Helping people with computers... one answer at a time.

While no single anti-virus program can catch all viruses, running more than one anti-virus program can cause problems. And it also might not help.

I keep reading that no one anti-virus protection software can capture all viruses, etc, and that multiple programs should be used. However, for just about every program I have tried, not only can you not use other anti-virus programs, it's nearly impossible to disable or even remove them totally. Plus some of them disable critical computer functions.

How can one use multiple anti-virus programs? Any examples?

The reason you keep hearing people like me say that you can't rely on a single anti-virus tool to catch everything is more about education than anything else. We're typically not trying to get you to run more than one.

But, beyond that education there are a few practical guidelines and things you can do that do involve more than one anti-virus program.

I'll look at both.

As you've said there is no single anti-virus program that you can run that will absolutely be guaranteed to catch every virus.

"There's no single tool or combination of tools that will catch absolutely everything."

More so: even if you were able to run every anti-virus program known to man - there's still no guarantee that the combination will catch every virus. There's no single tool or combination of tools that will catch absolutely everything.

That's the education part.

The goal is not to run more than one to catch everything simply because you still can't know that you've caught everything.

The reason I and others keep telling you that no single tool (or combination of tools) will catch everything is to remind you that you are the weakest link and must remain on guard.

You can't just assume that your anti-malware tools - whatever they are and however many you run - will keep you completely safe. In fact, making that assumption will probably make you less safe. You need to be aware of your own behavior on the internet - things like opening attachments, visiting malicious web sites, allowing malicious downloads - and keep that all in mind as an important part of internet safety.

On top of having good anti-malware solutions of course.

So what can you do with respect to multiple anti-virus solutions?

You can have only one "real time" scan active at a time. That means only one anti-virus package can be scanning the files you save as you save them, your downloads as you download them, and your emails as you receive them. Any attempt to have two or more anti-virus tools trying to do this at the same time will likely cause slowness, conflict, crashes and most commonly false positives.

Since most of the major anti-virus tools enable real time scanning by default they will often check at setup time to see if other packages are installed. What they do varies, but it can range from nothing to dire warnings (that many people misinterpret as errors) to actually refusing to install.

Many tools will peacefully coexist, provided you have real-time scanning turned off in all but one.

Why, then, would you want more than one if it's not also scanning what's happening?

There are two approaches to using a second anti-virus program:

  • You can run as many on-demand scans as you like. An on-demand scan scans not what's happening, but rather scans the files already on your hard disk. You might have program "A" scanning in real time, and then schedule program "B" to do a full scan of your hard disk every night. This way you get two (or more) different anti-virus programs monitoring your system on a daily basis.

  • You can run an on-demand scan if you have a concern. Let's say you just downloaded something and your machine started "acting funny" - perhaps a virus that your real-time anti-virus software didn't catch. You can manually run on-demand scans from other anti-virus tools to see if perhaps that's the case.

So you can, in fact, run multiple anti-virus tools; you simply have to do it in the right way so they don't conflict with each other.

My recommendation?

  1. Pick a good, primary anti-virus tool and have it monitor real time if you like. (As well as an anti-spyware tool and a firewall.) I'm not a fan of most all-in-one packages, so typically that means you'll be looking for individual programs.

  2. Remember that no single tool or combination of tools can guarantee complete protection. You must still assume responsibility for your online safety by understanding what is and is not safe, and behaving accordingly online.

  3. Don't worry about a second anti-virus program until or unless you suspect a problem has gotten past the much more important points 1. and 2. above.

Article C4304 - May 8, 2010 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

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18 Comments
thomas mitchell
May 8, 2010 10:59 PM

I run avast as my resident scanner.I also run scans with windows defender and malwarebytes.On Friday i noticed my cd rom would not recognize any cd placed in it.A search on google turned up information on a virus that infects the driver for the cd rom.I ran a scan with both anti-virus programs and came up with nothing.I then downloaded superantivirus and ran a scan,this turned up 587 tracking cookies and one other malware. These were quarentined and deleted. This cleared up the problem with the cd-rom.

Jeffrey
May 10, 2010 8:29 PM

Thomas, what happend to you was most likely a virus, but please be aware that there are many more things that can affect a CD-Rom's ability to read disks, some are known issues with windows (Microsoft has a fix for the one that comes to mind at their website) and others are hardware related. We want to make sure that those reading your comments are aware that not all issues are virus related.

Bob
May 11, 2010 1:42 AM

I run Avast on my home computer for viruses, and regularly check / protect my system with Search & Destroy.
As an additional safety net, I sometimes use the online scanner Housecall, from Trent Micros.
I'd rather use several 'free' solutions - knowing that you cannot be 100% sure makes paying for it seem hardly worth the money.

Tom
May 11, 2010 8:19 AM

This is one of the many reasons...I switched to a Mac!

I'm not trying to compare the two....all I know is that I don't get trojans and malicious junk anymore.

End of story for me.

Thanks

Quilljar
May 11, 2010 8:58 AM

One useful action is to sign up to a newsgroup like
alt.comp.anti-virus and keep up to date with the anti virus community. Also, since going over to Windows7 I have started to use Microsoft's own Security Essentials. I have installed Immunet(free) which is in the Cloud and can therefore be run alongside any other AV program. So far I have been completely free of any nasties for about three months now.

Ed Beecher
May 11, 2010 9:00 AM

We have been using the following for 4yrs with minimal problems (win xp)at our repair center: SpywareGuard, AVG 9.x, spywareBlaster, Spybot Search and Destroy. We also use CCleaner and Defraggler. All freeware. www.crc.org

Bob
May 11, 2010 9:07 AM

I have found a wonderful combination which I would like to share. My operating system is Windows XP Professional (32bit)-SP3. My Security system consists of the following: Avast free, ThreatFire, Spamfighter, Spywareblaster, SuperAntiSpyware(professional), Malwarebytes' AntiMalware, Microsoft Security Essentials, Advanced SystemCare, and Hijack This. I use Avast for the resident scanner, ThreatFire, and Spamfighter simultaneously. Advanced System Care is used weekly and the others are used as needed, usually once a week. If I get in trouble, I use HijackThis. I sometimes use Spybot if I find a real problem. So far, things are running smoothly, no crashes, the speed is affected a bit, but it's worth the wait for me. Hope this helps!!!

Michael T
May 11, 2010 9:10 AM

This article was very appro for me as I just completed doing battle with the mighty Symantec Corporation and my three infected home computers. I trusted implicitly my internet security to Symantec's newest offering Norton 360 Version 4 and I hope I never make that mistake again. In short my three home computers were infected and was using my email contact list to really embarass me. Whatever infected my PCs was sending emails on my behalf(and name)with a link to a website selling Viagra. Emails were sent to both of my daughters and to many of my business associates including a member of the Royal Family in Sauadi Arabia. I am an IT professional of 28 years but, for three days in early April 2010 I was embarassed and humiliated. While all of this was happening Norton 360 was reporting my machines as being protected. I had the big ole green "Protected" indicator rigth there on the desktops. Protected from what I asked myself. In the end, after raising bloody hell with Symnatec --I took my isssue straight to the top to Mr. Enrique Salem President and CEO of Symantec-- they are refunding my purchase price and now I am eavaluating a different approach to managing my internet security. I must give Symantec credit for their response to my issue, they did right by me. What really happened? Well it was a cobination of many things and this is not the proper forum in which to elaborate. Just note this one fact. If you use a Web based email client --such as Windows Live Mail-- most AV programs cannot detect malware with their email inbound/outbound mail check routine because most likely your email is stored on the providers server not your PC.

Me
May 11, 2010 11:06 AM

I use one antivirus for realtime scanning. The secondary one I run at least once every second week or whenever I think I picked up something. I've only had one virus infect my computer, and it was technically not a virus but a rogueware. (Which is why just antivirus is not enough.)

On the other hand, my mom's computer kept getting malware. I told her to install an antivirus other than her outdated version of Norton and then she complained that the computer was all slow and acting funny and stuff. Turns out she installed another realtime antivirus on top of it. I told her to uninstall one and she kept Norton (*sigh*). Since I installed Mozilla Firefox and hid the icon to Internet Exploder (not a typo) it's cut down on the viruses a bit, though. However, I have to constantly remind her not to install those 3D screensavers...

paul
May 11, 2010 1:54 PM

i have found that NOD32 is the greatest all in one.. i havent had a problem of any kind since getting it over 2 yrs ago. i use advanced systems care to clean this pc up a little and also Malware bytes anti malware fromtime to time but it has never found anything. nod32 is that good. also use cc cleaner from time to time but just cuz i can. lol. i trust NOD32 explicitly and would have no other. those i know who also have it swear by it also

Jim H
May 12, 2010 3:13 AM

Isn't using multiple programs like this a waste of RAM since many run constantly in the background? It seems that some antivirus software is changing the way it looks at what is happening on the computer, monitoring behaviors of programs that are installing and alerting when something suspicious is happening. I use Norton products and even though I tried other security suites after Symantec solved the resource hog problem I immediately went back to them. I know that twice it alerted me when utility programs I downloaded tripped an alert that they were trying to access areas they shouldn't have. Install progress was halted and the files were quarantined. They had passed an initial scan although the security report indicated little was currently known about them. I also have an anti spy-ware/spam-ware program installed I run occasionally to double check. The truth is I have never seen anything come up from it or other antivirus, spy-ware or similar programs when I run scans remotely. My installed Norton product apparently deals with them quite well. I regularly run port scans at Gibson Research, grc.com, to make sure my ports are running stealthed and they all are. His site is an excellent resource for security information. Many years ago I had the misfortune of once catching a virus when it was still in the wild. It was a maddening few days until it was discovered and a learning experience for me because I didn't previously know such things can end up in the system restore files which at the time were omitted from virus scanning by default. It wasn't a fun experience, but fortunately, no permanent damage was done and no information was lost.

John Tarr
May 13, 2010 5:02 AM

I'm glad to see that Leo provided some good advice on this matter. I've been repairing computers for 10 years and the vast majority of the problems that my customers have had with their computers are self-inflicted by bad behavior like opening email attachments in unsolicited emails or downloading a "recommended" program from an unfamiliar website. Everyone has their own preference as far as what programs best protect their computer from threats. My cocktail as I call it, is AVG Free for viruses protection and Spybot S&D for Malware and Spyware. Both of these programs constantly monitor my system and don't slow it down. To compliment these programs, I use Free Download Manager which helps identify malicious sites and religiously run CCLeaner to keep my registry healthy, especially after downloading or installing anything from the internet. By the way all of these programs are free.

Gregory West
May 14, 2010 5:47 PM

Now you can run 2 anti virus programs at the same time as long as the second one is the new: immunet.com - I have it on 6 computers and it works great. Read the reviews here at Cnet:
http://download.cnet.com/Immunet-Protect/3000-2239_4-10965674.html

Emilio N
May 19, 2010 2:31 AM

You're spot on with the multiple anti-virus dos and don'ts. The same is the case with spyware as well.
I believe one good solution would be do use a virtual machine and route all internet access through it. This radically reduces the chances of catching an infection.
Any recommendation for a decent free sandbox or other virtual machine software?

ariel
May 21, 2010 8:33 PM

I love the way you predict the question I am about to ask as I am reading along. This is your gift that takes your teaching a level above. Thank you.

David H.
January 11, 2012 11:13 AM

Hey guys,

I agree that running multiple antivirus programs on your computer isn’t a great idea, but there are a few ways that you can still check the scan results of multiple antivirus engines. I’ve found these free tools to be pretty helpful:

1. You can do a quick scan of your running processes and memory with 5 antivirus engines using the MD4SA demo (http://www.opswat.com/products/metadefender-for-secure-access)

2. You can upload files to scan with many antivirus engines using Metascan Online (http://www.metascan-online.com)

Hope these help!

Tony Sterenberg
October 15, 2012 7:00 PM

I have been running for at least the last two years several anti virus programs. Some I paid for. I deleted most of them I do keep some but what I found out. Run the scan and it will clear all the problems. Run it again and it shows more problems. Run it again and you have the same number of problems. Now I deleted all the virus programs. Everytime I am on the computer I make a back up. All my documents are on a disk and all my pictures. I have not have a problem since. At no cost I run my disk with Avast. No problem reported. My computer is old but it works. Tony

Tony Sterenberg
October 15, 2012 7:18 PM

If you become and you will an oldy like me. The most important thing is to keep communication open. That means be able at an older age to communicate with the ouside world because you can't run to the post office anymore but you want to keep your e-mail going. You do not hear well and although you understand e-mail you do not understand the technology or not as well. We seniors are the people who saved some money. We do like e-mail (the old post Office) but if a technical problem arises most of us Seniors do not know what to do. So we give up because your technology is not simple enough. My conclusion You and everybody else in the technology field threw a 4 Billion Dollars away. I could help and I would. But I do not even get a respond back.
Tony Sterenberg

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