How contagious are cold sores?


Your body is feeling run down and you start to feel a cold sore emerging. You don’t think much of it, because how contagious can they really be? Unfortunately, these painful blisters are very contagious and should be treated carefully.

What is a cold sore?

A cold sore is a common term used to describe the herpes simplex virus when it’s located on the lip.

What causes a cold sore?

Herpes simplex virus (HSV) is responsible for causing cold sores. Generally, a cold sore can be caused by both HSV-1 and HSV-2. However, if it’s on the lips, it’s more likely caused by HSV-1.

How can it be passed from one person to another?

A cold sore can be passed knowingly or unknowingly. Generally, there are sensations (tingling, burning, pain) which precede the actual bump on lip. This bump can rupture and transmit the active virus. The virus can be spread by sharing utensils, cups, lip sticks, lip balm, as well as through kissing or oral sex.

The old belief that once there’s a scab there’s no longer any risk of infection is not true. The virus can still shed from the scab. Items shouldn’t be shared until there are no symptoms of pain, burning, tingling or discomfort at the site.

How do you treat a cold sore?

Oral antivirals at the onset of cold sore symptoms can decrease the duration of the virus. If you experience recurrent episodes of cold sore outbreaks, daily medications may be considered.

Over-the-counter cold sore medications, including topical treatments, may help expedite the conclusion of an episode. Vitamins like Lysine may also be helpful in reducing the number of episodes.

Tips to avoid giving or getting a cold sore:

Don’t share anything. Unfortunately, the virus can be transmitted even if the carrier doesn’t know they have it. If you know someone has the virus, avoid kissing, sharing utensils and cups, and oral sex. Also, avoid triggers such as direct sunlight and stress.

Desmond Shipp is a dermatologist at The Ohio State University Wexner Medical Center.