How to know if it’s a cold sore or something else

There may be no question in your mind when you notice a hard, red cluster of bumps on or near your lip in the mirror: It’s a cold sore. But perhaps you’ve never had a cold sore before, or something about this one feels different from others you’ve had previously. How can you be sure that it is, in fact, a cold sore?

If this is your first time getting a cold sore, it can be frustrating to not know for sure what’s happening in your body. But you’re not alone. According to the World Health Organization, more than half the global population – about 3.7 billion people – have the virus that causes cold sores.

It’s normal to have some doubt when other conditions look or feel like cold sores. Below, we’ll go over the main characteristics of cold sores and try to separate them from other, similar conditions.

How cold sores look, feel and act

Cold sores are caused by a type of virus called the herpes simplex virus (HSV). Once you contract this virus, it stays in your body for life. The herpes simplex virus will be dormant much of the time, but it can resurface occasionally, resulting in a cold sore. When and how often you get cold sores, if you get them at all, depends on your unique immune system. Some people with HSV never get a cold sore, some only get one a year, and some get them a few times a year.

Here’s what you need to know about cold sores.

You can feel a cold sore coming

Cold sores are often preceded by a tingling, itching or burning sensation on the area of your lip where they will appear. This is called the prodromal stage, and it can last anywhere from several hours to two days before one or more cold sore blisters develop.

A cold sore reappears in the same spot every time

You’ll find that your cold sores pop up in one particular spot on or near your lip each time you get one. This is because the herpes simplex virus resides in and travels along just one area of the lips’ nerve cells. It wants to stay in the same spot, so when you have an HSV resurgence, the resulting cold sore will be concentrated near those same nerve cells.

A cold sore follows the same stages

Each time you get a cold sore, it will follow a similar progression:

• A tingling, itching or burning sensation starts several hours or days before an outbreak at the site where the cold sore will occur (prodromal stage).
• After 1-2 days, one or more small, fluid-filled blisters develop on or around the lips.
• After 3-4 days, the blisters burst and their fluid drains. This is known as the ulcer stage or weeping stage. Cold sores are extremely contagious, and they’re most contagious during this time.
• The blisters form scabs and begin to heal.
• The scabs become smaller and smaller, and eventually disappear, typically leaving no scar behind.

A cold sore lasts about 10 days, but the first one can linger longer

The cold sore progression, from their first appearance to once they’re fully healed, takes an average of 7-10 days. The first cold sore you ever get is often more intense and can take closer to three weeks to heal. It’s often accompanied by flu-like symptoms.

A cold sore causes one or more blisters, surrounded by inflamed skin

The appearance of a cold sore can vary: You may have one large blister or a cluster of several small ones. These blisters will form on the skin of your upper or lower lip, but can spread beyond your lip’s border and onto the skin of your face. In rare instances, you can get a blister near your nose or on your chin. The blisters are ringed with red, inflamed skin, and the fluid inside them will be clear or tinted yellow.

A cold sore shows up after exposure to a trigger

You may have already figured out what causes you to get cold sores – this is your cold sore “trigger.” You can have more than one, and it could be something like cold weather, an illness, changes in your diet or stress. If you find that spending time outside on a chilly, windy winter day or recovering from a nasty cold always seems to give you a tingling, painful spot on your lip, those could be your triggers.

Other types of mouth sores that a cold sore can be mistaken for

The above features sound pretty distinct to cold sores, but it turns out other common conditions – including pimples, ingrown hairs, canker sores, angular cheilitis, mucoceles and other lip blisters – can share some of the same characteristics. But here’s how they differ from cold sores:

It’s rare to get a pimple or ingrown hair directly on the skin of your lip

Cold sores and pimples can both be tender to the touch and full of fluid. But unlike a pimple, a cold sore typically has a larger area of red, inflamed skin around it and no discernable whitehead. You can see the fluid inside a cold sore, and it should be clear or straw-colored, not white like pus.

Your lips have no oil glands or hair follicles, so it’s rare that a pimple would form directly on the skin there. No matter if it’s a pimple or a cold sore, attempting to pop it will make it significantly worse. It’s best to leave it alone.

The same goes for an ingrown hair. When a hair that has been shaved, plucked or waxed regrows incorrectly and either curls under the skin or curves back into the skin, it becomes an ingrown hair. It can cause itchy irritation, a red bump and a pimple. An ingrown hair mistaken for a cold sore, or vice versa, applies mostly to people who shave the area around their mouth. This is where ingrown hairs will occur, not on the skin of your lips.

A canker sore or mucocele will be inside your mouth, not outside of it

Canker sores are small, round wounds that form on the tissue lining the inside of the mouth. They can be caused by:

• Food and drink allergies
• Mouth injuries, like accidentally biting the inside of your cheek or getting hit in the mouth playing sports
• Sensitivity to certain ingredients in toothpaste and mouthwash, such as sodium lauryl sulfate

Unlike cold sores, canker sores are not contagious. They tend to heal on their own in about two weeks, but there are ointments and mouth rinses available to speed up the healing process.

A mucocele, or an oral mucous cyst, is a harmless, fluid-filled bump that will also appear on the inside of the mouth, typically the lower lip, when one of the salivary gland openings becomes clogged.

Mucoceles are seen most often in children but can happen to anyone younger than 30. They’re caused by chronic lip biting or a mouth injury. Don’t try to pop the mucus cyst yourself. It should go away on its own in 3-6 weeks, but if it persists, visit a primary care provider or dentist for treatment.

Angular cheilitis forms dry cracks in the corners of your mouth

When saliva consistently builds up in the corners of your mouth, it irritates the tender skin there as it dries. This dryness and irritation can lead to small, painful cracks and even a bacterial, fungal or yeast infection. This is a condition known as angular cheilitis.

Angular cheilitis affects people of any age and has many underlying causes, including:

• A misaligned bite
• Ill-fitting dentures
• Repetitive lip-smacking and thumb-sucking behaviors
• Thrush
• Diabetes
• Certain antibiotics and isotretinoin
• Deficiencies in iron or vitamin B

Angular cheilitis is not contagious and won’t spread beyond the corners of the lips in most cases. It causes skin to appear dry, red, flakey and cracked, but doesn’t cause blistering.

Angular cheilitis tends to go away on its own, but keep the area clean and moisturized with ointments, like petroleum jelly, to protect it.

Some lip and mouth blisters are the result of burns or allergic reactions

Blisters on the lip can have other causes that are unrelated to the herpes simplex virus. If you burned your lips recently, whether by consuming something that was way too hot or being out in the sun for too long with no sunscreen, you can get a blister accompanied by redness, pain and swelling.

An allergic reaction will typically cause your lips to swell all over, rather than just in one spot. Same with a traumatic injury, like being hit in the mouth.

A bad burn, injury or allergic reaction can trigger a cold sore, but more often the resulting blister or swelling will be a direct result of the injury or exposure to the allergen.

Getting treatment for cold sores and more

If you’re not sure whether the painful spot on your lip is a cold sore or something else, make a primary care appointment. Your doctor or clinician can examine your lip and perform any necessary tests to tell you exactly what’s going on.

Most cold sores heal on their own in 7-10 days. But with over-the-counter or prescription antiviral treatment, you can heal cold sores more quickly. Your doctor can prescribe antiviral medications to help lessen the severity and duration of cold sores. These medications are most effective when they’re started within 72 hours of when symptoms first begin.

If you feel like you need care as fast as possible, you can also get a cold sore diagnosis or an antiviral prescription online with Virtuwell.

If your cold sore is lasting longer or feeling more painful than usual, or you’re getting more than 6-8 cold sores each year, make a primary care appointment. In some cases, your doctor may recommend a daily antiviral medication to help prevent cold sores.