How long is someone infectious after a cold?

I am talking about a common cold, not something extreme.

  • 1
    This is too broad a question to answer. We need to know a) gender b) age c) other medical details d) time of year e) general environment f) what the strain of col is like. Every 48 hours, the strain of cold is different (which is why there is no vaccine). I don't believe anyone could answer this question.
    – Tim
    Apr 8, 2015 at 12:19

2 Answers 2


Tl;dr - More contagious at the beginning, much less at the end.

The "common cold" (or upper respiratory infection) is associated with over 200 different viral types1, and many times more than one virus is present. Because of this, there's probably no completely specific answer to this question, but it can be answered generally.

Rhinovirus-caused colds (which are a large majority of "common" colds) are typically contagious at the beginning, and are much less contagious after a few days2. You are most at risk of transmitting the virus to someone else for the 4-5 days after being exposed yourself3 - not necessarily when symptoms appear.

In other words, you can definitely be asymptomatic and still contagious. On the other hand, if you still feel symptoms after a week, the chances are much lower that you're actually still contagious.


1: Common Cold: Virology (wikipedia)

2: Incubation Periods of Experimental Rhinovirus Infection and Illness

3: When are colds contagious?


In general, a person first becomes contagious two to three days before their symptoms begin, and they remain contagious until all their symptoms have gone. So most people will be contagious for around two weeks.

Symptoms include coughing, sore throat, runny nose, sneezing, and fever which usually resolve in seven to ten days, with some symptoms lasting up to three weeks as the body fights off the infection.

Colds in younger children can last up to two weeks.

You should see your GP if your symptoms persist for more than three weeks.

Most colds get better on their own without treatment.


See also:

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