Cold sores

Cold sores, also known as fever blisters, are blister-like sores that usually develop on the outer edge of the lip.


Causes/associated factors
Cold sores are caused by the herpes simplex virus, one of six types of herpes viruses that can cause disease in humans. Herpes simplex virus type 1 is typically to blame. Herpes simplex virus type 2 can also cause cold sores, but it more commonly causes genital sores.
The herpes simplex virus is usually contracted during childhood. After an initially mild or even unrecognized infection, the virus becomes dormant (remains inactive inside your nerve cells). It can emerge years later on or near the original site of infection. This re-emergence can be triggered by a weak immune system, trauma, illness, dental work, fever, stress, fatigue, dietary changes, menstruation or other hormonal changes. Ultraviolet light is another common trigger for these recurrences. The severity of the outbreak is often proportional to the degree of sunlight exposure.


Transmission
The first outbreak is the most infectious because the virus is present in the greatest quantities and the lesions tend to last longer. Cold sores are highly contagious from the time the blisters break until the sores heal. The incubation period following the initial exposure (time from exposure until symptoms appear, if they appear at all) is typically two to 12 days.
The herpes simplex virus usually spreads through direct contact with a lesion, such as through kissing, oral/genital or oral/anal contact. It can also spread through indirect contact, such as drinking out of the same cup, using the same eating utensils or sharing lipsticks. Health care professionals, particularly dental workers, must be especially careful because they can contract the virus on their fingers. This causes a condition known as herpetic whitlow.

When you have a cold sore, you can spread the disease to your eye by touching your lip and then carrying the virus on your finger to your eye. This process is called autoinoculation. To prevent infecting your eyes, wash your hands often and avoid touching your eyes when you have a cold sore.


Signs/symptoms
The initial infection often has no symptoms. If symptoms appear, you may notice fever, swollen neck glands and general aching with small blisters in the mouth. The blisters will appear eroded and covered with a white film. The erosions may spread to the tongue, roof of the mouth or tonsils. They may cause pain or bad breath or interfere with eating. These initial symptoms typically last 10 to 14 days.
Recurring cold sores typically appear as small groups of blisters with a red base on the outer edge of the lip, but they may appear on the gums or hard palate of the mouth. (This helps differentiate them from canker sores, which don't develop on hard surfaces such as the gums or hard palate.) Less commonly, cold sores may affect the cheeks, eyelids or earlobes. Once the blisters form crusts, complete healing takes eight to 10 days. How often the cold sores recur varies. Some outbreaks will be mild and others more severe. You may notice heightened sensitivity, pain or an itchy feeling at the site up to 24 hours before a recurrence, during what's called the prodromal phase.


Diagnosis
Your doctor will ask questions about your medical history and do a physical exam. The diagnosis is usually made with only a visual inspection, but an analysis of a sample of the material from the cold sore or a blood test may be done to confirm the presence of the herpes simplex virus.

Treatment
There's no cure for cold sores. Most people don't need treatment with antiviral medications. Left untreated, they normally heal within two weeks. To relieve pain and speed recovery, however, your doctor may suggest the following self-care measures. Typically, treatment is most effective when started within the first 48 to 72 hours.
Apply ice to the affected area during the first 24 hours after the sore appears.

Avoid spicy or acidic foods, such as tomatoes, citrus and pineapple. Instead, eat soft, bland foods to avoid irritating your sores and causing additional pain.

Try an over-the-counter medication recommended by a pharmacist specifically for cold sores. Docosanol (Abreva, for example) is a nonprescription topical medication for cold sores.

Penciclovir cream (Denavir, for example) or acyclovir cream (Zovirax, for example), both available by prescription, may also be effective.

Oral antiviral medications such as acyclovir (Zovirax, for example) famciclovir (Famvir, for example) or valacyclovir (Valtrex, for example)may be prescribed to lessen the severity of cold sore attacks or prevent future outbreaks. If you have a weak immune system or a severe case, contact your doctor. You may be given intravenous acyclovir.

Topical steroid creams may be recommended along with oral antiviral medications. However, use these only if recommended by your doctor.
If you have a cold sore near your eye or one that takes more than three weeks to heal, consult your doctor.


Complications
Most people recover from cold sores without complications. However, cold sores can lead to blindness if the eyes are involved. In fact, herpes simplex infections are a leading cause of blindness in the United States.
Those who have a chronically weak immune system, such as people who are infected with HIV, may have severe and prolonged outbreaks. In this case, consult your doctor as soon as you notice early symptoms of cold sores.

Rarely, viral meningitis (inflammation of the lining of the brain and spinal cord) may develop. Symptoms include headache and nausea. This type of meningitis usually responds well to treatment with intravenous acyclovir. Most people have a complete recovery. In other rare cases, encephalitis (inflammation of the brain) can develop after an infection with herpes simplex virus type I. Even with aggressive medical treatment, this complication can be serious.

If you have a cold sore, avoid contact with anyone in a high-risk group, including:

infants
anyone who has atopic dermatitis (inflammation of the upper layers of skin)
anyone who has a weak immune system (including those who have AIDS, are being treated with chemotherapy or radiation therapy, or are taking immune suppression medication after an organ transplant)
Intense, sharp pain at the site of the lesions or elsewhere along the nerve pathway can last long after the visible lesions have disappeared. This pain may be difficult to diagnose or treat unless you tell your doctor about your history of cold sores.


Pregnancy-specific information
If you're pregnant and have active cold sores, practice strict personal hygiene to prevent spreading the virus to your genital area, which could lead to genital herpes. Genital herpes can spread to the baby during childbirth and cause permanent neurological impairment. Always check with your doctor before using any over-the-counter medications.

Senior-specific information
Older adults may be at greater risk for a recurrence of cold sores due to immunosuppressive medications or treatments. Consult your doctor if you have any unusual sores in or near your mouth.

Prevention
To prevent cold sores, practice good personal hygiene and avoid direct contact with anyone who has a cold sore. If you work in the health care field, wear gloves when caring for patients who have open sores.
If you have a cold sore, thoroughly wash your hands after you touch the sore and before you touch any other part of your body -- especially your eyes. Avoid sharing toothbrushes, lipstick, towels, food, drinks, utensils and shaving items. It's also important to avoid intimate contact, including kissing, oral/genital and oral/anal contact while the sore is present. If you notice a child with a cold sore putting toys in his or her mouth, make sure the toys aren't shared with others. Wash the toys thoroughly as soon as possible.

To prevent recurrences, avoid known triggers whenever possible. If your cold sores are triggered by sunlight, wear zinc or a sunscreen of SPF 15 or higher on your lips and areas where you tend to have recurrences. This is especially important when you're skiing, swimming, boating or enjoying other outdoor snow or water activities.

If you have a history of recurrences and know you'll be exposed to a trigger, ask your doctor about taking acyclovir 24 hours in advance to help prevent a recurrence. You may also want to consider preventive acyclovir before dental procedures or facial cosmetic procedures such as dermabrasion, laser resurfacing or chemical peels.