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What Triggers Cold Sore & When Does A Cold Sore Stop Being Contagious?

Cold sores are tiny, fluid-filled blisters which mostly appear on or around the lips and mouth. As cold sores are contagious, it is important to know about them in detail. In this article, we look at what are the symptoms of cold sore, what triggers cold sore, when does it stop being contagious and its treatment?

Cold sores can appear on their own or in small clusters. The blisters often break, creating a scab which eventually falls off. They are caused by the highly contagious herpes simplex virus type 1 (HSV-1). One can have this virus in their body, and spread it too, even when they are not having any cold sore symptoms. Cold sores are contagious until they get completely healed and can even spread when they have scabbed over. This entire healing process usually takes about 2 weeks. Let us understand more about what triggers cold sore and when does it stop being contagious.

What Triggers Cold Sore?

What Triggers Cold Sore?

Once a person contracts HSV-1, it remains in their body for life. This virus stays dormant in the nerve cells until its reactivation is triggered. In order to understand the condition better and to be able to prevent or manage it well, you must be aware of what triggers cold sore. The common triggers for reactivation of HSV-1 causing cold sore are fatigue, stress, sun exposure, fever, infection, hormonal changes, physical injury, or surgery. The individual can still pass the virus to other people even when it is dormant.

While some people with HSV-1 infection never have any symptoms, other infected individuals do experience symptoms like fever, headache, tingling sensation, swelling, soreness and pain in the affected region, sore throat, and difficulty in swallowing. Some may show symptoms only when some factors trigger cold sore.

When Does A Cold Sore Stop Being Contagious?

HSV-1 spreads through close contact with the saliva or skin of an infected person, through acts like kissing, oral sex, or sharing towels, personal items and utensils. The virus can even enter the body through a break in the skin, like a small cut. The fact that the virus spreads or because it is contagious, it is necessary to take the necessary precaution. An important question to plan protection is when does a cold sore stop being contagious?

Most adults generally get exposed to HSV1 by the time they turn 50. Reactivation of HSV-1 tends to decrease after the age of 35 years. Around 10 % of HSV1 infected people develop cold sore within 1 to 2 week of its activation. Cold sores are actually contagious from the time symptoms like tingling or itching around the affected area first felt. The sores remain contagious until they get healed completely and go away. But they are however most contagious when they rupture, i.e. when fluid begins to ooze out of the sores. Scabbed cold sores are contagious too, as the scab can break and the fluid can leak out even when a person talks, eats, or even smiles.

Any exposure or contact with an infected person during this period can cause spread of infection, while after this period it may stop being contagious.

How to Treat Cold Sore?

There is no way of eliminating HSV-1. However, there are many ways through which its symptoms can be managed, which is the only way to treat cold sore. The healing process of cold sores can be accelerated by taking prescription antiviral medication. These medications are available in pill or cream form. Some patients with severe HSV1 infection may need to take injection of antiviral medication, as medically advised. Some common antiviral medications for cold sores are valacyclovir and acyclovir. Over-the-counter drugs, like docosanol, can also be used to heal cold sores. Redness and swelling can be reduced by applying a cold compress or ice cube to the affected area. Non-steroidal anti-inflammatory drugs, like ibuprofen can help to decrease inflammation.

How to Prevent the Spread of Cold Sore?

While an infected individual would always be able to spread the virus, they are most contagious when they have an active cold sore. It is commonly seen that it stops being contagious after 2 weeks, but during the infective period, prevention of spread of infection is necessary. To prevent the transmission of HSV-1, the patients should avoid establishing close physical contact, like kissing or having oral sex, until the sores get completely healed. They should be extra careful around babies, elderly and people with weakened immune systems, as both are extremely vulnerable to infection. The infected person should not even touch the cold sore unless applying a topical medication.

They should also avoid sharing items, like their eating utensils and cosmetics, with others.

As a part of protection from this infection, being aware of what triggers cold sore and when it stops being contagious is vital. With this information at hand, one can take the right steps and seek medical advice as appropriate.


  1. Mayo Clinic – Cold sores: https://www.mayoclinic.org/diseases-conditions/cold-sore/symptoms-causes/syc-20371017
  2. Centers for Disease Control and Prevention (CDC) – Cold Sores (Herpes Labialis): https://www.cdc.gov/std/herpes/stdfact-herpes-detailed.htm
  3. American Academy of Dermatology Association – Cold sores: https://www.aad.org/public/diseases/a-z/cold-sores-overview

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Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:August 5, 2023

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