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Are Cold Sores Contagious?

Having a cold sore is bad enough, but worrying about spreading cold sores can make it even worse.

So how contagious are cold sores?

During the first 3 days after the blister appears, the virus levels are at their highest.  However, cold sores are contagious throughout their 7-12 day lifecycle until they fully heal.

If you have a cold sore, the following precautions will help prevent infecting others:

  • Avoid intimate contact, such as kissing and oral sex
  • When you have an outbreak, don’t share eating utensils or drinking cups, or personal items such as tooth brushes, face cloths, towels, razors or lipstick
  • Avoid touching the blister, and also incorporate frequent hand washing before touching other parts of your body to help prevent the spread of the virus
  • Consider using a POLYSPORIN® Cold Sore Healing Patch, which effectively covers the cold sore, contains the virus and helps to prevent the infection from spreading to other parts of your body or transmission to others

After the third day, the virus level begins to fall. The sore itself may remain for several days, along with other symptoms. Usually by this time the blister has stopped oozing or has crusted or scabbed over. Keep in mind that even though less virus is present, the virus can still be transmitted to others. 

Whether you pass the cold sore virus on to others or whether that cold sore virus ever becomes active in other people isn’t certain. Theoretically, anyone can develop a cold sore but some people, even after exposure, never develop one.  Others are highly susceptible.

Even if this means not everyone is at risk, it still makes a lot of sense to take precautions not to spread the virus.

It is especially important to avoid infecting newborns, seniors, or those with weakened immunity, as they may have a more severe reaction with sores that take longer to heal.