Why do I keep getting cold sores? If a familiar tingle on your lip has turned into a blister for the third time this year, the answer is not bad luck, and it is not poor hygiene. It is a virus you almost certainly picked up years ago, probably as a small child, that has been quietly living in the nerves of your face ever since. November is when it tends to show up again, because the winter cold season has arrived, and a cold or a fever is one of the triggers the NHS lists for an outbreak.
Cold sores are small blisters that develop on the lips or around the mouth, caused by the herpes simplex virus, usually type 1, known as HSV-1. The World Health Organization estimates that about 3.8 billion people under the age of 50 worldwide carry HSV-1, around 64 per cent of that age group. Most people never have a single blister. For the rest of us, the virus wakes up from time to time, and the sore comes back in roughly the same place. A cold sore usually clears up without treatment within 7 to 10 days, and there is no cure, but there is plenty you can do to shorten an outbreak, protect the people around you, and cut the number of times it returns.
What is a cold sore, exactly?
A cold sore is a cluster of small, painful blisters on or around the lips, caused by the herpes simplex virus. In most cases the culprit is herpes simplex virus type 1, or HSV-1. Sometimes cold sores are caused by herpes simplex virus type 2, HSV-2, which can happen after oral sex with someone who has genital herpes. The two types are closely related, and the cold sore itself looks and behaves the same whichever type caused it.
Most people meet the virus in early childhood. NHS Inform explains that the virus is usually passed on when a child is kissed by a family member or friend with a cold sore. The virus passes through the skin and travels up the nerves, where it lies inactive, or dormant, until it is triggered at a later date. That first infection often causes no symptoms at all, which is why many adults with cold sores have no memory of ever catching anything.
When the first infection does cause symptoms, they can be quite severe, and they are most likely to develop in children younger than 5. The NHS describes swollen and irritated gums with small, painful sores in and around the mouth, a condition called herpes simplex gingivostomatitis, along with a sore throat, swollen glands, more saliva than normal, a high temperature of 38C or above, dehydration, nausea and headaches. Gingivostomatitis usually lasts 7 to 14 days, with the sores taking up to 3 weeks to heal. Adults rarely get these first-infection symptoms, but when they do they are similar: a sore throat with or without swollen glands, bad breath, and painful sores in and around the mouth that can develop into ulcers with grey or yellow centres.
After that first infection, the picture changes. The virus settles in the nerves and, for most people, later outbreaks are reduced to just the cold sores themselves, without the sore throat and swollen gums of the first episode. The sore tends to return to roughly the same spot each time, because the virus travels back down the same nerve.
Why do cold sores keep coming back?
The short answer is that the virus never leaves. Once HSV-1 has settled in a nerve, it stays there for life, mostly asleep. Every so often something wakes it up, it travels back down the nerve to the skin, and a new blister appears. How often that happens varies a great deal from person to person. Some people get several outbreaks a year, some get one every few years, and many people who carry the virus never get a blister at all.
The NHS lists the things that can trigger an outbreak: having another infection, such as a respiratory tract infection; having a high temperature or fever; emotional upset or psychological stress; tiredness and fatigue; an injury to the affected area; menstruation; and strong sunlight. Often, though, there is no obvious trigger at all, and the sore simply appears.
That trigger list explains why November is cold sore season for so many people. It is not the cold weather itself that causes the outbreak. It is the winter cold season: respiratory infections spread, fevers follow, sleep gets shorter and stress builds, and each of those is a listed trigger. A cold sore that arrives the week after a heavy cold is not a coincidence. It is the virus taking advantage of a body that is already busy fighting something else.
It is worth saying plainly what a cold sore is not. It is not a sign of a dirty mouth or bad hygiene. It is not caused by a vitamin deficiency, and it is not something you can catch from a toilet seat or a swimming pool. It is a common virus that most of the world already carries, and an outbreak is the virus reactivating, not a new infection.
What does a cold sore look like as it heals?
Most cold sores follow the same course, and recognising the stages helps you act at the right moment. It usually starts with a warning: a tingling, itching or burning feeling on the lip, sometimes with a little tenderness, a day or so before anything is visible. This is the stage that matters most for treatment, because antiviral cream works best when it is used as soon as you recognise that early tingling feeling.
Next, small painful blisters appear, often in a cluster, filled with clear fluid. The blisters then burst and weep, which is when the sore is at its most contagious. A scab forms over the area, and finally the scab falls off and the skin underneath heals. The whole process usually takes 7 to 10 days, and the NHS advises that a cold sore should start to heal within 10 days. If it has not started to heal by then, that is a reason to speak to your GP.
It is important to know that a cold sore is contagious from the moment you first feel tingling or other signs of one coming on, not just once the blister is visible, and it stays contagious until it has completely healed. That early contagious window is why the tingling stage is the moment to change your behaviour as well as to reach for the cream.
What actually helps a cold sore heal faster?
There is no treatment that makes a cold sore vanish overnight, and anyone promising one is selling something the evidence does not support. What does help is acting early and looking after the sore while it heals. The NHS advice is practical rather than dramatic, and it works.
The single most useful step is to use antiviral cream as soon as you recognise the early tingling feeling. A pharmacist can recommend an antiviral cream to speed up the healing time, and the NHS notes that these creams do not always work after the blisters have appeared, so timing is everything. Keep a tube at home if you get cold sores regularly, so you are not waiting for a pharmacy trip while the window closes. A pharmacist can also recommend creams to ease pain and irritation, and cold sore patches, which protect the skin while it heals.
For pain and swelling, paracetamol or ibuprofen can help, and both come in liquid form for young children. Do not give aspirin to children under 16. Eat cool, soft foods if the sore makes eating uncomfortable, and drink plenty of fluids to avoid dehydration, which the NHS flags as a particular risk for young children.
There are a few simple habits that make healing easier. Wash your hands with soap and water before and after applying cream. Dab cream on rather than rubbing it into the sore. Use a sunblock lip balm with SPF 15 or above if you are outside in the sun, since strong sunlight is a listed trigger. If brushing your teeth is painful, an antiseptic mouthwash can help. And avoid acidic or salty foods if they make your cold sore feel worse.
What should you not do? Do not touch your cold sore apart from applying cream, and if you do touch it, wash your hands. Do not kiss anyone while you have a cold sore, and do not have oral sex until it has completely healed, because you could pass the virus on as genital herpes. You will also see electronic devices sold in pharmacies that treat cold sores with light or lasers. NHS Inform is honest about these: some people find them helpful, but there have not been many studies to confirm if they work. The same caution applies to supplements marketed for cold sores. NHS guidance lists no vitamin or supplement for cold sores, so money spent there is better spent on an antiviral cream used early.
How long are cold sores contagious, and how do you stop spreading them?
Cold sores are contagious from the moment you first feel tingling until the sore has completely healed and disappeared, and they are at their most contagious when they burst. The NHS advises avoiding close contact with others until the cold sore has completely healed. That means no kissing, no oral sex, and no touching the sore and then touching someone else without washing your hands first.
There is one reassurance worth knowing. There is no need to stay away from work or miss school if you or your child have a cold sore. The virus spreads through close contact, not through the air, so normal daily life can continue with a little care. The practical rules are simple: wash your hands often, do not share anything that touches the sore, and keep the sore covered with a patch if it helps you leave it alone.
If someone in your household has a cold sore, the risk to everyone else is low as long as the sore is left alone and hands are washed. The people who need the most protection are not other healthy adults, who very likely already carry the virus themselves, but newborn babies, pregnant women and people with a weakened immune system, who may be referred to hospital for advice or treatment if they develop a cold sore.
The rule that matters most: babies and cold sores
This is the most important section of this article, and it is the one to remember if you remember nothing else. Kissing a baby if you have a cold sore can lead to neonatal herpes, which the NHS describes as very dangerous to newborn babies. Neonatal herpes is a herpes infection in a young baby, and it is rare in the UK, but it can be very serious because a young baby’s immune system has not fully developed to fight off the virus.
The virus can be passed to a baby through a cold sore if a person with a cold sore kisses the baby. It is thought that the baby is most at risk in the first 6 weeks after birth. Healthier Together, the NHS service for parents, puts the scale at around 7 babies in every 100,000 babies born in the UK. Rare, in other words, but dangerous enough that the prevention advice is absolute.
If you develop a cold sore, or have any signs of a herpes infection, do not kiss any babies. Everyone should wash their hands before handling a baby, and people with a current cold sore, or a recent history of cold sores, should not kiss a baby at all. The NHS advises discouraging anyone who is not a close family member or carer from kissing a baby, and says the safest place to kiss a baby is on the top of the head, avoiding the mouth, nose and eyes. People with a known herpes infection should avoid touching a baby unless they are a close family member or carer, and in that case they should carefully wash their hands first.
This applies even if there is no visible sore at the time. Healthier Together notes that it is possible for people to spread the herpes virus even when they do not have a visible cold sore, so hand washing matters for everyone who handles a newborn, not just people with an obvious blister. If a newborn baby develops symptoms that worry you, contact your health visitor or GP, and babies with a herpes infection need antiviral treatment as quickly as possible.
When should you see a GP?
Most cold sores never need a doctor. You can get advice and treatment directly from a pharmacy, and a pharmacist will tell you if you need to speak to a GP. The NHS lists the situations where a GP visit is the right move: the cold sore has not started to heal within 10 days; you are worried about a cold sore or think it might be something else; the cold sore is very large or painful; you or your child have swollen, painful gums and sores in the mouth; or you have a weakened immune system, for example because of chemotherapy, diabetes or HIV.
There are two more situations to take seriously. If the infection reaches your eye, which the NHS lists as a possible complication called herpetic keratoconjunctivitis, with swelling and irritation of the eye area and sores on the eyelids, seek medical advice promptly, because eye involvement needs proper assessment. And if your cold sores are very large, painful and keep coming back, your GP may prescribe antiviral tablets, which are a step up from the creams a pharmacist can sell you. Newborn babies, pregnant women and people with a weakened immune system who have cold sores may be referred to hospital for advice or treatment.
Other complications are rare, but the NHS lists them so you know what to watch for: skin infections, which often happen if the virus comes into contact with broken skin, such as a cut or graze, or a skin condition such as eczema; herpetic whitlow, which causes painful sores and blisters on and around the fingers; and dehydration, which sometimes occurs if drinking fluids becomes painful, with young children particularly at risk.
Can you stop cold sores coming back?
Honestly, not completely. NHS Inform states it plainly: it is not possible to prevent infection with the herpes simplex virus or prevent outbreaks of cold sores. There is no vaccine and no treatment that removes the virus from your nerves. Anyone selling a permanent cure is selling something that does not exist.
What you can do is cut the number of outbreaks and make the ones that happen shorter and milder. Start by learning your own triggers. If your outbreaks follow colds, fevers, stressful weeks or broken sleep, those are the patterns to act on: rest properly when you are ill, look after your sleep, and manage stress where you can. Use a sunblock lip balm with SPF 15 or above when you are outside in strong sun. Keep antiviral cream at home so you can use it at the first tingle rather than after the blister appears.
If your cold sores are frequent, very large or very painful, talk to a pharmacist first and then to your GP, who may prescribe antiviral tablets. That is the only step beyond the creams that NHS guidance offers, and it is reserved for the people whose outbreaks are severe or keep coming back. For everyone else, the plan is simple and unglamorous: act at the tingle, protect the sore, keep it away from other people and from babies, and let it heal. The virus will still be there next winter, but you will be ready for it.
Frequently asked questions
Why do I keep getting cold sores?
Why do I keep getting cold sores? Because the herpes simplex virus, usually HSV-1, stays in the nerves of your face for life after a childhood infection, and it wakes up when you are ill, stressed, tired or run down. Triggers listed by the NHS include another infection such as a respiratory tract infection, a fever, emotional upset, tiredness, injury to the area, menstruation and strong sunlight, and often there is no obvious trigger at all. About 3.8 billion people under 50 worldwide carry HSV-1, according to the World Health Organization, so a recurring cold sore is common, not a sign of poor hygiene. There is no cure, but antiviral cream used at the first tingle can shorten an outbreak.
How long does a cold sore last?
A cold sore usually clears up without treatment within 7 to 10 days. It starts with tingling or itching, then small blisters appear, burst and weep, a scab forms, and the skin heals. The NHS advises that a cold sore should start to heal within 10 days. If it has not started to heal by then, or if it is very large or painful, speak to your GP. Antiviral cream used at the first tingling can speed up healing, but it does not always work once blisters have appeared.
Are cold sores contagious?
Yes. Cold sores are contagious from the moment you first feel tingling or other signs of one coming on until the sore has completely healed, and they are at their most contagious when they burst. Avoid kissing anyone and avoid oral sex until the sore has completely healed, wash your hands before and after applying cream, and avoid close contact with others until it has gone. There is no need to stay away from work or miss school if you or your child have a cold sore.
Can I kiss my baby if I have a cold sore?
No. Kissing a baby if you have a cold sore can lead to neonatal herpes, which the NHS describes as very dangerous to newborn babies. The risk is highest in the first 6 weeks after birth, and neonatal herpes affects around 7 babies in every 100,000 born in the UK. Do not kiss any babies while you have a cold sore, wash your hands before handling a baby, and remember that the safest place to kiss a baby is on the top of the head. If a newborn baby develops worrying symptoms, contact your health visitor or GP urgently.
What is the fastest way to get rid of a cold sore?
There is no way to make a cold sore vanish overnight. The fastest option the NHS supports is antiviral cream used as soon as you recognise the early tingling feeling, before blisters appear. A pharmacist can also recommend creams to ease pain and irritation, and cold sore patches to protect the skin while it heals. Paracetamol or ibuprofen can ease pain and swelling. Light and laser devices sold in pharmacies have little study evidence behind them, and NHS guidance lists no vitamin or supplement for cold sores. With early treatment and simple care, most cold sores heal within 7 to 10 days.
Related reading
Sources
- NHS Inform, Cold sore, https://www.nhsinform.scot/illnesses-and-conditions/mouth/cold-sore/
- NHS, Cold sores, https://www.nhs.uk/conditions/cold-sores/ (page last reviewed 19 February 2024)
- NHS, Neonatal herpes (herpes in a baby), https://www.nhs.uk/content-widgets/health-a-to-z/neonatal-herpes (page last reviewed 24 July 2025)
- Healthier Together NHS, Neonatal Herpes Simplex Virus Infection, https://www.healthiertogether.nhs.uk/new-parent-and-baby/neonatal-herpes-simplex-virus-infection
- World Health Organization, Herpes simplex virus, https://www.who.int/news-room/fact-sheets/detail/herpes-simplex-virus (fact sheet, 30 May 2025)
