Cold Sores 101: What They Are, How They Develop & Treatment

Kristin Hall, FNP
Medically reviewed by Kristin Hall, FNP Written by Our Editorial Team Last updated 9/03/2020

Embarrassed by a cold sore? You’re definitely not alone. Cold sores are an extremely common annoyance that affect millions of Americans every year. 

Also known as fever blisters, cold sores typically develop on and around the lips and mouth as small, fluid-filled blisters. Over several days or weeks, they can break open and develop into a crust before healing. 

Cold sores are caused by the HSV-1 variation of the herpes virus, which affects around 67% of people worldwide under the age of 50, according to World Health Organization data.

In short, cold sores are annoying, potentially embarrassing and extremely common. Thankfully, they’re also extremely treatable. 

Below, we’ve covered everything you need to know about cold sores, from what they are to how they develop and spread. We’ve also listed and compared the most effective treatments for cold sores, ranging from science-backed antiviral medications to over-the-counter products.

What Are Cold Sores?

Cold sores are small, red blisters that can develop near the lips and mouth. The most common location for cold sores is the lips. However, it’s also possible for cold sores to pop up elsewhere on the face, as well as on the fingers (known specifically as herpetic whitlow) and nose.

In some cases, cold sores can also develop on the gums, the roof of the mouth and even inside the nostrils. 

Cold sores are also referred to as fever blisters, or as herpes labialis. They often develop in groups of two or more sores. Cold sores contain infectious fluid that can leak out onto the skin if the blisters break open, after which they typically develop into a crust and gradually heal.

What Causes Cold Sores?

Cold sores are caused by the HSV-1 variation of the herpes virus. Unlike HSV-2, which usually affects the genitals, HSV-1 primarily causes the development of cold sores (herpes lesions) on and around the lips and mouth. 

HSV-1 is extremely prevalent. More than two thirds of all people worldwide under the age of 50 have the virus, making it one of the world’s most common viral infections. 

Although cold sores are caused by the HSV-1 virus, not everyone with HSV-1 will develop cold sores. In fact, most infections of HSV-1 are asymptomatic, meaning the people infected by the virus won’t ever experience any symptoms

However, even if you’re asymptomatic, it’s still possible to transmit the HSV-1 virus to others if you’re infected.

How Cold Sores Develop

Cold sores go through several distinct stages as they develop. The process usually starts with a tingling or burning sensation around the mouth before developing into one or several small, red, fluid-filled blisters:

  • The first stage of a cold sore is considered the latent stage. During this stage, you won’t experience an outbreak or exhibit any symptoms of one, but you may still shed HSV-1 or HSV-2.

  • During the second stage, known as the prodromal stage, you may feel a slight tingling or burning sensation around your lips or on your face. This sensation won’t be explained by anything, such as a pimple or skin injury.

  • The third stage of a herpes outbreak is considered the inflammation stage. If you haven’t taken proper precautions to treat the outbreak in the prodromal stage, this is when sores will start developing. You’ll start feeling discomfort and swelling in the affected area, and it typically lasts for about a day.

  • The fourth stage is considered the pre-sore stage. At this point, a blister or blisters have developed on or around your mouth and nose, and things like eating, drinking or even speaking can be irritating and uncomfortable.

  • During the fifth stage, your cold sore or sores have have opened into an exposed sore, and will remain open for a couple days. Cold sores are highly infectious at this point, so be especially cautious not to risk spreading the fluid from the stores, or make skin-to-skin contact with anyone. No kissing!

  • By the time you reach the sixth stage of a cold sore outbreak, your open sores have crusted over and have begun the healing process. It usually takes two to three days for the crust to completely scab over.

  • The seventh stage of a cold sore is characterized by scabbing. At this point, a fresh scab has covered the sore, and the affected skin underneath is healing. This process can last several days, and it’s important to remember that the lesion is still infectious at this time.

  • Finally, the eighth stage of a cold sore occurs once the scab has fallen off. The affected area may still appear red for a couple more days while it continues to heal.

Altogether, this process can take several days to even weeks to heal. It’s common and quite normal for more than one cold sore to develop, break open and heal at the same time. 

Most of the time, people with symptomatic HSV-1 experience about one outbreak of cold sores per year. However, if you have a weakened immune system, or if you’re exposed to sunlight or another environmental factor that can trigger cold sores, you might get outbreaks more often. 

It’s also possible for factors like medication use, stress, certain illnesses and skin diseases such as eczema to contribute to cold sore outbreaks. 

How Cold Sores Spread

Cold sores are caused by the HSV-1 variant of the herpes virus, meaning that any activity that can spread HSV-1 can also potentially pass cold sores on to other people.

HSV-1 spreads through contact with the fluid that’s secreted from cold sores. For example, if a person with cold sores caused by HSV-1 kisses another person, their  saliva can pass the virus on relatively easily.

It’s also possible to pass HSV-1 by sharing utensils, toothbrushes and other objects that come into contact with an infected person’s saliva. This is known as indirect contact, and it’s one of the non-sexual ways for the herpes virus to spread.

Finally, as most people already know, it’s possible to transmit the herpes virus through sexual contact. The HSV-1 variant of the virus typically spreads through oral sex, while it’s possible for the HSV-2 variant to spread through oral, vaginal or anal sex.

Although transmission of the virus is most common during an outbreak, it’s possible to spread HSV-1 even if the infected person is asymptomatic. We’ve covered this, and other ways for the herpes virus to spread, in our guide to how herpes is transmitted between people

How to Treat Cold Sores

Cold sores usually heal on their own, meaning there’s no need to treat them if you’re comfortable waiting for them to disappear, and if you have generally good health with no major or chronic health conditions.

Since cold sores look unsightly and can be uncomfortable, wanting to speed up the body’s natural healing process is reasonable — and common. 

Unfortunately, there’s no cure for cold sores. If you have the HSV-1 virus and you get cold sore outbreaks, nothing can stop them from happening. However, by treating them early, it’s possible to speed up the healing process and get rid of cold sores faster than the usual two weeks.

Antiviral Medications

The most effective treatment for cold sores is the use of antiviral medication. These drugs work by preventing the herpes virus from replicating efficiently within the body, making it easier for the body’s immune system to target and control the virus.

One of the most effective antiviral medications used to treat cold sores is valacyclovir, the active ingredient in Valtrex®.

Valacyclovir is used to treat both HSV-1 and HSV-2. A 2003 study found that when people with cold sores use valacyclovir early in the cold sore’s development cycle, the sore heals faster and is less likely to cause lasting discomfort. 

In some cases, valacyclovir can also block the development of a cold sore, meaning you might not develop a physical blister even with early symptoms.

Valacyclovir is a prescription medication. You’ll need to talk to a healthcare professional before you can purchase it. We offer valacyclovir online with discreet delivery to your home, following an online medical assessment..

Other antiviral medications used to treat the herpes virus include acyclovir and famciclovir, both of which work similarly to valacyclovir. 

Over-The-Counter Cold Sore Treatments

Cold sores can also be treated using over-the-counter medications. Most over-the-counter cold sore treatments are topical medications that need to be applied directly to the area of skin that’s affected by a cold sore. 

One common over-the-counter cold sore treatment is docosanol — a topical ointment that works by preventing the herpes virus from spreading into the skin cells. In the United States, docosanol is typically sold in a 10 percent concentration under the brand name Abreva®

In a 2001 study published in the Journal of the American Academy of Dermatology, researchers found that use of topical docosanol five times per day sped up the healing process for cold sores in people with HSV-1, all with only mild adverse effects. 

In short, docosanol works, although it might not be as effective at speeding up cold sore healing as oral antiviral medications like valacyclovir. 

As for non-pharmaceutical treatments like facial moisturizers, lip balms and other products that are marketed as being perfect for cold sores, these are likely best avoided. Most use ingredients that aren’t backed up by scientific data, and none are effective as proven FDA-approved treatments.

Other Ways to Speed Up Cold Sore Healing

Finally, you might be able to speed up cold sore healing via a healthy lifestyle. As we’ve covered in more detail in our guide to stopping a cold sore in its early stages, sleeping well, avoiding stressers and limiting your time in sunlight can all help to manage cold sore outbreaks. 

If your cold sores sting or just feel uncomfortable, applying a cold compress to the area around your lips can often help. Although it’s uncommon for a cold sore to cause serious pain, it’s okay to take pain relievers like acetaminophen (Tylenol®) or ibuprofen (Advil®) if your cold sores start to hurt. 

Additionally, simple measures  like not touching the cold sore may help to speed up the healing process, all while reducing your risk of transmitting the virus to others. 

In Conclusion

Cold sores and the HSV-1 virus that cause them are both exceptionally common. Although they can feel uncomfortable and look unpleasant, cold sores generally aren’t bad for you and tend to heal on their own over the course of about two weeks. 

To speed up the healing process or reduce the severity of a cold sore outbreak, you can use a proven, science-backed medication like valacyclovir. While this won’t get rid of cold sores right away, it can weaken the virus and help your immune system get rid of cold sores faster. 

Learn More About HSV-1 and HSV-2

Almost all cases of cold sores are caused by infection with the HSV-1 variation of the herpes simplex virus. Our guide to HSV-1 and HSV-2 lists and explains the main differences between these two variations of this common viral infection, as well as the most effective treatments. 

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.