• Original Articles By Dr. Lavin Featuring Expert Advice & Information about Pediatric Health Issues that you Care the Most About

    How Long Do Colds Last?

    By Dr. Arthur Lavin

    The hope of course is one day, or less.

    Every time my nose gets sniffly, my throat scratchy, and a cough pops up, I initially pray that it’s just a passing thing, please not a cold.

    But if the cold clearly has hit, I then shift my pleas towards the clock, please let it be here only for a day.

    That happens, it is a real hope, but it’s not how it usually goes, and most of us now that from the hundreds of colds adults have had.

    Why Not a Day- the concept of the viral fuse

    The sad truth is that if you tracked the actual experience of a cold from careful diaries of thousands of children and adults, the answer always comes back the same- eight days.  That’s right, the average length a cold takes to come and go is one day over a week!

    Why is that, what cruel part of nature dictates that colds usually don’t last a day?

    The answer lies in what is physically happening when you have a cold.

    What is physically happening is that when a cold virus lands on your airways- those would be nose, throat, and/or lung- and gets to invade, it literally burns off the lining of that airway.  Literally.  A virus simply is a bit of genetic material wrapped in proteins that deliver it to the genes of your cell, where it takes over the cell forcing it to make zillions of copies, popping the cell and releasing zillions more viruses.  That chain reaction leaves zillions of our cells decimated.

    This is seen in any virology lab, where sheets of cells are exposed to a virus and then observed to be obliterated.

    So a viral infection is very much a burn.  Thankfully, in the case of colds, the burn is not very deep.  They can only attack the surface cells of the lining.

    Which brings us to the concept of the viral fuse.  Once a virus gets into a cell, say in your nose, it pops that cell then releases zillions of new viruses, many of which will infect the next door cell and pop it.  You get the idea.  From the initial spot, a small fire is lit, and burns all the tissue surrounding that spot.  Again, assume the first cell is in the nose, now that lit fire burns all the tissue lining the nose, and the fire then spreads to the throat, then the next door neighbor cells are the lungs.

    The fire only goes out once the viruses are vanquished, but that usually occurs once the full lining is burnt.

    So How Long Does this Take?

    Again, assuming it’s a typical cold, starts in the nose, then burns down to the throat and lungs, the whole process, a median of 8 days.

    That is, half of people with a cold will be sick for less than 8 days, and half for more than 8 days.

    Another way to look at this is the 95th percentile.  Studies have measured how long a symptom goes on for a cold before 95% of those sick stop having that symptom.

    Here are the intriguing, and sad, results:

    • Fever- 5 days
    • Sore throat- 8 days
    • Runny nose- 10 days
    • Cough- 25 days!

    (Again, what this means is that you have to wait 5 days for 95% of kids with a cold to no longer have a fever.)

    The real shocker here is the 95%tile for cough, you have to wait 25 days (!) for 95% of a million kids with a cold to be free of a cough.  Again, a cough may go away in 1 day, or 5 days, but 95% aren’t done with a cough until 25 days are past, nearly a month!

    But I clearly remember having a cold for only a day

    Sometimes our prayers are answered.  Remember the median says half of all people with a cold will be sick for less than 8 days.  And if 95% of people aren’t over a cough until after 25 days of being sick, that still means perhaps 2% of people will be over their colds very quickly.  If about 320 million Americans get a cold each year, that would mean about 6 million people will have very short colds this year.

    What can I take to shorten a cold?

    Again, sadly, nothing.  The virus once it hits burns.  There are only two ways to stop this process.  One, kill the virus.  Two, heal the burn.

    As you probably are guessing, no substance yet invented kills cold viruses.  The only exception are medications like Tamiflu, which only kill one type of cold virus, the influenza virus.  But this virus is only present during its season, and even during that time about 2/3 of colds are due to other types, that Tamiflu is powerless against.  Further, Tamiflu has little impact if you’ve been sick for 48 hours or more, works less well in children, and has potentially serious side effects.

    When it comes to healing the burn, we are no better at that today than healing real burns.

    It is useful when thinking about colds, to think of a burn.  If you unfortunately burned the back of your hand today, what could medical science do to make that burn go away in one day?  Of course the answer is there is no such intervention, it simply does not exist.  So, like burns, colds force us to wait til we heal.

    What about a whole season of colds?

    We see a very, very large number of children who seem to be sick all winter.  In nearly all such circumstances, this is true, but the result of having 3-4 colds in a row.

    Again, if we think about a child having 4 colds in a row, each with 7 days of wellness between them (it’s usually more like 2 days), and the median time a cold lasts is 8 days.  Then that child will be sick for 53 days, almost two months, just with those four colds.  And if two of the colds last more than 8 days (about half do), say 14 days, then your child will be sick for about 10 weeks with those 4 colds.


    1. Colds are like slow burning fires, creating a fuse that burns typically from nose to throat to lung, causing runny nose, sneezing, sore throat, and cough, with sometimes hoarseness or barking cough along the way.
    2. We all wish our colds and those of our kids would last no more than a day, but half of all people with colds will have one lasting over 8 days.
    3. It takes about 25 days (!) for 95% of kids with a cold to stop coughing.
    4. We don’t really have effective treatments to kill the viruses that cause colds.  You’ll know when we do, colds will vanish like other vanquished foes like smallpox and polio.
    5. Since there are literally hundreds of cold virus types, it is very easy for kids to get a bunch in a row every winter, causing the months of illness we often see.

    So, colds last much, much longer than we would like to (and therefore do) think.

    The only good news is that they always go away.

    Stay warm, stay well, keep comfy if you get a cold.

    To your health,
    Dr. Arthur Lavin

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