You should only run a single antivirus application at a time, but none of them are perfect. Some antiviruses may catch malware that other antiviruses miss. Luckily, you don’t just have to rely on a single antivirus program.
The key to using multiple antivirus programs is running a single antivirus as your main background protection and running another scanner occasionally – say, once a week – for a second opinion.
If you have a suspicious file, you can also quickly scan it with in 46 different antivirus programs at once using a website.
Most antivirus programs are designed to be the single security solution for your computer. The antivirus has a background, always-on scanning feature that’s enabled by default. When you download a file, load a program, or access a website, the antivirus keeps an eye on everything and ensures it doesn’t match a known threat.
This works fine as long as you only have a single antivirus running at a time. These programs hook deep into your Windows operating system and are not designed to work together. In a best case scenario, running multiple antivirus programs at once could result in degraded performance. In a worst case scenario, the programs could interfere with each other and cause system crashes.
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However, no antivirus program is perfect. Some antivirus programs may miss problems other antivirus programs will detect. To get more complete detection coverage, you may want to scan your computer with additional antivirus programs while leaving a single antivirus program – such as Microsoft Security Essentials (known as Windows Defender in Windows 8) — running in the background.
The additional antivirus programs you’ll use won’t stay running in the background. They’ll scan your computer once and give you a second opinion. You can load up the additional programs and scan your computer once a week with them. While running the manual scanner, you should consider disabling real-time protection in your primary antivirus program – if only to speed things up.
When you select an additional antivirus program, look for one that doesn’t stay running in the background – this feature is referred to by many names, such as real-time protection, on-access scanning, background protection, or resident shield.
There are several options for second-opinion scanning, including:
When looking for a second-opinion antivirus, try to avoid the more lightweight options. Some products, such as Bitdefender QuickScan, may do a very quick scan that won’t necessarily find some malware. Bitdefender QuickScan and other products like it don’t remove malware they find, either – they exist to point you towards the company’s paid product.
If you have a suspicious file – perhaps you just downloaded it and are a bit worried or your antivirus says it’s malicious but the creator insists that your antivirus is offering up a false positive and the file is actually completely safe – you may want to scan that specific file with a variety of different antivirus programs.
Unfortunately, this can be difficult when you don’t have twenty different antivirus engines on your computer. Even if you did, updating each with the latest virus definitions would be way too much work.
When you need to scan a suspicious file in multiple antivirus programs, use the VirusTotal website – now owned by Google. You can upload files up to 32MB in size or even point VirusTotal at a URL online where it can download a file to analyze. The file will be scanned by 46 different antivirus programs on VirusTotal’s servers and you’ll see a report.
As with all antivirus programs, there’s no guarantee that the results are perfect. A file could be considered clean by every antivirus program but still be malicious. It’s also theoretically possible (although very unlikely) that a false positive could be marked as such by many different antiviruses. However, in practice, VirusTotal will tell you what a wide variety of antivirus programs think of a file, which can help you make a more informed decision about it.