What Causes Cold Sores and Fever Blisters?

Cold sores and fever blisters have these names because people once believed they were the result of colds and fevers.  They are not caused by colds or fevers, but colds and fevers can put you at risk for them.

What is a Cold Sore/Fever Blister?

A cold sore and a fever blister are the same thing.  From here on, we will refer to them as cold sores, just for the sake of simplicity.  Cold sores consist of a small cluster of fluid-filled bumps, which burst to form tiny ulcers.  These ulcers then scab over while healing.  They can occur on the lips, which is most common, or on the inside of the mouth.  Inside the mouth, they typically appear on the roof of the mouth.

Most people who get cold sores frequently recognize the tingly feeling you get right before a cold sore appears.  This is called the prodromal phase.  If you catch it in this early stage, medications can shorten their lifespan and reduce their intensity.

What Causes Cold Sores?

The scientific name of cold sores is oral herpetic lesions because they are caused by the Herpes Simplex Virus-1.  This is not the same virus that causes genital herpes.  Oral herpes and genital herpes are caused by two different strains of the herpes simplex viruses.

In general, oral herpes lesions are HSV-1, and genital herpes lesions are HSV-2.  Over 3.7 billion people have HSV-1, and in most of those people, it does not cause any sores.  However, in other people, it causes painful and even embarrassing oral sores.

The billions of people who have the HSV-1 virus in their body usually have no symptoms at all.  Because the virus is inactive but present all the time, it is likely to become active when your immune system is down.

This is why things like colds and fevers can predispose you to cold sores.  When your body is trying to fight off something else, HSV-1 can creep up and cause active lesions.  Cold sores also commonly occur after sun exposure and dental visits.  Any minor damage to the lips (UV rays from sun exposure or minor stretching during a teeth cleaning) can be enough to spark a cold sore

How Do You Get HSV-1?

The virus that causes HSV-1 is so common that most people are exposed to it by the age of one year.  One person transmits the virus to another via oral-to-oral contact, like kissing or sharing drinks and eating utensils.  While it is possible to transmit the virus anytime, it is more likely to happen when you have an active sore.

How to Reduce Your Risk of Getting a Cold Sore?

There are a few steps you can take to make cold sores less likely.  These are not foolproof, but they may lower your risk.

  • Always wear chapstick with sunscreen protection of SPF 15 or greater.
  • Make sure your lips are well lubricated with Vaseline or chapstick before, throughout and after a dental procedure.
  • Take care of your immune system. Make healthy food and drink choices, and try to prevent any minor illnesses.
  • Avoid kissing or sharing drinks and eating utensils with anyone who has an active cold sore.
  • Reduce stress as much as possible, and get plenty of sleep.

How to Reduce Your Symptoms Once You Have a Cold Sore?

If a cold sore is already present, here are some tips for managing your symptoms.

  • Catch it as early as possible! When you use the available anti-viral treatments early, the sores are smaller, less painful, and short in duration.
  • Learn from your past. If you have had cold sores in the past that do not respond well to over-the-counter ointments like abreva®, talk to Dr. Chowning.  There are prescription medications that may work better for you.
  • Do not touch it! The blisters of cold sores should never be squeezed or popped.  This introduces bacteria to the sore and increases the risk of an infected sore.
  • Keep it clean. Do not put makeup over the sore.
  • Avoid kissing loved ones and sharing food and drinks.
  • Throw away chapstick used over an active sore.

Do You Suffer from Cold Sores? 

Talk to Dr. Chowning at your next visit about how you can reduce the risk of developing cold sores and how to treat them when they do occur.