When Is A Cold Sore No Longer Contagious?
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When Is A Cold Sore No Longer Contagious?

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It starts as a tingling, burning or itching sensation, soon followed by blisters that begin to ooze: another cold sore has arrived. Unfortunately, the virus that causes cold sores is highly infectious. But for how long are cold sores contagious? Once the sore has scabbed over, your chances of passing on the virus decrease significantly.

What Causes Cold Sores?

A very common virus called herpes simplex virus type 1 (HSV-1) causes cold sores. After the first infection, the virus remains in the nerve cells forever. Triggers like exposure to sunlight, fatigue, stress or hormonal changes activate the virus, making a cold sore appear.

Sores usually break out on or near the lips. There's no cure for cold sores, but antiviral medications may reduce the frequency of outbreaks.

Why Are Cold Sores Contagious?

The virus that causes cold sores spreads through skin-to-skin contact, which makes it highly contagious. According to the National Health Service (NHS), cold sores are most contagious when the blisters burst, but they are contagious from the tingling stage until healed.

The virus can spread to other people through kissing or sharing utensils. Touching cold sores and then touching the eyes can cause serious infections and vision problems.

When Is a Cold Sore No Longer Contagious?

A cold sore becomes much less contagious after it has formed a scab, says the American Academy of Dermatology. The fluid-filled blisters burst around four days after the first symptoms appear, and by five or eight days into the process, a yellowish or brown scab forms that reduces the chances of infection.

The scab begins to flake and fall off between days nine and 12, and finally the sore heals two to four weeks after the onset of symptoms. However, the Mayo Clinic states that people can pass on the virus even when they don't have any blisters. What's more, many people who have the virus never show any symptoms.

How to Avoid Spreading the Cold Sore Virus

Good hygiene and avoiding close contact with others helps prevent spreading the cold sore virus while it's at its most infectious stage. Wash your hands often, and try not to kiss anyone or have intimate contact before the scab forms over a cold sore.

Don't share food or drinks or personal items like towels, razors or lip balm, and don't touch a cold sore unless you're applying medication. Wash your hands immediately afterwards. Additionally, people with active cold sores should avoid close contact with newborns and people who have weakened immune systems.

How to Heal a Cold Sore

Cold sores resolve naturally, but you can try to help speed up the process with antiviral medications. Creams or pills containing certain ingredients may heal cold sores more quickly than no treatment.

Pain relievers like paracetamol, ibuprofen or benzocaine can help reduce the swelling and pain of cold sores and lessen the temptation to touch them. Popping the blisters and picking away the scabs won't heal cold sores any faster, and it may introduce bacteria that infect the sore and cause long-term scarring.

For most people, cold sores are annoying but rarely interfere with their everyday lives. That doesn't mean you want to share your cold sores with anyone else! Take sensible precautions if you feel a cold sore is on its way or the blisters haven't scabbed over, and the chances are good that you'll keep the infection to yourself.


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This article is intended to promote understanding of and knowledge about general oral health topics. It is not intended to be a substitute for professional advice, diagnosis or treatment. Always seek the advice of your dentist or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment.