The 6 Best Cold Sore Medicines of 2022

Frequently Asked Questions

• Does cold sore medicine work for canker sores?

  Cold sores and canker sores are two different things and so treatment is different for both.

  “Cold sores are blisters, caused by the herpes virus, that often form around the lips, although they can also form on the gums or the roof of the mouth. Once the blister pops, a scab forms,” explains Jin Lin, DMD, pediatric dentist with Hurst Pediatric Dentistry. 

  “Canker sores, in contrast, are small ulcers that appear inside your mouth, often on the inside of your cheeks or lips,” he continues. “They typically have a white, yellow, or grayish center and a red border. The exact cause of canker sores is unknown, but common triggers include stress and trauma to soft tissues in the oral cavity—for example if you bite the inside of your cheek.” 

  Most medications aimed at treating cold sores are antivirals in order to stop the herpes virus from replicating. This means they won’t work on canker sores, where there is no virus. 

  In addition, says Chris Airey, MD, Medical Director at Optimale, “most cold sore medicine you can buy without a prescription is not meant to be ingested and is intended for topical use.” So you can’t apply them inside your mouth. One notable exception is Zilactin, which is safe for inside your mouth. Its active ingredient is benzyl alcohol, which helps numb the pain of canker sores and cold sores, though it doesn’t treat cold sores in the same way as Abreva.

• Can you use cold sore medicine while pregnant?

  It depends on the medicine, which is why it is best that a pregnant person runs all of their medications past their OB/GYN. 

  However, “Abreva and Zovirax and Valtrex (two prescription cold sore options) are considered safe for pregnant patients,” says Todd Minars, MD, dermatologist with Minars Dermatology. “The FDA hasn't specifically evaluated the products for use on pregnant patients [but] research has been done to suggest they're more than likely safe.” 

  In addition, he adds “once a parent passes their 36th week of pregnancy these antivirals carry less concern for the developing baby.”

• How long does it take cold sore medicine to work?

  “It depends on the patient, their cold sore history, and the medication,” says Minars. But in general, topical OTC creams should cause you to show improvement somewhere between 72 hours to four days later. Sometimes, though, it can take a week or more. But in general, your OTC medication should speed up recovery by two to three days. 

  That said, according to Airey, "sometimes if medication is taken at the first signs of a cold sore, you can prevent a breakout entirely.”  

  Plus, while the healing does take time, some topical treatments can reduce your pain within just a few minutes, making you feel better even if the cold sore hasn’t gone away.