How Long Is a Cold Sore Contagious?

Reviewed on 5/9/2022
Woman with an oxygen mask on her face
Cold sores are usually contagious for up to 15 days, from the first warning tingle until they have completely healed.

Cold sores (also called oral herpes or fever blisters) are painful blisters that form on or near the lips and inside the mouth. 

Cold sores are contagious from the first warning tingle until they have completely healed. The herpes virus that causes cold sores spreads more easily when sores are present, but it is also possible to spread the virus when a person has no symptoms. 

Cold sores are usually contagious for up to 15 days. They are most contagious when the blister bursts. Cold sores are generally no longer contagious once all cold sore symptoms have cleared, including the blister and any scabbing.

Cold sores are not the same as canker sores. Canker sores are also painful red or white sores that develop in the mouth and on the tongue, but they do not usually blister or form scabs. 

What Are Symptoms of Cold Sores?

Tingling, pain, burning, or itching on the lips may occur about a day before cold sores erupt. 

Symptoms of cold sores may include: 

  • Painful blisters on the lips, mouth, throat, or nose
  • Scabs that form after blisters open
  • Mouth and throat pain
  • Neck swelling 
  • Feeling ill (malaise)
  • Fever
  • Body aches

How Do You Get Cold Sores?

Cold sores are usually caused by the herpes simplex virus type 1 (HSV-1), transmitted from person to person through kissing, sharing eating utensils, or other types of close contact.

People who give oral sex to people with genital herpes can also get cold sores on their mouth.

How Do You Get Rid of Cold Sores?

There is no cure for the herpes virus that causes cold sores, but the majority of symptoms tend to occur during the first few years following infection. After that, the virus causes mild symptoms or none at all. When the virus is active, medications can help reduce and prevent symptoms.

Most people need treatment the first time symptoms of cold sores occur. People who have previously had cold sores or people who have mild symptoms may not need treatment.

Treatment for cold sores may include:

  • Antiviral medications
  • Antiviral topical ointments or creams
    • Wash hands with soap and water before and after applying topical treatments and dab the cream or ointment on lightly – do not rub it into the sore
      • Acyclovir (Zovirax ointment or cream)
      • Penciclovir (Denavir topical)
  • Pain-relieving pills and gels that go on the mouth, some of which may be available over-the-counter (OTC)
  • Home remedies 
  • When you have a cold sore, avoid: 
    • Kissing people 
    • Oral sex
    • Touching the cold sore, aside from applying topical treatments
    • Sharing eating utensils
    • Eating salty or acidic food if it aggravates the sore
Reviewed on 5/9/2022
Image Source: iStock Images