How to Treat a Cold Sore

You tend to feel them at the edge of your lip before the painful bumps emerge. The cold sore then follows a predictable cycle: pop, ooze, scab over, and eventually heal. For many, this process begins anew every few months.

Cold sores can develop after infection with the herpes virus. They’re commonly caused by a version of the virus known as HSV-1, which is different from the version that typically causes genital herpes. 

HSV-1 is very contagious. About half the people in the United States have it. You can pick it up through close contact with someone who is infected, such as through kissing or sharing food or drink. 

And it’s not always easy to tell if someone is contagious. People can transmit the virus without a visible cold sore.

If you do become infected, it could take years before you develop a cold sore, or maybe you never get one.

Once you have an outbreak, though, the virus can cause cold sores throughout your life. The frequency varies from person to person; some get multiple cold sores a year, while others get them once a year.

Here’s a guide to treating cold sores, and whether they can be prevented.

What’s the most effective cold sore treatment?

Most cold sores will resolve on their own in about a week.

But taking an oral antiviral medication, such as famciclovir, acyclovir, or valacyclovir, can decrease the pain and shorten the time for healing, especially when it’s taken at the first sign of sensitivity around your mouth. It might even prevent the bump from forming at all.

If you get six or more cold sores a year, you may be a candidate for something called suppressive antiviral therapy, which entails taking an antiviral medication daily to reduce the number, severity, and length of outbreaks. This therapy could also reduce your risk of spreading the virus to others.

Many over-the-counter topical treatments claim to heal cold sores quickly, some in as little as a couple days, but doctors generally don’t recommend them because topical medications are less effective at treating cold sores than oral antiviral medications are. This is because topical treatments don’t reach the nerve cells where the virus lives, so they can’t stop the virus from replicating.

Topical medications also don’t heal cold sores as quickly as oral antiviral medications.

But some over-the-counter steroid and numbing creams can help reduce pain while cold sores heal. Pain relievers like acetaminophen and aspirin are also effective.

It can be helpful, as well, to avoid eating or drinking anything acidic, which can make cold sores sting.

Can cold sores be prevented?

While individual cold sores will heal, HSV-1 is a chronic infection for which there’s currently no cure, meaning you’ll always be at risk for future outbreaks.

That said, if you know your outbreaks are prompted by certain triggers, you can try avoiding them. If exposure to ultraviolet light, for example, is a trigger, try wearing a lip balm with an SPF of at least 30.

Researchers are exploring therapies that alter the DNA of the virus in your body. A 2024 study resulted in the removal of 90% of the herpes virus involved in cold sores in mice injected with gene editing molecules. The authors of the study concluded that gene editing could potentially contribute to a cure for oral and genital herpes, but more research is needed.

For now, the only way to prevent cold sores is to avoid contracting oral herpes in the first place – a daunting prospect given how widespread it is.