected area, and, in women, their period.

Some people have frequently recurring cold sores (around two or three times a year), while others have one cold sore and never have another. Some people never get cold sores at all because the virus never becomes active.

Treating cold sores

Cold sores usually clear up by themselves without treatment within 7 to 10 days.

However, antiviral creams are available over the counter from pharmacies without a prescription. If used correctly, these can help ease your symptoms and speed up the healing time.

To be effective, these treatments should be applied as soon as the first signs of a cold sore appear (when you feel a tingling, itching or burning sensation around your mouth). Using an antiviral cream after this initial period is unlikely to have much of an effect.

Cold sore patches are also available that contain hydrocolloid gel, an effective treatment for skin wounds. The patch is placed over the cold sore while it heals.

Antiviral tablets may be prescribed for severe cases.

Read more about treating cold sores.

Complications of cold sores

Cold sores are usually mild. However, in rare cases, they can cause complications.

Dehydration sometimes occurs if drinking fluids becomes painful. Young children are particularly at risk of becoming dehydrated.

The herpes simplex virus can also spread to other parts of your body. This is known as a secondary infection. It can sometimes cause painful sores called whitlows to develop on your fingers.

Read more about the complications of the herpes simplex virus.

Preventing infection

It is not possible to completely prevent becoming infected with the herpes simplex virus or to prevent outbreaks of cold sores.

Cold sores are at their most contagious when they burst (rupture), but remain contagious until they are completely healed. You should therefore avoid close contact with others until your cold sore has completely healed and disappeared.

If you have unhealed cold sores, it is particularly important to avoid close contact with people with weakened immune systems because they are more vulnerable to infections.

For example, you should avoid close contact with:

  • newborn babies (never kiss a newborn baby if you have a cold sore)
  • people with HIV
  • people receiving treatments that are known to weaken the immune system, such as chemotherapy

Read more about preventing a herpes simplex infection.

Page last reviewed: 10/04/2014

Next review due: 10/04/2016


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The 14 comments posted are personal views. Any information they give has not been checked and may not be accurate.

Buddys mum said on 25 September 2014

I'm just starting with a coldsore today, been using blistex for a chapped nose from blowing my nose due to a cold I'm just getting over woke up this morning and my lip was tingling and a coldsore is coming so started with the blistex right away.

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Ivett Avalos said on 25 September 2014

I don't have cold sores but I do have herpes and hemoform Serum helps the sore heal faster and takes he pain away! It is expensive but it lasts a long time.

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Godders45 said on 18 September 2014

My 5 year old daughter started having cold sores 2 years ago and it's driving me mad. She gets them every time in exactly the same place on her lower lip. Unfortunately they take about 10 days to disappear but she's often had bouts of them with only a few weeks in between without one. Doctor has gave us cream a few times and another told us to just 'let it run its course' but they are very sore and she finds them upsetting. I've taken to using patches to help minimise the soreness for her but I really want a solution. Has anyone else had a child suffer like this? I can't believe she got them so young :(

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LulaP said on 10 September 2014

To update, I commented on the treatment section of this topic a while ago. I've tried everything under the sun (lysine, light treatment, patches, creams, diet alterations, controlling my stress, aloe vera gel, teabags.. etc!!) I've since been back to my doctor a few times and had been told various things (as you get older they will become less severe, don't get stressed), but I changed jobs and went through 8 weeks of continuous cold sores, saw my doctor again and explained (again!) that it was at least once a month, every month for 6 years...
He has prescribed me Aciclovir to take twice daily - every day, until further notice. I cried once I received my prescription, I felt so relieved. I've been taking them for 3 months and I will sometimes still get the tingles but nothing comes up. I feel very lucky. I would advise if you are a serious case to keep going back to your doctor!

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S336 said on 28 April 2014

So i have been suffering from cold sores since the age of 13. i used to get them about 3 times a year and it has since been increasing. I am 22 now, and I get cold sores on my lips 2-3 times a month, depending on how long the healing process takes.
I noticed that coconut milk was making it worse and so i have completely stopped consuming it, along with lemon and other strong acidic fruits.

I really do not know what to do to stop this from happening as it is so embarrassing and disgusting to look at. Its so out of control i can't even kiss my boyfriend anymore.

help me please!

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FSD17 said on 17 April 2014

I am unfortunately prone to cold sores! I have been ill this week and I know have a cold sore both in the middle of my upper and lower lip and a cluster of 4 in the right hand bottom corner. They are taking over my lips! I have covered them in cold sore cream. Any tips on getting rid of these quicker?

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ANNE McLAREN said on 12 April 2014

Hi... I get a bad cold sore (HSV-1) maximum of once per year.

Last years preluded being bed ridden with flu.
This year I am able to go out & about.
Symptoms...? Days prior i had a swollen lymph node at the back of my throat, fatigue, feeling forgetful, feeling like a lead weight, very sore lower back, stomach pains, sore head and neck.
This time my cheeks became flushed like I was blushing. I have a swollen lymph gland under my chin and its pretty painful. Feeling very sorry for myself. Zovirax is helping... as are ibuprofen for the fever & aches etc

Hope this helps!

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deefadog said on 09 March 2014

I have been getting these cold sores inside my nostrils since I was 16! They use occur randomly in either nostrl! And most of the time my glands in my throat would inflame and become sore and the side of my face where the infection would be would become very sore also!

Lately though I have the same cold sore for months and it refuses to go! Its getting My down to be honest!

They sometimes creap on to the outside of the nose which is not a very nice thing to go out in public with!

To treat them I usually have lipsore cream which I apply in my nose with a cotton bud 4-5 times a day! After a week it normally goes!

Is there another treatment available?

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annie44 said on 19 November 2013

I'm aged 69 and have a cold sore on my lip for the first time in my life! I don't know where it came from and was surprised at the comment about them also being inside your nose. A while ago, I suffered a sore 'patch' inside my nostril and wonder if that's where it could have come from?

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amy8521 said on 19 May 2013

I just wanted to add: cold sores aren't just on your lips! I get cold cores on my nose, sometimes inside the nostril, mostly the blisters creep out onto the end of my nose. A bit unsightly; I often feel the need to explain what it is, as everyone assumes cold sores are just on your lips.

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SuwakoMoriyaChan said on 14 March 2013

I contracted a cold sore just under my right eye when I was about two and it kept coming back every 8 weeks! My parents of course took me to the doctors who were really confused as to what it was. I was referred to dermatology who were just as flustered. In the end I was seen by a panel of 12 of Northern Ireland's best dermatologists, who put it down to just being a cold sore. It came back less frequent as I got older but since I moved to England (about 5 years ago) it has not come back until now! I've recently began GCSE work which is really stressing me out, so maybe that is the trigger?? It was really big this time; bigger than a two pence coin, which is unusual too. Furthermore, it has been infected by bacteria (I know sounds disgusting) but my whole cheek has swollen and the blisters are kind of leaving but it looks green! I got some blackmail at school, saying I need to stay away, it's extremely contagious, it's impetigo when it's not! (BTW, told nobody it was a cold sore =\). Couldn't face going to school today so just stayed at home and rested; probably needed the day off because the virus is making me feel run down and also some other pre-existing medical conditions.
Hope nobody gets it as bad as mine xxx

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sophie1818 said on 22 January 2013

I'm prone to getting cold sores, particularly when stressed, (i am stressed at the moment due to exams) but I've had one on the left side of my mouth since just before Christmas and am wondering if I should go and see a doctor about it? It went away for about a week and now it's come back in exactly the same place and looks slightly more inflamed than normal.

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whiston78 said on 02 August 2011

i got a cold sore just after getting a virus but i take bio flavorloids plus lysine supplements to prevent this from happening.i am wondering whether you can over boost your immune system by taking this daily and can i stop the cold sore fully coming out.

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curiouscupcake said on 18 March 2011

Despite reading this, I'm not sure if I have a cold sore or not. I had a thing that looked like a spot right next to my mouth,but It was very sore. I have popped the spotlike thing. But I'm worried that its a cold sore, as it was sore and a relative thought it looks like a cold sore.

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