Can I Have Multiple Antivirus Programs?

Category: Anti-Virus

A reader asks: 'I have Norton Security on my PC, but I still got a virus. Is it a good idea to run more than one anti-virus program? If not, which anti-virus has the best protection against viruses, spyware, and other online threats?'

Is It Okay to Have Multiple Antivirus Programs?

Often when you buy a new computer, it comes with a trial version of Norton, McAfee or some other commercial antivirus software. When that free trial is about to expire, the program starts to nag you about upgrading to a paid version, which can be expensive. That's when some users start looking for a free antivirus alternative. There are some excellent free antivirus programs, but a common mistake is to install that freebie without removing the old one. Some users also think they'll be more secure if they install a second antivirus package.

In most cases, having more than one antivirus program running on your computer is bad news. Antivirus programs consume memory and processing power, as they scan the stream of data, emails, web pages and downloads that enter your computer. So it makes sense that having more than one antivirus scanner will slow down your computer.

But there's another potential problem... Sometimes antivirus programs can fight with each other, since they both want to be the final arbiter of good and evil on your computer. One might even think the other *is* a virus, and attempt to quarantine it. You may see slowdowns, lockups or experience random restarts. I actually tested this recently, installing AVG, Avast and Avira on my laptop. The result was a computer that slowed to a crawl. You could watch paint dry between keystrokes, and the process of uninstalling them took hours.
Multiple antivirus programs

My advice is to pick ONE antivirus tool and stick with it, at least until you decide to replace it with another. I've compiled a list of some excellent Free Antivirus Programs, which I use and recommend over the paid-for security suites on the market. If you want to study them further, check out the reports in my article Lab Tests Reveal Top AntiVirus Programs to see how various antivirus programs compare in terms of effectiveness.

Exceptions to the Rule

That said, let me introduce just a bit of tech talk, and explain the exceptions to my single anti-virus rule. There are three types of anti-virus protection: real-time, on-demand and offline. Here's a quick description of each:

The real-time variety we've been discussing so far protects against viruses and other threats as they arise. Your real-time anti-virus software is constantly scanning everything that enters your computer, as well as every program that runs. Examples are Norton, McAfee, AVG, BitDefender, Kaspersky and many others.

On-demand virus scanners are only active when you specifically launch them, to scan your hard drive for malware. Two of the most popular are MalwareBytes Anti-Malware (MBAM) and Spybot Search and Destroy. These are designed to co-exist with your real-time anti-virus software, and can sometimes catch things that have slipped through your first line of defense.

Offline anti-virus tools run from a bootable CD or flash drive, and will do a deep scan of your computer. While the offline scanner is running, both Windows and your primary anti-virus program are inactive. See Extra Security: Windows Defender Offline for more info on offline security tools.

So to be clear, YES, I recommend just one REAL-TIME security tool. Supplementing that with an on-demand scanner such as MBAM is fine, and is a practice I recommend. And for those situations where you can't start up your computer due to a virus infection, an offline scanner is what you need.

Which Antivirus Programs Do I Have?

If you're not terribly tech savvy, you might not even know which antivirus program is installed on your computer, if you have more than one, or none at all. To find out if you have antivirus protection, open Control Panel and click on Security Center. If there is a red light next to Virus Protection, you have no antivirus protection, and fixing that should be Job One. If you see a green light, you're good, probably.

Taskbar antivirus icons Now let's find out if you have one or multiple antivirus programs installed. First, check out the little icons in the taskbar on the bottom right of your screen:

Click on the little white arrow to expand the list if needed, then run the mouse pointer over each one without clicking. As you do so, the name of each program will appear in a little popup as shown above. Real-time anti-virus programs should clearly identify themselves. Look for names such as AVG, Avira, Avast, BitDefender, Eset, F-Secure, G Data, Kaspersky, McAfee, Norton, Panda, or Trend Micro. There could be others, but those are the most common and popular ones at present.

If you find more than one, go to Control Panel, Add/Remove Programs, and uninstall the anti-virus program(s) you don't want to keep. (Bear in mind what I mentioned about real-time and on-demand scanners above.) You'll need to restart your computer to finish the removal process. When you're done, make sure your remaining antivirus protection is up to date and run a complete scan to check for nasties.

Do you have something to say about anti-virus protection? Post your comment or question below...

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Most recent comments on "Can I Have Multiple Antivirus Programs?"

(See all 21 comments for this article.)

Posted by:

23 Apr 2013

Hi Bob,
While you make no mention of it, I think Microsoft's MSE (Security Essentials) deserves a mention. It, too, is free.
Also, Malwarebytes Anti-Malware(MBAM) has a Pro Version (paid-- about $15 or $20 for personal use) which does bring real time protection as well as scheduled scans. Does this make the pro version of MBAM a hybrid that can co-exist with your oter resident real-time Anti-Virus (meaning there were be two programs running and checking file access simultaneously, or do you think this is a bad idea?
I don't think MBAM Pro is considered to be a suitable solution as a single anti-virus product. MBAM's website has FAQs relating to making it coexist with major anti-virus products, so their position must be that you need both their product as well as an anti-virus.
Your thoughts?

Posted by:

Jerry B
23 Apr 2013

You recommend running only one real-time program. Malwarebytes Anti-Malware PRO (paid) -- which does real-time checking -- seems to co-exist quite well with the Avast (free) on my Windows 7 64-bit system.

Posted by:

23 Apr 2013

Good luck removing Norton. Not only is it a total waste of money but it leaves a lot of residual junk on your computer unless you go to it's site for the removal tool.

I've used Microsoft's Security Essentials and malwarebytes for 3 years now and have never had a virus issue. I recommend Ccleaner for cleaning the registry and cookies and walla...a good running computer at all times.

Posted by:

23 Apr 2013

I have 3 anti virus programs running on one of my computer. I keep an old version of Norton, which allows me to block banner ads and pop-up. I can specify what URLs I don't want to view their stuff. The other 2 anti viruses are over lapping, because I paid for them several months apart and I liked the features of both. When one runs out, I will just deleted it and keep the other one that is paid and just keep the other one.

Posted by:

24 Apr 2013

Hey Bob,
I have used Zone Alarm's Extreme Security in the past. I still have an active paid subscription to it, but it is not presently installed. Rather, I bought Webroot's Secure Anywhere full security package, which is in the cloud. Combined with either ZA Extreme or Webroot I run Malwarebytes (MBAM) Pro version, and both suites get along perfectly with MBAM. Webroot's cloud-based suite I found seems to be as effective as ZA. The main benefit is Webroot's cloud-based ability frees up a lot more resources on my PC, in which there is a very noticeable performance gain with speed of other applications to use. And too, Webroot's Secure Anywhere is always automatically updated at their server, so you do not need to check yourself. On a final note Bob, have you seen any reviews of these 2 security suites I've mentioned lately, as they are never included with all the others you have listed among the many other suites available. Thanks, Bill VS

Posted by:

Scott K
24 Apr 2013

I run a full scan with Avast every week. On the rare occasions it finds something, is it better to move it to the chest or delete it? Thanks

EDITOR'S NOTE: Probably safer to quarantine. If it finds a false positive, you won't lose your file.

Posted by:

24 Apr 2013

To the (persons) wanting to fully uninstal various anti-virus programs or any other software.
Try using the free version of Revo Uninstaller. It digs in deep into your computer and removes all sorts of "junk" that the regular uninstaller leaves behind.
I use it when I need to fully remove anti spyware that (to me) is not needed.

Posted by:

24 Apr 2013


I agree with you. The three applications you mentioned above is what I use and they work beautifully together in tandem.
This is in addition to Spybot: Search & destroy and the Comodo (stand-alone) Fire wall.

I have not had a conflict problem among them and I have used these for years!


Posted by:

24 Apr 2013

To the person(s) that have trouble uninstalling Norton (My opinion = Norton isn't worth it if it were free) Symantec, Norton's vendor, offers a free complete uninstaller. Find it at (NRT = Norton Removal Tool)
Most of the other big AV vendors have removal tools if their product gets munged by a virus. Google is your friend.
Revo is good, but a Vendor-supplied product-specific complete uninstaller is even better.

Posted by:

24 Apr 2013

I have two installed ... Avast Free and Malwarebytes Anti-malware. Avast free is running "real time". I also have MS Malicious Software Removal Tool (MSMRT). In most cases, it is ok to have more than one installed. It is, however, necessary to ensure ony one is set for real time scanning. I had AVG Free for awhile but got dissatisfied; especially when a new version update was released. And worse yet when a new upgrade was released; for example .. v8.4 to v9.0, pretty much (almost invariably) requiring a complete uninstall of the older version before installing to new version.

Posted by:

24 Apr 2013

Many (most?) anti-malware companies have their own official uninstallers and instructions on how to use them. Sometimes uninstalling through Control Panel leaves behind remnants that can interfere with a clean install of a new product. Singular Labs has compiled a list of popular uninstallers.

Posted by:

Bruce Houghton
24 Apr 2013

Another important item is to make sure your antivirus program is actually turned on to perform periodic scans. I am running Avast. It was updating several times a day, but I forgot to actually schedule the quick and full scans. I schedule a quick scan daily and a full scan weekly. BH.

Posted by:

Sharon H
24 Apr 2013

I've been happily using Avast and Malwarebytes for many years. Even the free version of Avast provides a very decent security suite, esp. for the home user. Malwarebytes seems to concentrate on other types of malware such as trojans for a well rounded approach. The combination of the two has never produced a conflict. Highly recommend them.

Posted by:

24 Apr 2013

To assure our full 146% I have to point out that 'walla' is actually a word with many meanings; none of them are what most people think thay are saying. On the other hand 'voilĂ ' is the word most people mean, roughly, "there it is" or "here it is". Feel smarter?

Posted by:

24 Apr 2013

Hi Bob,
Always, you provide great articles.
I am connected via Wifi Cable, so I know it provides its own firewall, but here are the ones I have installed on my computer and work great without any conflicts at all.
I have Windows Defender, MSE, and an all-in-one utility Advanced System Care Ultimate that has an AV/firewall working in real time.
I also use the Windows defender-offline.
I have never had anything compromise my computer in the last 2 years since going to those I use.

Posted by:

25 Apr 2013

Thanks Mike. I'm old and admit my bad on the walla booboo. I still have a clean computer.

Posted by:

07 May 2013

What's wrong with you guys? Why all this hassle? Ever heard of Linux?
I hate MS.

Posted by:

17 Oct 2013

One thing I don't see mentioned is that there are are a number of AV suites out there which incorporate multiple scanning engines in their design such as Coranti, Emsisoft, Qihoo 360, and many others.

In addition to the non real-time tools mentioned by the authors and by others, another Two free examples are:

Metascan Client - Run a quick scan of active processes and their associated libraries against 5 cloud based AVs as a quick check to see if any currently running processes may be malicious - A website allowing you to upload individual files and scan against 40+ engines, good for checking potential false positives, or suspicious files your local AV doesn't flag.

Posted by:

TJ Viktor
01 Apr 2015

Hi Bob,
Firstly I would like to thank you for sharing such a wealth of expertise and knowledge as you are graced with, allowing those of us less blessed with tech savvy-ness a means to catch up. I have been subscribed to you for a while now, & always find your articles to be of immense help, with answers to pretty much every question I've thought to ask.
Recently I've begun having my youngest son (11) read your (almost) daily articles, along with an older article daily; to generally increase his tech skills, and as part of our homeschool.
Thank you for taking our collective hands, and walking us through the simplest and most basic aspects so plainly, that even the dummiest of dummies can understand. Then with your dashing & heroic abilities to make the more obscure knowledge accessible to all, you bridge us to tech wisdom.
Thank you Bob :)

Posted by:

15 Sep 2015

Well really you have Windows Defender, Windows Firewall, and also MRT (Malicious Software Removal Tool. Already Installed on Windows Computers so you really don't need more "AV" Products or firewalls/MRT's. Because Microsoft Provides those with windows. Although Microsoft came out with MSE (Microsoft Security Essentials) You really don't need anything. Also MSE Turns off Windows Defender.

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