Cold sores: Symptoms, Causes, Treatment & Prevention

What are Cold Sores?

Herpes labialis (cold sores) is a viral infection that is caused by Herpes simplex virus, type 1 Herpes viruses are double-stranded DNA viruses.

They relate to the types Herpesviridae. Herpesviridae contains 8 types of herpes viruses that cause various diseases in humans.


Cold sores (herpes labialis) is caused by the human herpesvirus type 1 – Herpes simplex virus type 1 (HSV 1).

The virus belongs to the group of alpha-herpesviruses. They have a rapid replication and broad range of people affected. After getting infected, just like with other herpes viruses, they persist in a latent state in neuronal ganglia (a structure containing a number of nerve cell bodies, typically linked by synapses, and often forming a swelling on a nerve fiber) [2]. Therefore, about 30% of all infected people suffer from recurrent herpes infections.

What are the clinical alterations caused by the virus?

Infection with the virus is airborne. Herpes virus enters through mucous membranes or through a break in the skin and begins to multiply in the around and inside the mouth. On the surface of nerve fibers, the virus moves on to the sensory ganglia. Even after the infection has resolved, the virus remains dormant in the sensory ganglia and can be reactivated under certain conditions, leading to a new manifestation of the virus. The virus can be activated by various factors – stress, other infection, immunosuppression, fever, cold, heat and many others.
Depending on its’ localization, herpes virus type 1 causes:

  • Gingivostomatitis herpetic – herpes gingivostomatitis (inflammation of the gums and oral mucosa;
  • Herpes labialis – herpes labial (lips);
  • Herpes nasalis – nasal herpes;
  • Herpes genitalis – genital herpes (herpes virus type 1 and 2 can cause both labial and genital herpes. In most cases, type 1 causes the occurrence of herpes in the upper half of the body and type 2 – at the bottom);
  • Herpes perianalis / glutealis – perianal / gluteal (around the gluteal area) herpes;
  • Herpes facialis / buccalis – facial / buccal (on the face and cheeks) herpes.

What are the symptoms?

The incubation period is around a week. When the oral mucosa is being infected, blisters with clear content (vesicles) are formed. The skin around the blisters is often red, swollen, and sore. The blisters may break open, leak a clear fluid, and then scab over after a few days. Patients often complain of severe pain, unpleasant breath (foetor ex-ore), dysphagia (swallowing problems) [1]. The overall condition is deteriorated, there may be symptoms such as fever, fatigue, inflamed regional lymph nodes – but children are more prone to experience such symptoms. Once the blisters have dried and crusted over (within a few days), the risk of contagion is significantly lessened.

Herpes Labialis
Figure 0003: Herpes labialis with oral erosions

However, a person infected with HSV can pass it on to another person even when a cold sore is not present. This is because the virus is sometimes shed in saliva even when sores are not present.
The condition must be distinguished from acute eczema and herpes zoster. Clinical features, anamnesis and the experience of the specialist would properly identify the exact disease that has affected you.
Herpes infections, regardless of where they originally appeared, tend to reappear (usually affecting the same areas). These recurrences may occur frequently (eg several times a year) or only occasionally (e.g. once or twice a year).

After the first infection, the virus enters the nerve cells and travels along the nerves until it reaches a place called a nerve ganglion ( a small cystic tumor connected either with a joint membrane or tendon sheath). There it settles quietly in the stage, which is referred to as “passive” or “latentnen.” Occasionally, the virus can become active and start again to reproduce and cause sores and blisters. The exact mechanism is not completely understood yet, but there are some conditions that are associated with it. These conditions include:

  • Fever, cold or flu;
  • UV radiation (sun exposure);
  • Stress;
  • Changes in the immune system;
  •  Trauma in the affected area;
  • Sometimes there is no apparent reason for recurrence;

When cold sores affect the genitals, patients should be examined for any other sexually transmitted infections. HSV-2 and HSV-1 affect the genitals, pubic area, buttocks, back of the thigh or inner thigh. Herpes can also occur in other parts of the body, although this is less common. On the fingers, it is known as herpes whitlow. 80% of those with genital herpes do not know they have it, as they may have no or very mild herpes symptoms.
Sometimes, the virus infects the body without causing any symptoms. The immune system reacts by starting to produce antibodies against the virus herpes. This response helps infections to heal more easily. With the help of the antibodies, the virus struggles to settle elsewhere in the body. (Otherwise, herpes would spread to other body parts e.g. after washing the face). Thanks to the antibodies, the immune system blocks further spreading of cold sores.


The diagnosis of herpes is usually based solely on the appearance of the lesions. Rarely, further tests are needed to help diagnose herpes.

Scraping the blisters in an attempt to cultivate the virus in a laboratory, can be successfully only during the first 48 hours and before the blisters crust.

Blood tests are often ineffective because the presence of antibodies to herpes means that the body has been exposed to the virus at some point in the past.
If the diagnosis is doubtful, the best approach is to encourage a visit to a doctor right after you have experienced the first signs of pain.

How to cope better with the infection?

Frequent hand washing will help reduce the eventual spreading of the virus to other parts of the body or to other people. Also, the application of cold and moist compresses onto the lesion, may reduce the pain and prevent its’ drying and crack.


For the time being, there are currently no drugs nor vaccines for herpes simplex virus. However, if you avoid triggers such as sunburn and stress, you can help prevent the development of further outbreaks. There are treatments developed to help reduce the time of treatment, the pain associated with the lesion (and in more specific cases, lead to suppression of the recurrence of the virus).

Home treatment

Tea tree

Tea tree [4] is known for its antiviral and anti-inflammatory properties (Melaleuca alternifoliate). It offers fast and effective treatment of painful vesicles in herpes.
Dilute the tea tree oil with water in proportion 1:3. Soak a cotton pad soaked in the solution, apply it on the affected area several times. Herpes will heal completely in a few days.

Pine-needle oil

Pine needle oil strengthens the immune system, influences the nervous system, calms after stress and is widely used in home remedies as a treatment for cold sores. In order to get rid of cold sores, The infected area should be treated with a cotton pad soaked in pine oil. This may cause burning sensation on the lips. Apply the oil very gently and try not to contact mucous areas.

Warning: This treatment is not recommended for pregnant women and people suffering from ulcers or kidney disease.

Essential lemon oil

It has been proven that essential lemon oil [7] heals and dries up cold sores. Add a very small dab directly to the cold sore. Also, try diluting it with coconut oil and using it as a lip balm to prevent cold sores during common times of flare up.

Rubbing Alcohol

Although alcohol works best with bacteria, it’s been noted to work with the virus causing cold sores. Just apply it on the skin several times a day, making sure that it dries out on its own before reapplication.

Alcohol is able to the lifespan of the cold sore, even as it prevents further complications due to bacterial infestation. Make sure you’re using 70% alcohol as it is the best level of concentration to apply to a cold sore.

Aloe Vera

“A natural substance can be just as effective, and possibly safer than prescribed pharmacologic remedies,” says J. Michael Adame, DDS, FAGD, a former pharmacist, and spokesperson for the Academy of General Dentistry. Dr. Adame recommends that cold sore sufferers apply aloe vera [3] lip balm three times per day until the lesion has dried. “It will combat the sore and enhance healing,” he says.

Peppermint Oil

In test tubes, peppermint oil [6] has stopped a number of viruses from reproducing, including herpes. However, it is not known whether peppermint oil, applied topically, would have any effect on the herpes virus in humans.

Zinc Oxide

In one small study, people who applied zinc oxide [5] cream to cold sores saw them heal faster than those who applied a placebo cream. In another study, people who used a proprietary topical formulation with zinc oxide, l-lysine, and 14 other ingredients saw a decrease in symptoms and duration of lesions. High doses of zinc can be dangerous. Zinc may interact with some antibiotics and with cisplatin, a chemotherapy drug.

In another study, people who used a proprietary topical formulation with zinc oxide, l-lysine, and 14 other ingredients saw a decrease in symptoms and duration of lesions. High doses of zinc can be dangerous. Zinc may interact with some antibiotics and with cisplatin, a chemotherapy drug.


L-Lysine [8] is an essential amino acid, meaning it is necessary for human health, but the body cannot make it.Some studies suggest that taking lysine on a regular basis may help prevent outbreaks of cold sores and genital herpes. L-Lysine appears to be an effective agent for reduction of occurrence, severity and healing time for recurrent HSV infection.

„Lysine has literally saved me from a cold sore meltdown that was taking hold of me.”

Baking Soda [9]: Study has concluded that orally ingested, thereby eliminating soreness caused by the cold sore and curing the cold sore. The carbonate salt may be ingested by any suitable manner such as a tablet, capsule, powder or in an aqueous solution.

Over the counter treatment

The market offers multiple cold sore treatment options, aiming to reduce the healing time and prevent further herpes breakouts. We have collected several products, recommended by patients who successfully managed to make the infection disappear within a short period of time.


    Dysphagia (swallowing problems)
    Definition of ganglion in English
    Aloe vera – An Update for Dentistry
    Melaleuca alternifolia (tea tree) oil gel (6%) for the treatment of recurrent herpes labialis
    A randomized clinical trial on the treatment of oral herpes with topical zinc oxide/glycine.
    Virucidal effect of peppermint oil on the enveloped viruses herpes simplex virus type 1 and type 2 in vitro.
    Absorbable solid compositions for topical treatment of oral mucosal disorders
    Subjective response to lysine in the therapy of herpes simplex
    Oral manifestations of her
Cold sores: Symptoms, Causes, Treatment & Prevention
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Cold sores: Symptoms, Causes, Treatment & Prevention
Herpes labialis (cold sores) is a viral infection that is caused by Herpes simplex virus, type 1 Herpes viruses are double-stranded DNA viruses.
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About the author

Monika Hristova

Monika is the Editor-in-Chief at SkinPractice. She is a skin care addict and researcher, who feels strongly about helping people with different dermatology conditions from alopecia to warts.

You can read her recommendations and advice both here at SkinPractice or at Quora where she answers skincare-related questions frequently and is the most viewed author in the Skincare category with more than 3 million views or follow her on LinkedIn.

She is also a certified skin care specialist with certification from the Medical College in Sofia.

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