cold sores

What are cold sores

Cold sores also called fever blisters, are caused by a contagious virus called herpes simplex virus (HSV). Cold sores are tiny, fluid-filled blisters on and around your lips. These blisters are often grouped together in patches. After the blisters break, a crust forms over the resulting sore. Cold sores usually heal in two to four weeks without leaving a scar. There are two types of herpes simplex virus. Type 1 herpes simplex virus (HSV-1) usually causes oral herpes, or cold sores. Type 1 herpes virus infects more than half of the U.S. population by the time they reach their 20s. Type 2 herpes simplex virus (HSV-2) usually affects the genital area.

Herpes simplex is caused by one of two types of herpes simplex virus (HSV), members of the Herpesvirales family of double-stranded DNA viruses.

  • Type 1 herpes simplex virus is mainly associated with oral and facial infections
  • Type 2 herpes simplex virus is mainly associated with genital and rectal infections (anogenital herpes)

However, either virus can affect almost any area of skin or mucous membrane.

After the primary episode of infection, herpes simplex virus (HSV) resides in a latent state in spinal dorsal root nerves that supply sensation to the skin. During a recurrence, the virus follows the nerves onto the skin or mucous membranes, where it multiplies, causing the clinical lesion. After each attack and lifelong, it enters the resting state.

During an attack, the herpes simplex virus (HSV) can be inoculated into new sites of skin, which can then develop blisters as well as the original site of infection.

Some people have no symptoms from the infection. But others develop painful and unsightly cold sores. Cold sores usually occur outside the mouth, on or around the lips. When they are inside the mouth, they are usually on the gums or the roof of the mouth. They are not the same as canker sores, which are not contagious.

There is no cure for cold sores. They normally go away on their own in a few weeks. Antiviral medicines can help them heal faster. They can also help to prevent cold sores in people who often get them. Other medicines can help with the pain and discomfort of the sores. These include ointments that numb the blisters, soften the crusts of the sores, or dry them out. Protecting your lips from the sun with sunblock lip balm can also help.

When to see a doctor

Cold sores generally clear up without treatment. See your doctor if:

  • You have a weakened immune system
  • The cold sores don’t heal within two weeks
  • Symptoms are severe
  • You have frequent recurrences of cold sores
  • You experience irritation in your eyes

Figure 1. Cold sores

cold sores

Are cold sores herpes?

Yes. Cold sores are caused by herpes simplex virus (HSV). There are two types of herpes simplex virus. Type 1 herpes simplex virus (HSV-1) usually causes oral herpes, or cold sores. Type 1 herpes virus infects more than half of the U.S. population by the time they reach their 20s. Type 2 herpes simplex virus (HSV-2) usually affects the genital area.

How do you get cold sores?

Primary attacks of type 1 herpes simplex virus (HSV-1) infections occur mainly in infants and young children. In crowded, underdeveloped areas of the world, nearly all children have been infected by the age of 5. In less crowded places, the incidence is lower; for example, less than half of university entrants in Britain have been infected. Type 2 herpes simplex virus (HSV-2) infections occur mainly after puberty and are often transmitted sexually.

Herpes simplex virus (HSV) is transmitted by direct or indirect contact with someone with active herpes simplex, which is infectious for 7–12 days. Asymptomatic shedding of the virus in saliva or genital secretions can also lead to transmission of herpes simplex virus (HSV), but this is infrequent, as the amount shed from inactive lesions is 100 to 1000 times less than when it is active. The incubation period is 2–12 days.

Minor injury helps inoculate herpes simplex virus (HSV) into the skin. For example:

  • A thumb sucker may transmit the virus from their mouth to their thumb.
  • A health-care worker may develop herpetic whitlow (paronychia)
  • A rugby player may get a cluster of blisters on one cheek (‘scrumpox’).

Are cold sores contagious?

Yes. Cold sores are contagious even if you don’t see the sores. Cold sores are spread from person to person by close contact, such as kissing. Cold sores are caused by a herpes simplex virus (HSV-1) closely related to the one that causes genital herpes (HSV-2). Both of these viruses can affect your mouth or genitals and can be spread by oral sex.

Can you get genital herpes from a cold sore?

Yes — it is possible to get genital herpes from oral sex.

Genital herpes is caused by the herpes simplex virus (HSV). There are two types of herpes viruses — HSV-1 and HSV-2. Genital herpes is usually caused by HSV-2; oral herpes (cold sores) is usually caused by HSV-1.

However, genital herpes can also be caused by HSV-1. Someone with HSV-1 can transmit the virus through oral contact with another person’s genitals, anus, or mouth, even if they don’t have sores that are visible at the time.

Other than abstinence (not having sex) the best way to help prevent herpes is to use a condom during any type of sex (oral, vaginal, or anal). Girls should have their partners use a dental dam every time they receive oral sex to help protect against genital herpes. And if either partner has a sore, it’s best to not have sex until the sore has cleared up.

How long do cold sores last?

Cold sores usually heal in two to four weeks without leaving a scar.

There’s no cure for herpes simplex virus (HSV) infection, and the blisters may return. Antiviral medications can help cold sores heal more quickly and may reduce how often they return.

What causes cold sores

Cold sores are caused by certain strains of the herpes simplex virus (HSV). Type 1 herpes simplex virus (HSV-1) usually causes cold sores. Type 2 herpes simplex virus (HSV-2) is usually responsible for genital herpes. However, either type can cause sores in the facial area or on the genitals. Most people who are infected with the virus that causes cold sores never develop signs and symptoms.

Cold sores are most contagious when oozing blisters are present. But you can transmit the virus to others even if you don’t have blisters. Shared eating utensils, razors and towels, as well as kissing, may spread HSV-1. Oral sex can spread HSV-1 to the genitals and HSV-2 to the lips.

Once you’ve had an episode of herpes infection, the virus lies dormant in nerve cells in your skin and may emerge as another cold sore at the same place as before. Recurrence may be triggered by:

  • Viral infection or fever
  • Hormonal changes, such as those related to menstruation
  • Stress
  • Fatigue
  • Exposure to sunlight and wind
  • Changes in the immune system

Risk factors for getting cold sores

About 90 percent of adults worldwide — even those who’ve never had symptoms of an infection — test positive for evidence of the herpes simplex virus (HSV) that causes cold sores.

People who have weakened immune systems are at higher risk of complications from the herpes simplex virus (HSV). Medical conditions and treatments that increase your risk of complications include:

  • Severe burns
  • Eczema
  • Cancer chemotherapy
  • Anti-rejection drugs for organ transplants

How to prevent cold sores

Sun exposure often triggers facial herpes simplex, sun protection using high protection factor sunscreens and other measures are important.

Your doctor may prescribe an antiviral medication for you to take on a regular basis, if you develop cold sores frequently or if you’re at high risk of serious complications. Antiviral drugs will stop herpes simplex virus (HSV) multiplying once it reaches the skin or mucous membranes but cannot eradicate the virus from its resting stage within the nerve cells. They can, therefore, shorten and prevent attacks but a single course cannot prevent future attacks. Repeated courses may be prescribed, or the medication may be taken continuously to prevent frequent attacks.

To help avoid spreading cold sores to other people or to other parts of your body, you might try some of the following precautions:

  • Avoid skin-to-skin contact with others while blisters are present. The virus spreads most easily when there are moist secretions from the blisters.
  • Avoid sharing items. Utensils, towels, lip balm and other items can spread the virus when blisters are present.
  • Keep your hands clean. When you have a cold sore, wash your hands carefully before touching yourself and other people, especially babies.

Cold sores symptoms

A cold sore usually passes through several stages:

  • Tingling and itching. Many people feel an itching, burning or tingling sensation around their lips for a day or so before a small, hard, painful spot appears and blisters erupt.
  • Blisters. Small fluid-filled blisters typically break out along the border where the outside edge of the lips meets the skin of the face. Cold sores can also occur around the nose or on the cheeks.
  • Oozing and crusting. The small blisters may merge and then burst, leaving shallow open sores that will ooze fluid and then crust over.

Cold sore signs and symptoms vary, depending on whether this is your first outbreak or a recurrence. Cold sores can last several days, and the blisters can take two to four weeks to heal completely. Recurrences typically appear at the same spot each time and tend to be less severe than the first outbreak.

During first-time outbreaks, some people also experience:

  • Fever
  • Painful eroded gums
  • Sore throat
  • Headache
  • Muscle aches
  • Swollen lymph nodes

Children under 5 years old may have cold sores inside their mouths and the lesions are commonly mistaken for canker sores. Canker sores involve only the mucous membrane and aren’t caused by the herpes simplex virus.

Primary herpes simplex

Primary infection with herpes simplex virus (HSV) can be mild or subclinical, but symptomatic infection tends to be more severe than recurrences. Type 2 herpes simplex virus (HSV-2) is more often symptomatic than type 1 herpes simplex virus (HSV-1).

Primary type 1 herpes simplex virus (HSV-1) most often presents as gingivostomatitis (inflammation of the gums and lips caused by the herpes virus), in children between 1 and 5 years of age. Symptoms include fever, which may be high, restlessness and excessive dribbling. Drinking and eating are painful, and the breath is foul. The gums are swollen and red and bleed easily. Whitish vesicles evolve to yellowish ulcers on the tongue, throat, palate and inside the cheeks. Local lymph glands are enlarged and tender.

The fever subsides after 3–5 days and recovery is usually complete within 2 weeks.

Primary type 2 herpes simplex virus (HSV-2) usually presents as genital herpes after the onset of sexual activity. Painful vesicles, ulcers, redness and swelling last for 2 to 3 weeks, if untreated, and are often accompanied by fever and tender inguinal lymphadenopathy.

In males, herpes most often affects the glans, foreskin and shaft of the penis. Anal herpes is more common in males who have sex with men than with heterosexual partners.

In females, herpes most often arises on the vulva and in the vagina. It is often painful or difficult to pass urine. Infection of the cervix may progress to severe ulceration.

Recurrent herpes simplex

After the initial infection, whether symptomatic or not, there may be no further clinical manifestations throughout life. Where viral immunity is insufficient, recurrent infections are common, particularly with type 2 herpes simplex virus (HSV-2) genital herpes.

Recurrences can be triggered by:

  • Minor trauma, surgery or procedures to the affected area
  • Upper respiratory tract infections
  • Sun exposure
  • Hormonal factors (in women, flares are not uncommon prior to menstruation)
  • Emotional stress

In many cases, no reason for the eruption is evident.

The vesicles tend to be smaller and more closely grouped in recurrent herpes, compared to primary herpes. They usually return to roughly the same site as the primary infection.

  • Recurrent type 1 herpes simplex virus (HSV-1) can occur on any site, most frequently the face, particularly the lips (herpes simplex labialis).
  • Recurrent type 2 herpes simplex virus (HSV-2) may also occur on any site, but most often affects the genitals or buttocks.

Itching or burning is followed an hour or two later by an irregular cluster of small, closely grouped, often umbilicated vesicles on a red base. They normally heal in 7–10 days without scarring. The affected person may feel well or suffer from fever, pain and have enlarged local lymph nodes.

Herpetic vesicles are sometimes arranged in a line rather like shingles and are said to have a zosteriform distribution, particularly when affecting the lower chest or lumbar region.

White patches or scars may occur at the site of recurrent herpes simplex virus (HSV) attacks and are more evident in those with the skin of color.

Cold sores complications

In some people, herpes simplex virus (HSV) that causes cold sores can cause problems in other areas of the body, including:

Eye infection

Herpes simplex may cause swollen eyelids and conjunctivitis with opacity and superficial ulceration of the cornea (dendritic ulcer, best seen after fluorescein staining of the cornea).

Throat infection

Throat infections may be very painful and interfere with swallowing.

Eczema herpeticum

In patients with a history of atopic dermatitis or Darier disease, herpes simplex virus (HSV) may result in severe and widespread infection, known as eczema herpeticum. The skin disease can be active or historical. Numerous blisters erupt on the face or elsewhere, associated with swollen lymph glands and fever.

Erythema multiforme

A single episode or recurrent erythema multiforme is an uncommon reaction to herpes simplex. The rash of erythema multiforme appears as symmetrical plaques on hands, forearms, feet and lower legs. It is characterized by target lesions, which sometimes have central blisters. Mucosal lesions may be observed.

Nervous system

Cranial/facial nerves may be infected by herpes simplex virus (HSV), producing temporary paralysis of the affected muscles. Rarely, neuralgic pain may precede each recurrence of herpes by 1 or 2 days (Maurice syndrome). Meningitis is rare.

Widespread infection

Disseminated infection and/or persistent ulceration due to herpes simplex virus (HSV) can be serious in debilitated or immune deficient patients, for example in people with human immunodeficiency virus (HIV) infection.

Cold sores diagnosis

Your doctor can usually diagnose cold sores just by looking at them. To confirm the diagnosis, he or she may take a sample from the blister for testing in a laboratory by culture or PCR of a viral swab taken from fresh vesicles. Herpes simplex virus (HSV) serology is not very informative, as it’s positive in most individuals and thus not specific for the lesion with which they present.

Cold sores treatment

Cold sores generally clear up without treatment in two to four weeks. Blisters may be covered if desired, for example with a hydrocolloid patch. Severe infection may require treatment with an antiviral agent.

Several types of prescription antiviral drugs may speed the healing process. Examples include:

  • Acyclovir (Xerese, Zovirax) – 200 mg 5 times daily for five days
  • Valacyclovir (Valtrex) – 1 g 3 times daily for seven days
  • Famciclovir (Famvir) – as a single dose of 3 x 500 mg
  • Penciclovir (Denavir)

Some of these products are packaged as pills to be swallowed. Others are creams to be applied to the sores several times a day. In general, the pills work better than the creams. For very severe infections, some antiviral drugs can be given with an injection.

Topical aciclovir or penciclovir may shorten attacks of recurrent herpes simplex, provided the cream is started early enough.

Higher doses of antiviral drugs are used for eczema herpeticum or for disseminated herpes simplex.

Home remedies for cold sores

The over-the-counter cold sore ointment docosanol (Abreva) may shorten the healing time of a cold sore. At the first sign of symptoms, apply it to the affected skin as directed on the package.

To ease the discomfort of a cold sore:

  • Try other cold sore remedies. Some over-the-counter preparations contain a drying agent, such as alcohol, that may speed healing.
  • Use lip balms and cream. Protect your lips from the sun with a zinc oxide cream or lip balm with sunblock. If your lips become dry, apply a moisturizing cream.
  • Apply a cool compress. A cool, damp cloth may reduce redness, help remove crusting and promote healing.
  • Apply pain-relieving creams. Over-the-counter creams with lidocaine or benzocaine may offer some pain relief.

Alternative medicine

Although study results have been mixed, alternative medicine treatments for cold sores include:

  • Lysine. An amino acid, lysine is available as an oral supplement and as a cream.
  • Propolis. Also known as synthetic beeswax, this is available as a 3 percent ointment. When applied early and often, it may shorten the duration of the breakout.
  • Rhubarb and sage. A cream combining rhubarb and sage may be about as effective as acyclovir (Zovirax) cream.
  • Stress reduction. If your cold sores are triggered by stress, you might want to try relaxation techniques, such as deep-breathing exercises and meditation.