Cold sore

Cold sore: causes, stages, treatment

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Cold sore: causes, stages, treatment Cold sore: causes, stages, treatment Cold sore: causes, stages, treatment

What are cold sores?

Cold sores, also called herpes or fever blisters, are groups of small, fluid-filled blisters. The blisters are most often gathered in patches on the lip and around the mouth. Before an outbreak, you often feel a tingling sensation or stinging pain. Then the blisters appear, and they usually burst, ooze, crust over and disappear after several days to two weeks. If you don’t treat your cold sore, it usually lasts 7-10 days, but can remain for up to two weeks. Although there is no cure for cold sores, you can control the pain, the severity of the outbreak and you can help speed up the healing process.

Cold sores are caused by a virus, the herpes simplex virus type 1 (HSV-1). There are two types of the herpes simplex virus: HSV-1 and HSV-2. The former is responsible for herpes labialis, a herpes located around the mouth, most commonly on the lips. This type of herpes is the one commonly referred to as cold sores or fever blisters, while HSV-2 causes genital herpes. Generally speaking, herpes is a rash of the skin and mucous and is characterized by reddening of the affected area followed by blister formation, which can burst and thus lead to scabs.

Cold sores cannot only be irritating but can also be embarrassing with social, and emotional impact. In extreme cases, it may lead to social isolation. If you suffer from cold sores, you are not alone. About two-thirds of people under the age of 50 years are infected with herpes simplex virus type 1 (HSV-1), the virus responsible for cold sores[1].

In Europe, this corresponds to a little bit more than 200 million women (69%) and 187 million men (61%). The infection is mostly asymptomatic but can cause mild symptoms or painful blisters.

Are cold sores contagious?

Cold sores are contagious from the initial symptoms to the resolution. From days 1-2, cold sore blisters are full of the virus which spreads through saliva, skin-to-skin contact, or by touching an object handled by someone infected with the virus.

You can spread the virus even when you do not have any apparent symptoms of a cold sore yet. However, this is much less likely than if contact occurred when a cold sore is present.
The fluid in the blisters contain the virus, therefore cold sores are most contagious when the blisters ooze. The first cold sore episode will generally occur two to 20 days after being in contact with an infected person.

How long are cold sores contagious?

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Dispelling Common Myths About Cold Sores

Cold sores are contagious until they completely go away, which usually takes about two weeks. Cold sores are the most contagious when fluid seeps out of the sores. Once the sore has scabbed over, the risk of passing on the virus decreases significantly, but that does not mean it is no longer contagious. Your scab can be broken while eating or smiling, and the fluid can leak out.

Can I give cold sores to other people?

Cold sores can be passed on more easily when you are having an outbreak and active sores or blisters are present on the skin. However, the herpes virus can still be spread even if there are no signs or symptoms.

Cold sores are the most contagious when fluid seeps out of the sores.

How to be less contagious

You should minimise any contact with the sores. Always wash your hands after contact with a cold sore to avoid spreading the virus from one site to another, such as the eyes, nose, or fingernails.

Until the cold sore blisters and scabs have completely gone away, you have to protect yourself and other people from infection. Airtight and watertight treatments such as COMPEED® cold sore patches help prevent the virus from spreading to another area of your body as well as protecting others.

How long do cold sores last?

If you don’t treat your cold sore, it usually lasts 7-10 days, but can remain for up to two weeks.
When a person first contracts the virus, a cold sore usually occurs within a few days. Signs and symptoms may vary, depending on whether it is the first outbreak or a recurrence, the latter tending to be less severe. Cold sores often recur in the same spot as before and the development of a cold sore typically progresses via five stages over a 7-10 day period. The early stages are the most painful and sensitive.

How do you get cold sores? - The triggers

After you have contracted the virus, it remains inactive most of the time. However, every so often, the virus can be re-activated by certain triggers, resulting in an outbreak of cold sores. These triggers are of two kinds:
Linked to a personal condition

  • Illness: fever, flu, or cold
  • Trauma and stress including physical strain and emotional stress
  •  Fatigue or lack of sleep
  • Hormonal changes, especially from menstruation or taking birth control pills
  • Minor injuries such as cracks in the lips
  • Weakened immune system due to unhealthy lifestyle (smoking, alcohol, and poor nutrition) or certain medicines such as chemotherapy

Linked to outdoor conditions

  • Excessive sun exposure: sunlight and artificial UV light
  • Skin exposure to extreme weather conditions (heat, cold or wind)

Reactivation of virus

Once you contract the HSV-1 virus, it usually causes an initial outbreak of cold sores. Then the virus remains in your body for the rest of your life. However, you will not get a cold sore while the virus lies dormant in the body between outbreaks. Many factors can wake up the virus which in turn, starts replicating and spreading. At the same time, the immune system tries to fight back the virus, and this results in inflammation (pain and redness).

Preventing Cold Sores

Most of these potential triggers cannot be completely avoided, or are difficult to avoid. But you can try to alter your habits to reduce the risk of re-igniting the virus.
Managing your stress by playing sport, practising meditation and yoga or simply by taking time for yourself are just some of the ways to try to avoid new flare-ups.
When the seasons change, your lips can dry out very quickly and become cracked. Hydrating them with a balm is the best defence against chapped lips. If sunlight triggers your cold sores, a sunblock lip balm (SPF 15 or higher) could be helpful.

Knowing yourself well

Knowing and recognising your triggers is a huge asset in managing outbreaks. To do this, it can be helpful to keep a journal where you record your stress level, the events that mark your daily life, what you eat, how you sleep, etc. Identifying the events that trigger new outbreaks will allow you to be proactive in preventing them in the future.

What does the beginning of a cold sore look like?

  • Typically, the first signs of a cold sore starting are tingling, itching or burning feeling usually around the mouth. Next, blisters filled with fluid start to appear. It is worth remembering that while blisters typically tend to form around the mouth and nose they can appear anywhere on your face. Most people notice cold sores starting after specific triggers, commonly cold weather or stress.
  • Stage 1: Tingling stage – For more than 85% of cold sore sufferers, outbreaks often begin with symptoms such as a tingling, tightness, soreness, or itching around the lips. This stage lasts 1-2 days. Most often, the tingling sensation is experienced around the area where the cold sore will appear. The area then starts to swell and redden, and can feel painful to touch. Remember that a cold sore is contagious from the moment you first feel tingling or other signs of a cold sore coming on because the virus has already replicated.
  • Stage 2: Blister stage – Within 48 hours of the first stage, clusters of red, fluid-filled blisters appear. This is the result of the virus waking up, multiplying, and your body beginning to fight back. The blisters start to fill with clear fluid. This fluid is highly infectious, as it contains the cold sore virus (HSV-1, herpes simplex virus type 1). If the blister bursts, it releases the contagious fluid, potentially leading to infection of other parts of your body or other people.
  • Stage 3: Weeping – On day 4 or 5 of an outbreak, the blisters usually burst, ooze, and form painful sores. Open sores are red and shallow. Be aware that cold sores are most contagious during this time. The exposed and ulcerated sores will now begin to scab over as your body starts the healing process.
  • Stage 4: Crusting – Around days 5-8 of an outbreak, you most likely will have developed scabs. The sores have dried out and scabbed over causing itching and painful cracking. When the blister dries out without bursting, scabs look yellow or brown.
  • Stage 5: Resolution with healing – The final stage of the cold sore is the healing phase. Once your body’s defences have tackled the virus, the scabs begin to peel off and the cold sores heal. Try to avoid knocking off the scab because the healing process will need to start again. For most people, the healing occurs between 8 to 10 days after the onset of symptoms. Typically, cold sores do not leave scars.

Can cold sores be cured?

As the virus never leaves your body after the initial breakout, it cannot be cured, but the symptoms can be managed. Up to several hours or a day before the cold sore appears, you will most likely feel a tingling or itching around the lips.

COMPEED® Cold Sore Patches can help to prevent cold sores worsening and severity of scabbing, and to promote fast healing; they contain active hydrocolloid gel technology developed to heal cold sores fast. As these patches are designed to be discreet, COMPEED® Cold Sore Discreet Healing Patches additionally avoid social embarrassment[2]. You can use these patches at any stage of an outbreak. The general principle remains: the sooner, the better. COMPEED® Cold Sore Discreet Healing Patch will not only help your sores to heal fast, but relieve the pain and reduce the risk of contamination from the wound. By providing a protective barrier, the patch effectively helps reduce the risk of spreading the virus to other people. These patches have been proven to be very effective for the treatment of herpes labialis whilst protecting your wound from external environmental factors at the same time.

Another option is to take antiviral medicines to stop the virus from replicating and thus prevent cold sores from developing, or at least reduce their size and the healing time. Antivirals for the treatment of cold sores usually come as either pills or creams.

Warning for babies and people with a weak immune system

Adults who have a cold sore should take care not to kiss babies or let babies touch the sore for two reasons.
Cold sores are usually pretty harmless, but they can become severe in people with not yet fully developed immune systems. The immune system usually protects the body from infection. A person with a weak immune system is likely to get more severe infections than most other people. In that context, the cold sore virus can be dangerous for babies less than 6 months old. Once the baby has been infected, they will be prone to cold sores for the rest of their lives.
The same precaution must be taken with people affected by HIV (human immunodeficiency virus) and people suffering from cancer and treated with chemotherapy. It is, therefore, important to remain particularly vigilant with these people and take steps to avoid infecting them with HSV.



World Health Organization – Herpes simplex virus (January 2017) –


Karlsmark T et al. Randomized clinical study comparing Compeed® Cold Sore Discreet Healing Patch to acyclovir cream 5% in the treatment of herpes simplex labialis. J Eur Acad Dermatol Venereol. 2008 Nov;22(10):1184-92. doi: 10.1111/j.1468-3083.2008.02761.x

Samuelle Yohou
Samuelle Yohou
Medical Manager at HRA Pharma since March 2021, Samuelle Yohou is responsible for ensuring information published on COMPEED’s UK and Ireland websites is accurate and up to date from a medical and regulatory perspective.