Cold sores are red, fluid-filled blisters that form near the mouth or on other areas of the face. In rare cases, cold sores may appear on the fingers, nose, or inside the mouth. They are usually clumped together in patches. Cold sores may persist for two weeks or longer.
A common virus called herpes simplex causes cold sores. They can spread from person to person through close contact, such as kissing. The sores are contagious even when they aren’t visible.
There’s no cure for cold sores, and they may return without warning. Certain medications can be used to treat cold sores and prevent them from coming back.
Cold sores are caused by the herpes simplex virus. There are two types of the herpes simplex virus. The herpes simplex type 1 virus (HSV-1) usually causes cold sores, and the herpes simplex type 2 virus (HSV-2) usually causes genital herpes. The actual sores are similar in appearance for both forms of the virus. It’s also possible for HSV-1 to cause sores on the genitals and for HSV-2 to cause sores on the mouth.
Visible cold sores are contagious, but they may be spread even when they can’t be seen. You can get the herpes simplex virus by coming in contact with infected individuals. This may happen through kissing, sharing cosmetics, or sharing food. Oral sex may spread both cold sores and genital herpes.
Once you get the herpes simplex virus, it can’t be cured but it can be managed. Once the sores have healed, the virus remains dormant in your body. This means that new sores can appear at any time when the virus reactivates. Some people with the virus report more frequent outbreaks when their immune systems are weak, such as during illness or times of stress.
You may notice a tingling or burning sensation on your lips or face several days before a cold sore develops. This is the best time to start treatment. Once the sore forms, you’ll see a raised, red blister full of fluid. It will usually be painful and tender to the touch. There may be more than one sore present.
The cold sore will remain for up to two weeks and will be contagious until it crusts over. Your first cold sore may not appear for up to 20 days after you contract the herpes simplex virus.
You may also experience one or more of the following symptoms during an outbreak:
- muscle aches
- swollen lymph nodes
You should call your doctor immediately if you develop any eye symptoms during a cold sore outbreak. Infections caused by the herpes simplex virus can lead to permanent vision loss when they’re not treated promptly.
A cold sore goes through five stages:
- Stage one: Tingling and itching occurs about 24 hours before blisters erupt.
- Stage two: Fluid-filled blisters appear.
- Stage three: The blisters burst, ooze, and form painful sores.
- Stage four: The sores dry out and scab over causing itching and cracking.
- Stage five: The scab falls off and the cold sore heals.
According to the Mayo Clinic, 90 percent of adults worldwide test positive for the herpes simplex type 1 virus. Once you have the virus, certain risk factors may reactivate it such as:
- infection, fever, or a cold
- sun exposure
- HIV/AIDS or a weakened immune system
- severe burns
- dental work
You’re at risk of getting a cold sore if you come in contact with the fluid of a cold sore through kissing, sharing foods or drinks, or sharing personal care items such as toothbrushes and razors. If you come in contact with the saliva of someone who has the virus, you can get the virus, even if there are no visible blisters.
The initial infection of herpes simplex can cause more severe symptoms and complications, as your body hasn’t built up a defense to the virus yet. Complications are rare, but can occur, especially in young children. Call your doctor immediately if you’re experiencing any of the following symptoms:
- high or persistent fever
- difficulty breathing or swallowing
- red, irritated eyes with or without discharge
Complications are more likely to occur in people who have eczema or a condition that weakens their immune system, such as cancer or AIDS. If you do have any of these conditions, contact your doctor if you think you’ve contracted the herpes simplex virus.
There’s no cure for cold sores, but some people with the herpes simplex virus rarely have outbreaks. When cold sores do develop, there are several ways to treat them.
Ointments and creams
When cold sores become bothersome, you may be able to control pain and promote healing with antiviral ointments, such as penciclovir (Denavir). Ointments tend to be most effective if they’re applied as soon as first signs of a sore appear. They will need to be applied four to five times per day for four to five days.
Docosanol (Abreva) is another treatment option. It’s an over-the-counter cream that can shorten an outbreak by anywhere from a few hours to a day. The cream must be applied several times per day.
Cold sores can also be treated with oral antiviral medications, such as acyclovir (Zovirax), valacyclovir (Valtrex), and famciclovir (Famvir). These drugs are available by prescription only. Your doctor may instruct you to take antiviral medications regularly if you’re experiencing complications with cold sores or if your outbreaks are frequent.
Symptoms may be eased by applying ice or washcloths soaked in cold water over the sores. Alternative treatments for cold sores include using lip balm containing lemon extract. Taking lysine supplements on a regular basis is associated with less frequent outbreaks for some people.
Aloe vera, the cooling gel found inside the leaves of the aloe plant, may bring cold sore relief. Apply aloe vera gel or aloe vera lip balm to a cold sore three times a day.
A petroleum jelly such as Vaseline won’t necessarily heal a cold sore, but it may ease discomfort. The jelly helps prevent cracking. It also serves as a protective barrier against outside irritants.
Witch hazel is a natural astringent that may help dry out and heal cold sores. Even so, the verdict is still out on whether cold sores heal faster if they’re kept moist or dry.
Always apply home remedies, creams, gels, or ointments to cold sores using a clean cotton swab or cotton ball.
Canker sores vs. cold sores
Canker sores and cold sores both cause pain and discomfort, but that’s where their similarities end. Canker sores are ulcers that occur on the inside of the mouth, tongue, throat, and cheeks. They are usually flat lesions. They are not contagious and are not caused by the herpes simplex virus.
Cold sores are usually found on the lips and outside the mouth. They are highly contagious. Cold sores are raised and have a “bubbly” appearance.
To prevent spreading cold sores to other people, you should wash your hands often and avoid skin contact with others. Make sure you don’t share items that touch your mouth, such as lip balm and food utensils, with other people during an outbreak.
You can help prevent the reactivation of the cold sore virus by learning your triggers and taking steps to prevent them. Some prevention tips include:
- If you get cold sores when you’re in the sun, apply a zinc oxide lip balm before soaking up some rays.
- If a cold sore pops up each time you’re stressed, practice stress management techniques such as meditation and journaling.
- Avoid kissing anyone who has a cold sore, and do not perform oral sex on anyone who has active genital herpes.