Cold sores are also called fever blisters.
Cold sores is a skin disease caused by herpes simplex virus (HSV) infection. Cold sores usually affect the face, mouth and throat of both men and women. Genital herpes infection is very common, about 80% of the U.S. population has been infected with herpes virus without ever having symptoms or a previous diagnosis. More serious infections can happen when the virus infects the eyes, brain and other internal organs; this is more common in people with weakened immune function.
Within a week of the first herpes infection, the skin starts to have burning, itching or tingling, then groups of pink painful blisters form. The blisters then break open and form small sores that may ooze scant amounts of fluid. The sores then scab and heal over the next 2-6 weeks. When the cold sore is severe, the person may have difficulty eating and drinking. After the first herpes episode, the herpes virus goes to the nearby nerves and stays inactive for months to years. When a person is under stress or has weakened immune functions, the virus wakes up, travels back to the skin and causes a herpes outbreak. The first episode is often more severe, and the person may have fevers, muscle cramps, swollen lymph nodes and headaches. Over time, the outbreaks may become further apart, shorter in length and less severe.
Although they are called “cold sores” and “fever blisters,” you do not need either a cold or a fever to get cold sores. The herpes virus is transmitted when the virus enters the body through small tears in the skin. Cold sores can be transmitted through kissing, oral sex, and other skin-to-skin contact. People who have active herpes are contagious because the blister fluid and scabs can shed the virus. Some carriers of herpes virus are contagious even when they do not have symptoms. Other causes of cold sores include:
- Weakened immune function. People with weakened immune function, such as very young children, seniors, people with diabetes, HIV, or those taking medication that lowers immune function, tend to get herpes infections and outbreaks more easily. The rash may involve a larger skin area and last longer.
- Stress from recent illness, injury, menstruation, as well as emotional stress can weaken one’s immune function and cause a herpes outbreak. Trauma to the area of the initial infection or from tooth extraction can cause nerve pain and herpes outbreaks.
- Ultraviolet light exposure from sunlight or phototherapy treatment for other skin diseases may weaken the immune function on the skin and trigger herpes outbreaks.
- Eczema. Children with eczema have weakened skin protective layers and are at risk of getting herpes infections.
- Athletes who participate in contact sports, such as wrestlers, are at higher risk for getting herpes skin infections because of frequent skin breakage and skin-to-skin contact.
Although there is currently no cure for cold sores, several treatments may help decrease the severity, frequency and length of outbreaks.
- Topical antiviral medication such as topical acyclovir that can be obtained as a prescription from a qualified health professional.
- Topical steroids can be used to reduce the inflammation that results from cold sores and is used in combination with a topical antiviral. Multiple studies have shown that combining a steroid with an antiviral medication is more effective than using the antiviral medication alone.[2,3]
- Antiviral medications: Medications like acyclovir and valacyclovir can be prescribed by a qualified health professional to help reduce the severity and length of a cold sore outbreak (herpes infection). For people who have frequent recurring cold sores, long treatment with antiviral medications can help reduce the number of outbreaks that occur.
- Pain medications: Over-the-counter pain medications such as ibuprofen, acetaminophen, and lidocaine patches may temporarily help with mild to moderate pain from cold sores. For more severe cases, prescription pain medications may be needed and should be discussed with a qualified health professional.
There are some lifestyle changes that can help prevent herpes:
- Avoid sexual contact with anyone who has an active herpes outbreak. However, herpes can still be spread from skin to skin contact even in those that do not appear to have an active outbreak. Condoms do not protect against the spread of herpes.
- Avoid sharing clothing and personal items with anyone who has an active herpes outbreak.
- If you have a herpes outbreak, cover the rash with a bandage or clothing to prevent transmitting the virus to other people.
1. Centers for Disease C, Prevention. Seroprevalence of herpes simplex virus type 2 among persons aged 14-49 years--United States, 2005-2008. MMWR Morb Mortal Wkly Rep.2010;59(15):456-459; PMID: 20414188.
2. Arain N, Paravastu SC, Arain MA. Effectiveness of topical corticosteroids in addition to antiviral therapy in the management of recurrent herpes labialis: a systematic review and meta-analysis. BMC Infect Dis.2015;15:82; PMID: 25887308.
3. Rosa MI, Souza SL, Farias BF, et al. Efficacy of Topical 5% Acyclovir-1% Hydrocortisone Cream (ME-609) for Treatment of Herpes Labialis: a systematic review. An Acad Bras Cienc.2015;87(2 Suppl):1415-1420; PMID: 26247156.