Cold sores are painful blisters that typically form around your lips. A sore could also form inside your mouth, commonly around your gums or the roof of your mouth. They are caused by the herpes simplex virus, which is highly contagious.
It's not unusual for you to keep getting cold sores after you've developed it once. However, they'll be less severe when they recur.
Cold sores are also known as oral herpes or herpes labialis. They will typically appear around your lips, but they could also appear on other areas of your face, like close to your nose. A day or two before your cold sore blisters, you might feel an itch or a tingling sensation around your lips.
A cold sore could sometimes be misdiagnosed as a canker sore. A canker sore is a small, round, painful sore that forms inside your mouth.
Unlike cold sores, canker sores are not caused by a viral infection but can be triggered by hormonal changes, allergies, stress, or insufficient nutrients in your diet. While cold sores are contagious and can be passed from person to person, a canker sore is not contagious. A canker sore will also not form on the outside of your mouth.
About 50%¹ of the U.S. population is reported to have been infected by the type 1 herpes simplex virus, which generally causes cold sores before they reach adulthood.
However, not everyone with this virus will develop cold sores. Some people might not have any virus symptoms and will not know that they have it. Around 20 to 40%² of people infected with the virus will develop cold sores.
The frequency of cold sores is highly individual in people who have the herpes virus. If you have it, you might develop cold sore several times in a year or just once or twice ever. According to the World Health Organization (WHO)³, around 67% of people below age 50 across the globe have the type 1 herpes simplex virus.
Prevalence of herpes simplex virus type 1 and type 2 in persons aged 14–49: United States, 2015–2016 | Centers for Disease Control and Prevention
Cold sores: Overview (2006)
Herpes simplex virus | World Health Organization
The most prominent cold sore symptom is the painful cluster of blisters that forms on one side of your lips and the surrounding skin in that area. The blisters can make it painful to talk or chew.
Certain foods such as citrus fruits and spicy foods can further irritate the already painful sore. Children with the virus might develop a fever once infected with the virus. If you get a cold sore for the first time, you might also experience some of the following symptoms¹:
Swollen lymph nodes
These symptoms are unlikely to recur with subsequent cold sores.
A cold sore could last a couple of days to a few weeks, though it typically lasts about eight days. It tends to occur in stages, and most (>85%) people can feel it when a cold sore is about to come on.
Cold sores typically happen in the following stages.
Prodrome stage—you'll feel a tingling or burning sensation or an itch around your mouth, which will typically happen a day or two before your cold sore forms
Blister stage—typically filled with fluid and painful, a blister will form at a corner of your lip or, in some cases, inside your mouth
Weeping stage—when your blister breaks, it's known as the weeping or ulcer stage, and it is at this time that your sore is at its most painful and contagious
Crusting stage—a scab will form over your store a few days after the weeping stage
Healing stage—the sore will scab over and fall off a couple of times before completely healing
When your cold sore is completely healed, there should be no scabbing or scarring left and definitely no pain or other sensation.
The herpes simplex virus causes cold sores. There are two types of herpes simplex viruses—type 1 herpes simplex virus and type 2 herpes simplex virus. The type 1 herpes virus most commonly causes cold sores.
The type 2 herpes virus is more commonly responsible for genital herpes. However, it could also cause cold sores. Not everyone infected with the type 1 herpes virus will get a cold sore. While there's no cure for the virus once you contract it, it can stay dormant with the proper management.
Once you've been infected with the virus, it never goes away. However, it stays inactive until it's triggered.
What triggers a cold sore in you might not trigger a cold sore in the next person with the virus. Triggers such as a fever or stress could reactivate the virus and cause a cold sore. Other triggers include:
Getting the flu
Immune system deficiencies
A physical injury such as a cut around your lips
The type 1 herpes virus is highly contagious. You can contact it from a close friend or family who has already been infected. The herpes virus can be spread through saliva or by coming into close contact with a person who has the virus.
Certain classes of people are at a higher risk of contracting the herpes virus: neonates, healthcare workers, sexually active adolescents, and athletes.
A cold sore can affect people of any age. However, newborns and children are more at risk of contracting the virus. Newborns could get the virus from mothers who have the herpes virus but showed no symptoms during delivery.
People over 35 are less likely to develop cold sores¹ than younger people.
Healthcare workers are at significant occupational risk of getting the herpes virus and developing cold sores. They come in close contact with people who could have the virus daily. It's vital for people who work in the healthcare industry to wash and disinfect their hands before and after contact with any patients.
Sexual activity is a common way for people to contract the herpes virus. Anyone sexually active is at risk. However, sexually active adolescents are even more prone to getting the virus and developing cold sores.
Research² shows this is because adolescents are more likely to engage in sexually risky behaviors, such as neglecting to use condoms.
Athletes who play sports that involve extensive skin-to-skin contacts, such as wrestling or rugby, are more prone to developing the herpes virus.
Cold stores are highly contagious from the prodrome to the crusting stage. During these stages, you must think about preventing the spread of the virus to people who are close to you, especially those who are most at risk.
Once your cold sore has healed, it typically stops being contagious; however, HSV-1 can also be shed asymptomatically. To protect people around you from contracting the virus, you should take the following precautions:
When the fluid from your sore gets on your hands, it's easy to transmit. If you touch your cold sore, you should wash your hands immediately after.
To avoid spreading cold sores, don't share personal items with other people, like razors, toothbrushes, cutlery, or makeup. This applies even after it has healed.
While your cold sore is healing, you should avoid intimate contact with others to prevent the virus from spreading. You should be especially cautious around children, as their immune systems are still developing, and contracting the herpes virus can be more severe for them.
If you have a cold sore, wash your hands several times during the day, even when you've not touched your sore.
Cold sores are often confused with canker sores and other oral sores. What distinguishes a cold sore from other mouth sores is its cause, which is the herpes simplex virus.
To properly diagnose your cold sore, your doctor will physically examine it. Cold sores typically form in small clusters of fluid-filled blisters. If your sore is at the blister or weeping stage, your doctor could test if the fluid is positive for the herpes virus.
Cold sores are usually nothing to worry about. They'll go away in a week or two. Complications are very rare. When they do occur, they could affect your eyes, genitals, or other body parts.
Although the type 2 herpes virus is typically responsible for genital sores, the type 1 herpes virus could also cause genital sores in some cases. A person with type 1 herpes virus might infect another person through oral sex.
You can get an eye infection by touching a cold sore and touching your eye with a contaminated hand. If the type 1 herpes virus infects your eye, it could cause an infection known as herpes simplex keratitis³, which affects the cornea. A severe infection could even result in blindness.
In people who have eczema, the herpes virus can cause a deadly infection known as eczema herpeticum⁴. Symptoms include fever, swollen lymph nodes, and fatigue.
The infection could be life-threatening in children and immunocompromised people.
If you have a weakened immune system either due to medication such as chemotherapy or conditions like HIV, getting the herpes virus could cause brain swelling⁵. Your cold sores are also likely to be more severe and take a longer time to heal.
People who have just been infected with the herpes virus might also develop an infection of the mouth and gums known as herpetic gingivostomatitis⁶. Its symptoms include fever and painful lesions on your gums.
Some people with the herpes virus might also develop herpetic whitlow⁷. It's a painful infection that causes small painful blisters to form on your fingers.
While this condition can affect people of any age, it's most common in children who suck on their thumbs and healthcare workers who have been exposed to the virus without wearing gloves.
Herpes simplex keratitis (2022)
Eczema herpeticum (2022)
Encephalitis, herpes simplex | National Organization for Rare Disorders (NORD)
Herpetic gingivostomatitis (2022)
Herpetic whitlow (2022)
A cold sore will usually go away on its own in a few weeks. They are mild and don't require you to treat them in most cases.
However, some treatments can help speed up your healing process and prevent cold sores from recurring in the future. Treating your cold sore effectively also reduces the risk of you spreading the herpes virus to other people.
The following treatment options are available for treating cold sores, depending on what stage your cold sore is in.
Antiviral medications such as acyclovir and famciclovir are great in helping to prevent cold sores from happening. They also help reduce the frequency of cold sore outbreaks and the severity in cases where they occur.
In 2021, a study was done into the effectiveness of using acyclovir as a patch for treating cold sores. Researchers found that the patches effectively relieved symptoms during the blister and weeping stage. However, they don't help much during the crusting and healing stages.
Medications with numbing agents can help reduce the itching and pain you feel during a cold sore's blister and weeping stage.
Cracking is likely to happen during the blister and healing stages of a cold sore. Emollients can help with this. They can also soften the scabbing over your cold sore.
You can take over-the-counter painkillers if your cold sore is causing a lot of pain. Your doctor might also prescribe lidocaine, a type of painkiller you can apply directly to your cold sore.
It's essential to begin treatment at the first signs of a cold sore. While these treatments can help alleviate cold sore symptoms, they don't cure the herpes virus.
Cold sores can be painful and cause significant discomfort. Even with treatment, they will take at least a couple of days to heal. These home remedies can help quicken the healing process and ease your discomfort.
Use a cold compress—to ease the swelling and discomfort you feel from a cold sore
Watch your diet—avoid any foods that will aggravate your cold sore, including those with high acidic content
Wear sunscreen—this helps during the crusting and healing stages of your sore to protect your skin while it's healing
The key to preventing cold sores is preventing the spread of the herpes virus. To protect yourself from contracting it, you should take the following precautions:
Avoid intimate contact with people who have the virus
Avoid sharing personal belongings such as toothbrushes or cutlery
Wash your hands frequently and properly
Avoid touching a cold sore to prevent the virus from infecting other parts of your body
If you already have the herpes virus, no worries. You can still prevent cold sores from occurring or reoccurring. Always remember to apply sunscreen whenever you are outdoors, especially to your lips.
Keep your stress in check. Engaging in stress management techniques such as meditation, deep breathing, eating well, and getting enough sleep are great ways to help you manage stress.
You must also replace your toothbrush regularly. According to the Centers for Disease Control and Prevention (CDC)¹, a good rule of thumb is to replace your toothbrush every three to four months.
Finally, eat a balanced diet. Nutritional deficiencies can trigger a cold sore to form.
If sores begin to pop up in other parts of your body, such as around your eyes and genitals, you should contact your doctor as soon as you can. It's crucial to treat cold sores immediately in these cases. If left untreated, they could lead to more complications.
A dermatologist is a specialist who treats skin conditions. When you have a cold sore that is severely uncomfortable or doesn't appear to be healing, you'll most likely be referred to a dermatologist for treatment.