Cold sores are a symptom of an oral herpes infection. They are usually caused by a type of herpes that primarily affects the area around the lips and mouth. These sores are very common and usually go away without treatment. However, the infection that causes cold sores never goes away, so the sores may reappear in the future.
Types of Herpes
Herpes is caused by an infection of one of the two types of herpes simplex virus (HSV):
- Herpes simplex virus type 1 (HSV-1): Usually causes oral herpes, which may lead to the development of cold sores.
- Herpes simplex virus type 2 (HSV-2): Usually causes genital herpes, which may lead to the development of genital sores.
HSV-1 is highly contagious and is spread through saliva or close contact, especially when open sores are present. Oral herpes is typically spread through kissing. Less commonly, it can spread by sharing personal items that have come into contact with the virus, such as:
- Lip balm.
In many cases, HSV-1 can spread to the genitals or HSV-2 can spread to the mouth through oral sex. However, cold sores are most commonly caused by HSV-1.
What Are Cold Sores?
Cold sores (which are also known as fever blisters, mouth ulcers, or herpes labialis) can develop on the lips or around the mouth as a result of an oral herpes infection. Most cold sores appear with about one to three weeks of exposure to the herpes virus. Before a sore develops, other herpes symptoms may include:
- Swollen glands
- Sore throat
- Pain when swallowing
Each cold sore will go through a series of stages:
- Before it appears: A tingling, itching, or slight burning sensation starts to develop in the area about 12 to 24 hours before the cold sore appears. A hard, painful spot begins to grow just under the skin.
- Blistering stage: A red blister filled with a clear, yellowish fluid appears. If it starts out as several smaller blisters, it may grow together into a larger blister.
- Weeping stage: The blisters rupture and begin to ooze the yellowish fluid from inside, forming a sore. This usually occurs about two to three days after the blister appears.
- Crusting stage: After another day or two, the sore crusts over and forms a scab. There may be some cracking or bleeding that occasionally occurs.
- Healing stage: The scab eventually falls off. The skin underneath is usually still a bit pink and tender. This area should be completely healed within about one to two weeks.
Cold Sore Treatment
In most cases, cold sores heal on their own within about two weeks. Keep the area clean by gently washing the skin with antiseptic soap and water. It’s best to avoid touching the area or picking at scabs that form. If you do touch a cold sore, be sure to wash your hands right away to avoid spreading the virus.
The following at-home remedies can alleviate symptoms and assist in healing:
- Apply a cold or warm compress.
- Gargle with cool water.
- Rinse with salt water.
- Take an over-the-counter pain reliever like acetaminophen (Tylenol).
- Wear sunscreen and a lip balm with SPF.
- Avoid acidic and spicy foods.
You can also ask your healthcare provider about antiviral treatments. An antiviral cream or ointment can be applied to relieve symptoms, and certain antiviral pills or shots can be administered to shorten the length of an outbreak. The antiviral medications most commonly prescribed for oral herpes include:
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Complications of cold sores are very rare, but they may include:
- Eye infection: There is a risk of spreading the virus by touching a cold sore and then touching the eyes. This may cause a potentially serious cornea infection called HSV keratitis, which can lead to vision problems or blindness.
- Genital sores: HSV-1 can be spread through oral sex. This may cause sores to develop on or around the genitals.
- Newborn health issues: Babies under 6 months old are at risk for seizures and high fever if they become infected with HSV-1.
The risk of developing cold sore complications is highest among people who are immunocompromised, such as those with the following medical conditions or treatments:
- Severe burns.
- Chemotherapy for cancer.
- Anti-rejection medication for an organ transplant.
Cold Sore Recurrence
Once you have the oral herpes virus, it will never go away. After an initial outbreak, the virus typically remains dormant most of the time. However, the virus can be triggered by a number of factors, which may cause more cold sores to develop.
Some of the factors which may cause cold sores to keep coming back include:
- Cracked, sunburned or dry lips.
- Exposure to harsh winds or sunlight.
- Emotional or physical stress.
- Fever, viral infection, or illness, such as a cold or the flu.
- Menstruation, pregnancy, or other hormonal changes.
Some people with HSV-1 get cold sores often, while others get them only rarely or not at all. Most people find that the frequency of their outbreaks decreases over time after the initial infection.
Herpes and Cold Sore Prevention
If you do not currently have herpes, you can help to prevent it by using the following tips:
- Avoid intimate contact, including kissing, with anyone who has a cold sore.
- Avoid performing oral sex on someone who has genital sores.
- Don’t share any of the following items with someone who has a cold sore:
- Lip balm.
If you have a herpes infection and want to avoid future outbreaks, use these tips for preventing cold sores:
- Protect your lips with an SPF lip balm and wear sunscreen.
- Get enough rest to avoid fatigue.
- Try to stay healthy and avoid stress.
Be sure to wash your hands frequently and avoid intimate contact if you’re currently experiencing an outbreak to prevent the spread of the virus to others.
Oral Herpes by the Numbers
You might be surprised to learn just how common cold sores are. Check out the following oral herpes statistics:
- Approximately 3.7 billion people under age 50 have HSV-1 globally.
- Around 40% to 50% of adults in the U.S. have oral herpes.
- The highest rates of infection occur in Africa, where about 87% of people have HSV-1.
Herpes – oral, MedlinePlus, November 2019.