Have you ever noticed a small, painful, fluid-filled blister on your face or mouth?
If not, consider yourself lucky—nearly 90% of the global population suffers from cold sores.
Cold sores, also known as fever blisters, are caused by the two types of herpes simplex virus—HSV-1 and HSV-2.
Although that may sound scary (as herpes is generally associated with sexual contact), cold sores are actually just as treatable as they are common.
This article walks you through everything you need to know about cold sores. That way, you can take preventive action in the future and understand what they mean if/when they pop up.
Overview: What Is A Cold Sore?
Cold sores—sometimes called fever blisters—are small, painful blisters that form on or around the lips. They are a specific type of mouth sore caused by a contagious virus that can be transferred through contact with saliva or skin-to-skin contact.
Usually, skin-to-skin or salivary contact is through common behaviors like kissing, sharing drinks, or sharing utensils. That's part of what makes this disease so contagious—most people don't know they have it or worry about spreading it through seemingly normal activities.
The scientific term for cold sores is herpes labialis. It’s caused by the herpes simplex virus (HSV). HSV-1 usually causes oral infections, while HSV-2 is more common with genital herpes.
Certain triggers like stress, dehydration, sun damage, and certain foods can provoke an outbreak, but the root cause of cold sores remains the same.
If a patient does not have either variant of the herpes simplex virus, they will not have cold sores. If they do, these triggers can cause an outbreak.
Cold sores usually last up to two weeks and can be quite painful, but they usually go away on their own.
Signs & Symptoms Of Cold Sores
The symptoms of cold sores vary from person to person. And many people with the infection never experience any physical symptoms.
For the millions who do, the signs are:
Tingling And Itching
Tingling and itching are usually the first signs of a cold sore—when an outbreak is imminent, you might feel a tingly, burning sensation around your lips.
This generally occurs before the sore actually forms. Up to 48 hours before the blister erupts, you might feel an intense itching sensation.
In some cases, cold sores can cause numb mouth and lips. This is because the virus has been attacking and damaging your nerves, which can lead to numbness in the affected area.
This numbness is temporary and usually only lasts for the duration of your cold sore flare-up.
The next sign of a cold sore is the development of fluid-filled blisters. These are red, often painful bumps around your mouth or on your lips that can break and form an open sore.
The amount of pain users feel will vary based on how large the blisters are, their location on the mouth, and the person's individual pain tolerance.
Oozing And Crusting
Once the blisters have opened, they may form a thick yellow-colored crust before they eventually heal.
As the cold sore heals, it will continuously ooze this thick yellow gunk. This typically lasts anywhere from a few days to a week.
It's important to note that cold sores are contagious at all stages of the outbreak—this includes while the blister is forming and when it has already ruptured.
Medical Causes Of Cold Sores
There are two main medical causes of cold sores: Herpes simplex virus 1 (HSV-1) and Herpes simplex virus 2 (HSV-2).
Herpes Simplex Virus (HSV 1)
HSV-1 is the more common cause of cold sores, as it's usually what causes oral herpes. It’s spread through saliva or skin-to-skin contact—for example, when someone with a cold sore kisses you, shares a drink, or uses the same utensils as you.
Although HSV-1 can cause genital herpes, it’s much less common than HSV-2 which is usually responsible for that manifestation of the virus.
Herpes Simplex Virus (HSV 2)
HSV-2 is the second major cause of cold sores. It’s the form of the HSV virus that is typically responsible for genital herpes.
HSV-2 is also spread through saliva or skin-to-skin contact. It's commonly spread through sexual contact with an infected person, and it can be passed from mother to baby during childbirth.
What Triggers A Cold Sore Outbreak?
Several different factors can trigger a cold sore outbreak. Although many of them are seemingly random, there are usually underlying causes that users need to be aware of in order to take preventative measures in the future.
Common triggers for cold sores include:
Certain foods, such as chocolate and peanuts, have been known to trigger an outbreak in some people.
Below is a list of foods that can provoke a cold sore outbreak:
- Foods that contain L-arginine: L-arginine is a common amino acid that is found in many foods, including chocolate, peanuts, tree nuts, seeds, and oats. It can also be found in dairy products and certain grains.
- Foods that contain acidic ingredients: Acidic ingredients like vinegar, citrus fruits, and tomatoes can cause inflammation in the lips and trigger a cold sore. They can also make existing sores more painful, as the acid can get underneath the cold sore's surface.
- Processed foods: During a cold sore outbreak, some foods can weaken your immune system and make it more likely for the virus to return. To avoid this, steer clear of processed snacks like sugary breakfast cereals, packaged snacks, frozen meals, or canned goods that are high in calories. Instead, opt for fresh produce and whole grains—these are better options as they will help keep you healthy during an episode of cold sores.
Stress and oral health have a significant relationship. It can weaken the immune system, leaving it unable to fight off the virus responsible for cold sores.
Stress also causes your body to produce hormones that can make your skin more sensitive and prone to infection.
Stress-induced cold sores are triggered by a combination of factors including stress, physical exhaustion, hormonal changes, diet, and environment.
Fever can be a sign of a weakened immune system, and with a weakened immune system comes an increased risk of cold sores.
People who have a high fever or are dealing with long-term illnesses such as HIV/AIDS may be at even higher risk of developing cold sores due to their inability to fight off the virus that causes them.
Cold and flu season can be a challenging time, particularly if you’re prone to cold sores. As both colds and the flu weaken your immune system, they can trigger an outbreak of cold sores, so it's important to take precautions during this time.
The same reason some call it a "fever blister," many call this type of sore a "cold sore" because it comes out when you have a cold.
Like many other cold sore causes, allergies cause the immune system to weaken. This makes it easier for HSV to become active in your body and display the symptoms of cold sores.
Additionally, certain allergens such as pollen or dust mites can trigger inflammation in the body that can also lead to a cold sore outbreak.
Cold sores are a common symptom of fatigue. Similar to how stress can weaken your immune system, so too can not getting enough sleep.
Not getting the recommended seven to eight hours of sleep each night will make it difficult for your body to fight against the virus that causes cold sores.
To prevent a cold sore outbreak, it's important to get plenty of rest and relaxation.
Dental Work Or Cosmetic Surgery
There are a few ways that you can contract cold sores from dental work or cosmetic surgery.
- A dentist or surgeon may unknowingly spread the virus from one patient to another if they do not use proper sterilization techniques.
- Some dental treatments or procedures may irritate your gums and lips, causing them to become vulnerable to infection.
- Dry mouth from certain medications or anesthesia can increase your risk of developing cold sores.
- Preexisting oral health problems can make you more susceptible to cold sores after treatment.
For this reason, it's important to let your dentist or doctor know if you have a history of cold sores before undergoing any treatments.
During menstruation, the body experiences a number of hormonal changes, which can lead to an increase in stress and fatigue. This weakened immune system may allow the herpes simplex virus (HSV), the virus responsible for cold sores, to become more active.
Additionally, during menstruation there is an increase in blood flow to the lips and face, allowing HSV to transfer between cells more easily.
Studies also show that hormonal contraception (i.e., birth control pills), pregnancy, and menopause can cause a cold sore outbreak. These are called “hormonal cold sores,” and they occur when the body's hormones fluctuate due to changes in the reproductive system.
Injury To The Skin
Injury to the skin around your lips or mouth can open the skin up to a cold sore infection. Sunburns, scrapes, and other types of injuries may increase your risk for a cold sore outbreak.
In addition, trauma or stress in the area can also trigger an outbreak. For example, biting your lip or picking at a scab can cause a cold sore.
Certain skin conditions, such as eczema and psoriasis, may increase the risk of developing cold sores as well as cause them to develop in larger parts of your body.
Cold Sore Stages (With Images)
There are five stages of cold sores: Tingling, blistering, weeping, crusting, and healing.
Stage 1: Tingling
In the first stage, you may feel a tingling or itching sensation around your mouth. This is one of the most common symptoms of cold sores and can last up to two days before blisters form.
Some people don't notice any symptoms during this stage, but for others, the area may be painful and sensitive to the touch.
Stage 2: Blistering
After tingling for a day or two, the area around your mouth will begin to form blisters. These can range from small to large and may be accompanied by pain, redness, and swelling.
It's common for these blisters to form in the corner of your mouth and spread outward, but they may also appear as spots on your mouth.
Stage 3: Weeping
In the "weeping" phase, the blisters will begin to break open and leak a yellowish fluid. This is a sign that the virus is most active and contagious, so avoiding contact with other people (e.g., sharing drinks, lip balm, or lipstick) is essential.
During this phase, your condition will also be at its most painful and uncomfortable. Avoiding touching your cold sores is important to help prevent the spread of infection, as is avoiding acidic or spicy foods that may irritate the area.
Stage 4: Crusting
Although you may still feel some pain or discomfort in this stage, the blisters will start to dry and form a yellow-brown crust.
This is a sign that your body is starting to heal, but it's important to continue avoiding contact with other people or objects until the crust has fully formed.
Stage 5: Healing
In the healing stage, your cold sores will begin to heal and the scabbing will start to flake off. This is when you can finally resume contact with other people without worrying about spreading the virus.
Although this is usually a sign of successful healing, it's important to keep the area clean and moisturized to help prevent further infection.
If you experience any pain, redness, swelling, or blistering that doesn't go away after two weeks, contact your doctor or dentist for further advice.
What Are The Complications Associated With Cold Sores?
Most of the time, cold sores are quite easy to deal with—you just wait until they go away. In some cases, oral or topical creams may be prescribed to help reduce the symptoms.
However, cold sores can also lead to more serious complications if not treated properly.
If a cold sore comes into contact with your eye, it can cause an infection called herpes keratitis.
You can infect your eye from a cold sore in a few different ways:
- Touching the cold sore and then your eye,
- Rubbing your eye after coming into contact with someone else's cold sore
- Sharing cosmetics with someone who has a cold sore
This condition is particularly dangerous and requires immediate medical attention.
Genital herpes is another complication that can arise from cold sores. Genital herpes is not usually caused by HSV-1, but it can be if someone with a cold sore performs oral sex on an uninfected person.
It's also possible to transfer the virus from one area of your body to another, such as your genitals. This is called autoinoculation and requires prompt medical treatment.
In most cases, HSV-2 is the type of herpes that causes genital sores.
Regardless, it's important to avoid intimate contact with someone who has a cold sore, as this increases the risk of transmission.
How To Relieve Symptoms Of Cold Sores
The good news about the symptoms we've discussed is that they can usually be managed quite easily.
Here are some of the best ways to manage your cold sore symptoms:
Use Over-The-Counter Creams.
Over-the-counter creams like docosanol and acyclovir can help to reduce the duration and painfulness of a cold sore.
These topical solutions usually cost between $15-$25 and can be applied directly to the sore.
You can usually find them in a section of your local pharmacy, and you don't need a prescription to buy them.
If you're looking for a heavy-duty, prescription-strength option, your doctor may prescribe an antiviral medication like topical penciclovir ointment.
Take Pain Relievers.
Non-steroidal anti-inflammatory medications (NSAIDs) like ibuprofen or aspirin can help to reduce the pain and discomfort of a cold sore.
These medications are easy to find at any drug or convenience store, and most people already have them in their homes.
Beyond pain management, they can also suppress a fever. If an illness is causing your cold sores to flare up, taking an NSAID can help reduce your fever and thereby reduce the severity of the outbreak.
Wear Sunscreen And SPF Lip Balm.
Since sun damage can lead to cold sores, it's important to take preventative measures. Wearing sunscreen and lip balm with SPF can help protect your skin from the sun's harmful rays.
You should also try to stay out of direct sunlight when you have a cold sore, as this will make the condition worse.
Avoid Acidic Foods.
Acidic foods like citrus fruits and tomatoes can irritate a cold sore and make it worse.
It's best to cut these foods out of your diet altogether if you have an active outbreak.
Also, try to avoid salty or spicy foods, as these may also aggravate the sore and delay the healing process.
Apply A Cool Compress.
A cool compress is a simple and effective way to reduce inflammation and discomfort caused by cold sores. It involves applying a cold, wet cloth or towel directly to the area affected by the sore.
The compress should remain in place for 10-15 minutes at a time, several times daily.
How Can You Prevent Cold Sores?
The best way to avoid cold sores is to take preventive measures to protect your oral health and overall well-being.
Here are some tips for preventing cold sores:
Stay Healthy And Practice Good Hygiene.
It's important to maintain a healthy lifestyle in order to keep your immune system strong and prevent illnesses that could trigger cold sores.
- Eating a healthy diet
- Exercising regularly
- Staying hydrated
- Avoiding stress
You should also practice good personal hygiene (e.g., regularly washing your hands and brushing your teeth twice per day), as this can help reduce the risk of spreading the virus.
Get Enough Rest.
Sleep is essential for keeping your immune system functioning well. Lack of sleep can weaken your body's natural defenses and increase your risk of developing a cold sore.
Make sure to get at least 7-8 hours of sleep each night in order to keep your immune system strong.
Wear Lip Balm With SPF.
Just like sunscreen protects your skin from the sun's harmful rays, lip balm with SPF can protect your lips from the sun.
This will help to prevent further damage (e.g., mouth rash) and reduce the risk of cold sores.
Avoid Direct Contact With Someone Who Has A Cold Sore.
Cold sores are highly contagious, so it is important to avoid direct contact with someone who has an active outbreak.
Sharing drinks, utensils, or cosmetics with someone who has a cold sore can increase your risk of becoming infected.
If you are around someone with an active outbreak, always use a tissue to cover your mouth when coughing or sneezing, and wash your hands afterward.
The Bottom Line
Like canker sores, cold sores are common, painful, and unpleasant. And even though there is no cure for the virus that causes them, there are treatments available to manage symptoms.
Taking precautions like wearing sunscreen, avoiding acidic foods, and practicing good hygiene can also help prevent cold sores from occurring in the first place.
With some basic lifestyle changes and a bit of knowledge about how to handle an outbreak, you can keep cold sores at bay.
Want to learn more? Here are a few questions our customers frequently ask us.
Can Cold Sores Spread?
Yes, cold sores can spread from person to person through direct contact. The virus that causes cold sores is very contagious, so avoiding skin-to-skin contact with someone who has an active outbreak is critical. Sores can also spread through indirect contact, such as sharing drinks, utensils, or cosmetics with someone who has a cold sore.
Can Cold Sores Spread To Other Parts Of Your Body?
Cold sores usually stay concentrated to the oral area, but it is possible for the virus to spread to other areas, such as your eyes or genitals. If you suffer from psoriasis, eczema, or other conditions that cause skin irritation, the virus can also spread to those areas as well.
How Can You Get A Cold Sore?
Most people get cold sores from direct contact (e.g., kissing, sex, or other bodily contact) with someone who has an active outbreak. People can also get cold sores through indirect contact (e.g., sharing drinks, food, or cosmetics) with someone who has a cold sore. This can happen whether someone with a variation of the HSV virus is in the middle of a flare-up or not.
Can You Get Cold Sores Inside Your Mouth?
Cold sores generally manifest themselves outside the mouth, but they may begin inside the mouth (e.g., on the gums or inside of the cheeks). It is possible to get cold sores inside your mouth, although it is uncommon, especially compared to getting them outside the mouth.
Can You Get Genital Herpes From A Cold Sore?
Yes, it is possible to get genital herpes from a cold sore. The virus that causes cold sores (HSV) can be spread through direct or indirect contact with someone who has an active outbreak. If you are engaging in oral sex with someone who has a cold sore, you are at risk of contracting genital herpes.
Can You Get A Cold Sore In Your Nose?
Yes, you can get a cold sore in your nose. This is usually caused by picking at or irritating the area around the nose, which can make the area around, inside, and beneath it vulnerable to an HSV infection.
What Is The Difference Between A Canker Sore And A Cold Sore?
Canker sores and cold sores are not the same thing. Canker sores are small, painful ulcers that form inside the mouth, while cold sores are caused by a virus (HSV) and usually appear outside the mouth. Furthermore, canker sores do not typically cause any other symptoms besides pain, but cold sores may also be accompanied by itching, burning, and tingling.
Can Babies Get Cold Sores?
Herpes simplex virus can be passed to an infant through a cold sore if the person who has one kisses them. The same applies for blisters on the breast, which may result in passing of herpes onto your little bundle of joy during breastfeeding or expressing milk from infected breasts.
Can Stress Cause Cold Sores?
Yes, stress can be a contributing factor to cold sores. Stress weakens the immune system and causes inflammation which can trigger outbreaks of herpes simplex virus (HSV). To prevent flare-ups, it's important to get adequate sleep and manage stress in healthy ways, such as exercising regularly and eating a balanced diet.
How Long Do Cold Sores Last?
Cold sores typically last anywhere from 7 to 14 days. The sore may start to heal after a few days but can continue to be contagious until it completely heals. Different stages of the infection (e.g., blistering, scabbing) may occur throughout the duration of the outbreak.
How Long Does It Take For A Cold Sore To Go Away?
Cold sores will usually go away within 7 to 14 days. However, the healing time can vary depending on the severity of the outbreak and any other underlying medical conditions that may be present. During this time, it is important to take measures to reduce discomfort and speed up recovery. This includes avoiding direct contact with the cold sore and keeping it clean and dry.
Should You Pop A Cold Sore?
No, you should not pop a cold sore. Popping a cold sore can worsen your condition and increase the risk of spreading the infection. Instead, you should apply a topical ointment or cream to the cold sore and take antiviral medication if advised by your doctor.