Why Shouldn’t I Install More Than One Antivirus Program At A Time?

If you are the go to computer guy in your family or your circle of friends then you are sure to have had this happen to you.

It is late at night or early in the morning and you receive a phone call; it is from a family member and they are having a problem with their computer.

The system will not run right and the antivirus that they have installed is not working.

“Okay, this is not a problem” you think to yourself, “I have seen a virus that is able to disrupt the antivirus on someone’s machine before.”

So you start to give them instructions on how to get rid of it but, unfortunately, the technique that you are describing to them is not working.


After a bunch of investigative work you come to find out that their computer has more than one antivirus program installed on it and they are blocking each other out.

This is more common than people think and is something that you must be aware of.

Why Is Running Two Antivirus Programs At The Same Time A Problem?

We as humans naturally think that the more of something that you throw at a problem, the better off it is going to be.

That is not always the case.

There are certain times when doing too much can be just as big of a problem as doing too little.

Installing more than one antivirus on the system is one of those cases.

Some people think that since the antivirus software that they use is not able to pick up everything then they should install a second one, or others do not know any better and they get an alert telling them that they need this software to protect them and they install it; they do not realize that they already have a antivirus solution already installed.

Antivirus software is installed differently to other software on the system.

It must be installed with administrator privileges because it must be able to get to certain sensitive places on your system.

If it is not allowed to do this then it will not be able to go after the bad guys effectively.

So when you have two antiviruses installed they are going to do one of two things – they are either going to block each other because they will use or scan the same process at the same time or they will try to eliminate the other antivirus software on your system since the antivirus software has some of the same signatures of the viruses that you are trying to fight.

It needs these signatures to be able to recognize the bad software on the computer.

When you are installing a piece of antivirus software on your compute, make sure that it is the only one.

If not then your system might become inoperable and, ultimately, infected.

About Lee Munson

Lee's non-technical background allows him to write about internet security in a clear way that is understandable to both IT professionals and people just like you who need simple answers to your security questions.


  1. Matthew Miles says:

    I’m not sure if I have two antivirus’ installed at the same time. I ran e tech check from McAfee and it said I did. I have advanced system care but not the paid version and i dont think it comes with an antivirus , or at least there are no settings for it. Now, I also have the IObit anti-malware program that came with asc and I’m thinking that maybe that is the issue since it actively scans for malware. Any ideas folks, i don’t want to be left in the lurch here.

    Im going to uninstall and test, i will reply with results.

    Thanks for your efforts in advance

  2. I can’t believe the idiots that don’t pay heed to IT Professionals & run more than 1 antiviral programme at a time. They will fell it in their pocket sooner or later. Sighhhhhhhhhhhhhhhhhhh……………………..


  4. we have 3 computers. our (family) desk top hp pc, my wife’s tosh laptop, my hp netbook. i have norton 360 on all 3.
    i went for norton coz it seemed to have best reviews, most fave feedback etc. top performer, yet still only 85% effective….?
    however, a couple of recent incidents eg. my netbook frequently saying norton & firewall switched OFF, when they were most def ON.
    made me wonder about extra av, so activated windows essential on all 3.
    so far, so good. all running fine, everything tickety boo.

  5. Kaspersky is better than AVG by a longshot. Also having 2 antiviruses can conflict issues with registries, and both antiviruses may come to a stalemate over who scans what file, ergo the file is left untampered or potentially damaged(not that likely). The registries can also make the anti-viruses ineffiecent. So who ever is using the computer should come to a decision over which to keep and which to lose. It’s not really a issue having 2 but can result in poor performance and several errors

  6. I dont know what the fuss is all about.. Or maybe i just dont know as much about computers as you guys but im running two seperate scans with two diffrent anti virus programs as we speak. And it works just fine. I wanted to delete one of them so i sort of ran a comparison scan of the to see which finds more infections on my laptop. Kaspersky found 2 and Avg found three.
    And they work just fine… Together.

  7. Yeah its exactly right.

  8. I was one of poor damaged people who thought I could put two free antivirus programs on my PC because they didn’t offer full support like a paid so if there were two then surely they would equal the one paid. Oh, how it is not so lol. I certainly learned my lesson. I prefer Avast! Paid.

  9. Well, well, well; in this day and age still “looking for desktop backgrounds with some flesh…” IMNSHO tells a clear story of immaturity and recklessly careless computing behavior: Neither McAffee SiteAdvisor nor WOT and likely using IE.
    Let them go do it, I cn handle a few more clean-up jobs, Ha ha.

  10. Well now lets see about this one.
    I know that a paid version of a AV program will not take having another AV program downloaded on the same computer, that a fact.

    But,, i ran 2 free versions on the same computer for years with no problems,, this was okayed by a computer tech. Now why did they work with no problem – simple, neither was active till it was used, of course this wasnt the safest thing to do since the AV programs wouldnt block anything an you would find a virus only by actually running one of the AV programs.
    Yes after a long time of trying it out i no longer do it, with newer products an other security programs out there i just no longer see the use in doing it.

    • I can’t believe you had two antivirus programs that were manual scan only – did you pick up any viruses whilst you had that configuration Dave?

      • Just once an it was my fault entirely.
        I learned not to look for backgounds/screen savers real quick on the web.

        • ha ha, thats exactly how my boys keep on picking up malware… they do like those wallpapers that show a little bit of bare flesh!

          • lol,, i wasnt looking for one of those kind,, but it sure taught me those sites to search for backgrounds/screen savers are not the best places to go to.

          • I learned that lesson many, many years ago!


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