When does a cold sore stop being contagious?

A cold sore goes through five stages (level of contagion) :

Cold sores are contagious at all stages with stage 3 being the most infectious due to the opening of blisters that ooze infected fluids.

Cold sores are contagious from the initial symptoms to the resolution. From Day 1-2, cold sore blisters are full of virus that spreads through saliva, skin-to-skin contact, or by touching an object handled by someone infected with the virus. You can spread the virus even when you do not have any apparent symptoms of a cold sore yet. However, this is much less likely than if contact occurred when a cold sore is present. The fluid in the blisters contain the virus, therefore cold sores are most contagious when the blisters ooze. The first cold sore episode will generally occur two to 20 days after being in contact with an infected person.

Cold sores, caused by a type of virus called herpes simplex type 1, are contagious until they completely go away, which usually takes about two weeks. Cold sores are the most contagious when fluid seeps out of the sores. Once the sore has scabbed over, the risk of passing on the virus decreases significantly, but that does not mean it is no longer contagious. Your scab can be broken while eating or smiling, and the fluid can leak out.

Herpes can be passed on more easily when you are having an outbreak and active sores or blisters are present on the skin. However, the herpes virus can still be spread even if there are no signs or symptoms.

Adults who have a cold sore should take care not to kiss babies or let babies touch the sore for two reasons.

1. Cold sores are usually pretty harmless, but they can become severe in people with not yet fully developed immune systems. The immune system usually protects the body from infection. A person with a weak immune system is likely to get more severe infections than most other people. In that context, the cold sore virus can be dangerous for babies less than 6 months old.

2. Once the baby has been infected, they will be prone to cold sores for the rest of their lives

The same precaution must be taken with people affected by HIV (human immunodeficiency virus) and people suffering from cancer and treated with chemotherapy. It is, therefore, important to remain particularly vigilant with these people and take steps to avoid infecting them with HSV.

You should minimise any contact with the sores. Always wash your hands after contact with a cold sore to avoid spreading the virus from one site to another, such as the eyes, nose, or fingernails.

Until the cold sore blisters and scabs have completely gone away, you have to protect yourself and other people from infection. Airtight and watertight treatments such as COMPEED® cold sore patches help prevent the virus from spreading to another area of your body as well as protecting others.

While there are many ways to contract the cold sore virus, we have outlined the most common below.

Until the cold sore blisters and scabs have completely gone away, you have to protect yourself and other people from infection. Airtight and watertight treatments such as COMPEED® cold sore patches help prevent the virus from spreading to another area of your body as well as protecting others.