Using More Than One Antivirus Software – Good or Bad?


Like the gunslingers of the Old West, you might believe two Colt 45's across your belt, a Derringer hidden in your waistcoat, and a Winchester cradled in your arms will keep you from major harm – meaning you just can't have too much protection. However, whilst this may have been an effective approach way back 'when the West was won', it rarely pays dividends with present-day computer security. In most circumstances, installing two or more antivirus software packages is counter-productive, as discussed below.


In essence, an antivirus program monitors your system looking for suspicious programs which may, for example, be logging and reporting back information about your system and its contents. Consequently, when antivirus software encounters another antivirus package installed on the same system and engaged in similar routines, it is likely to interpret such activity as a threat and attempt to disable and destroy its rival.

Similarly, when encountering a genuine virus, the best antivirus software packages hastily take action to neutralize and quarantine the malicious viral intruder. However, when another antivirus package is also present, it too may well detect the same threat and will react by sending, and endlessly re-sending, alerts detailing what it sees as a system-security issue, even though the original antivirus software has the matter in hand.

Legitimate security routines undertaken by a single antivirus package are designed to run in the background and consume only a small amount of system resources. On the other hand, competing antivirus packages fight for system resources and the resultant arm-wrestle can paralyze your system, with the conflict often affecting the accomplishment and outcome of even the simplest operations.

Secure Strategy

For the majority of domestic computer users, running two antivirus software packages running concurrently is both risky and hardly likely to offer benefits.

Computer systems generally operate one real-time antivirus software program in conjunction with a firewall. In this scenario the antivirus software monitors files which are accessed or downloaded, whilst the firewall defends the system against incoming threats from external network and/or internet sources – some firewalls can monitor outgoing traffic too. Occasionally, a 'security suite' will perform both functions in one package whilst still identifying and maintaining clear task-separation to avoid potential conflicts.

Additional protection

One possible exception to the rules regarding the deployment of multiple software packages is the use of individual programs designed to detect spyware and malware. These programs must not be run whilst normal security software is active, and should scan a system only when the user requests such action. Though all the best antivirus software programs continually monitor and update their routines to safeguard users against breaches of security, in a few cases, some packages will detect viruses others may miss.

Advanced configuration

Before considering additional protection beyond the firewall + antivirus package strategy, it is very important to understand that successful operation of additional software primarily depends on accurate configuration, not only of new, but also of existing software.

One key issue to bear in mind is the concept of 'active protection' in the sense of 'always on and running in the background'. You should never run two active protection security programs with the same functionality at the same time. In addition, installing extra security programs for occasional, targeted security scans and similar operations will require your existing active-protection software to be temporarily disabled during the process. And, by the same token, running security checks via extra software will require active-protection software to be similarly disabled during each procedure to avoid conflicts.

Thus, for all but advanced users who understand the implications of running multiple security packages, it is best practice to stick to one firewall and one antivirus software package and let them do their jobs.


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