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Herpes Labialis (Cold Sores)

  1. What is herpes labialis?
  2. Symptoms
  3. Causes
  4. Treatment
  5. FAQs
  6. Other names for herpes labialis

What is herpes labialis?

Herpes labialis, or cold sores, is a viral infection caused by herpes simplex virus 1 (HSV-1), which is the type most commonly associated with cold sores, or herpes simplex virus 2 (HSV-2), which is usually associated with genital herpes. Herpes labialis presents with painful blisters of the lips and facial area near the mouth. It is highly contagious, and it is estimated that 50% to 80% of the adult population in the USA carries the herpes simplex 1 virus.[1]

Most people are infected with herpes labialis in childhood, after which it lies dormant in the nervous system, usually in major nerves of the upper body.[2] Stress can cause the virus to reactivate, leading to an outbreak of the blisters. Herpes labialis outbreaks that result from a reactivated infection are known as recurrent infections. Because the blisters often occur during or just after an illness, such as a cold or flu, they are colloquially known as “cold sores” or “fever blisters.” The condition is also sometimes called orofacial herpes or oral herpes.

Although herpes labialis is contagious, painful and unsightly, it is a very minor infection in most people. However, there can be serious health consequences if newborn babies (see FAQs) or people who are immunosuppressed are affected .

Herpes labialis symptoms

Because cold sores are recurrent, they typically arise after encountering triggers such as sunburn or illness, and it is possible to predict when they are likely to occur and therefore to be vigilant about symptoms. Redness and tingling at a particular site around the mouth and lips often the first sign that herpes labialis is occurring. Shortly thereafter, fluid-filled blisters appear. If you are concerned that you or someone you know may have cold sores, the Ada app can help you check your symptoms. Find out more about how the app works.

Good to know: Herpes labialis caused by herpes simplex virus 1 is contagious, and recurrent infection can occur, which means that an affected person may experience the same symptoms every time they have an outbreak.

Patients may be completely asymptomatic at the time of their first infection with herpes simplex virus 1 or herpes simplex virus 2, but in some cases symptoms do appear. In children, these include:

  • Fever
  • Gingivostomatitis, i.e. inflammation and blisters on all oral mucosa, including the lips, tongue and inside of the mouth.

In adults, symptoms of herpes labialis resulting from herpes simplex virus 1 can include:

  • Sore throat
  • Swollen cervical lymph nodes

Formerly, most people were exposed to herpes simplex virus 1 and herpes simplex virus 2 as children. However, the age of first exposure has been rising in the West, and it is now common to be infected for the first time via oral-genital contact.[2]

Herpes labialis differential diagnosis

It is important to distinguish between cold sores and other skin infections of the face and mouth.[3] If pus is present, it is more likely to be a pimple or boil. If the blister is inside the mouth, it is a mouth ulcer rather than a cold sore. The first time an HSV infection occurs, however, it can present with mouth ulcers.

Impetigo, which can co-occur with cold sores in warm and humid climates, first manifests as pus-filled blisters that form golden-brown scabs. As impetigo is a bacterial infection, it will not respond to cold sore treatments. Blisters resulting from impetigo often spread further around the lips and mouth than cold sores do. If it is not clear whether the blisters are cold sores or impetigo, it is best to consult a physician.[4]

Herpes labialis causes and transmission

Herpes labialis is very contagious. It is spread by coming into contact with the virus via the cold sore itself, coming into contact with the saliva of someone who currently has a blister, or by sharing plates, cups, eating utensils, towels, face-cloths, toothbrushes, tooth-mugs or razors with someone who currently has a cold sore. People who have a family member or intimate partner with an active cold sore are most at risk.

An outbreak of herpes labialis is caused by the reactivation of a dormant herpes simplex virus 1 or herpes simplex virus 2 infection. Factors that can cause the infection to reactivate and lead to recurrent infection include:[1][2]

  • Fever
  • Illness, particularly upper respiratory tract infections
  • A weakened immune system
  • Dental work
  • Menstruation
  • Exposure to strong sunlight; cold sores often follow sunburn on the face
  • Physical stress such as surgery
  • Emotional or psychological stress
  • Eczema

Transmission of the herpes simplex 1 virus can also occur through kissing or by oral-genital contact. Oral-genital contact with someone who has a cold sore can cause genital herpes.[2] Two closely-related viruses cause herpes labialis: HSV-1 and HSV-2. HSV-2 is more often the cause of genital herpes, though both can be spread by oral sex, and both can cause genital herpes.[1] Most people experience fewer reactivations of the infection after the age of 35.

Herpes labialis stages

Herpes labialis infections have several stages:[5][6][7]

  1. Prodromal or tingle stage: This stage lasts one or two days, during which the patient experiences tingling and possibly reddening at the site at which the blister will appear. Cold sores may repeatedly occur at the same site. If treatment is administered during this stage, the entire duration of the infection can be shortened.
  2. Blister stage: This stage lasts for two or three days, during which blisters appear on and around the lips, philtrum or nostrils. The appearance of the blisters is usually accompanied by mild pain, which can be worsened by speaking, laughing or eating.
  3. Weeping stage: This stage is the most painful. It lasts one to three days, during which time the blisters rupture and may weep clear fluid.
  4. Crusting stage: The blisters form a scab. This phase is often itchy. Patients often find this stage the most troublesome, due to the itchiness.
  5. Healing stage: In this phase, the scabs fall off. Small, temporary scars may be present while the skin heals.

It should be noted that herpes labialis is contagious in all stages, but particularly so during stage three. The infection usually resolves on its own, and a person will stop being contagious to others when the skin heals.

If you are not sure if this matches what you’ve been experiencing, check your symptoms with Ada.

Herpes labialis treatment

Cold sores are easily treated. Various medications and home remedies can be used to manage herpes labialis caused by herpes simplex virus 1.

Herpes labialis medication

If the patient is vigilant and recognises the herpes labialis infection while it is still in the tingle stage, a topical over-the-counter antiviral cream, such as an acyclovir cream, can be applied. This will shorten the lifespan of the blister considerably. Applying creams once the blister has appeared is less effective. Antivirals that are commonly used against herpes labialis are aciclovir/acyclovir, and penciclovir, also known as pencyclovir.[2]

Alternatively, creams such as zinc oxide, zinc sulfate or anesthetic creams may be applied to give relief. Although these creams reduce painfulness and can shorten the lifespan of the blister, they are not as effective as antiviral creams.

Oral antivirals (tablets) are sometimes prescribed by doctors, usually for very severe cases. Most cases of herpes labialis do not need oral antivirals, and they are only really effective if treatment begins during the prodromal phase. However, if a patient has already developed blisters, doctors may prescribe oral antivirals, so that the patient has them on hand to use as prophylaxis in case of future outbreaks, rather than for use in the current outbreak.

There is some evidence that oral antivirals can be most effective if they’re prescribed in cases where a patient’s cold sores have a known trigger, such as strong sunlight.[8] In such cases, making sure that the affected person has oral antivirals to hand immediately after experiencing a trigger, means that they will be able to stop the outbreak before it moves out of the prodromal phase. This is known as “suppressive” therapy. It is a form of herpes labialis prophylaxis.

Valciclovir, also known as valcyclovir, is often administered in 2g doses twice daily and can reduce duration. Likewise, 400mg of aciclovir/acyclovir, taken five times daily for five days, decreases the pain of the blisters and speeds healing.[9] Famiciclovir, also known as famcyclovir, may be prescribed in very severe cases.[5] There is no evidence that combining oral antivirals and topical antivirals reduces the lifespan of the cold sore more than using one or the other alone would.[8]

Herpes labialis home remedies

There are a number of home remedies for cold sores, but these are mostly effective in reducing discomfort rather than the duration of the infection. Applying Vaseline or aloe vera to the blisters may reduce pain and will cause no harm.[5] Some herbal remedies that may help with relieving the discomfort and/or promoting healing when applied topically are:[10][11]

  • Lemon balm, also known as melissa. Ointments, such as Lomaherpan or LomaProtect contain lemon balm. Alternatively, lemon balm essential oil can be applied directly.
  • Tea tree essential oil, applied to the affected area.

Do not take essential oils internally. If you have sensitive skin, be sure to dilute them in a carrier oil.

Ice can reduce swelling and relieve pain. People with cold sores may also wish to:

  • Avoid acidic or salty foods, as they will cause pain to the blister
  • Avoid touching their mouth or lips
  • Avoid opening the mouth widely, in a way that stretches the lips[3]
  • Avoid shaving the affected area
  • Eat soft, bland foods

Because herpes labialis spreads easily, they may also wish to:

  • Avoid oral sex
  • Avoid kissing anyone
  • Avoid coming into close contact with small children, toddlers, babies and especially newborns
  • Avoid sharing anything that comes into contact with the mouth


Q: Is a herpes simplex infection dangerous if I have a weakened immune system?
A: A herpes simplex infection can be dangerous in some cases. In immunosuppressed or immunocompromised people, the blisters may spread to cover large areas and become very painful. They are not always limited to the mouth and face, but may occur on any mucosal surface including the genitals. Also, there might not be external blisters to indicate an active internal herpes simplex infection. If left untreated, the infection can be fatal.[12] If you are concerned that you may have a weakened immune system, or if your symptoms seem severe, consult the free Ada app for a symptom assessment.

Read more about Herpes Simplex »

Q: Why is an HSV infection serious for babies? A: Herpes simplex infections in very young children, also called neonatal herpes, can be fatal to babies and newborns. The virus spreads to the child’s internal organs and has to be treated with intravenous antiviral drugs. Even so, it is often fatal.[13]

If your child has been exposed to herpes and shows any of the following symptoms, it is advisable to seek medical assistance as soon as possible:

  • Listlessness and abnormal sleepiness
  • Unwillingness to eat
  • Floppiness
  • Fever
  • Breathing difficulties, including grunting, rapid breathing, or blue skin
  • High-pitched crying
  • Skin rash

If you are concerned that your baby may have an HSV infection, consult the Ada app for a symptom assessment.

Q: Does the same virus cause herpes labialis and shingles? A: No. Shingles and cold sores are not caused by the same virus, even though both manifest as painful skin lesions and are the result of a dormant viral infection reactivating. Shingles is caused by varicella zoster, also known as herpes zoster, while herpes labialis is the result of an HSV infection. However, the viruses that cause herpes labialis (HSV-1 and HSV-2) are related to the virus that causes shingles (varicella zoster): all three are subtypes of the Human Herpes Virus. See our resource on signs of shingles for more information.

Other names for herpes labialis

  • Cold sores
  • Herpes simplex labialis
  • Oral herpes
  • Orofacial herpes
  • Orolabial herpes infection

  1. Netdoctor. “Cold sores.”. 12 December 2013. Accessed 9 March 2018.

  2. Canadian Family Physician. “Treatment and prevention of herpes labialis”. December 2008. Accessed 9 March 2018.

  3. NHS Choices. “Cold sores.”. 4 July 2017. Accessed 9 March 2018.

  4. British Skin Foundation. “Impetigo”. Accessed 9 March 2018.

  5. London Doctors Clinic. “The curse of the cold sore”20 March 2017. Accessed 10 March 2018.

  6. How to Get Rid of a Cold Sore. “Cold Sore Stages – Here’s What To Expect From Beginning To End”. 26 January 2017. Accessed 10 March 2018.

  7. American Nurse Today. “Common sense about cold sores”. February 2011. Accessed 9 March 2018.

  8. University of Saskatchewan MedSask. “ Cold Sore - Guidelines for Prescribing Oral Antivirals”. May 2017. Accessed 30 March 2018.

  9. Journal of Family Practice. “What are the best treatments for herpes labialis?”. July 2007. Accessed 9 March 2018.

  10. Herbfacts. “Cold sore alert: natural ways to manage cold sores”. Accessed 30 March 2018.

  11. Herpes Virus Association. “Lomaherpan Cream”. Accessed 30 March 2018.

  12. Pathology, Research and Practice. “Generalized herpes simplex virus infection in an immunocompromised patient--report of a case and review of the literature.”. 2005. Accessed 10 March 2018.

  13. NHS Choices. “Neonatal herpes (herpes in a baby)”. 14 August 2015. Accessed 09 March 2018.