Aside from sluggish performance, one of the most commonly cited symptoms of an Android virus is that the web browser is redirecting to a porn site or you are experiencing dodgy pop-ups.

In such instances the best thing to do is clear your browser cache, either within the browser's own settings menu or by going to Apps & Notifications > Chrome > Storage > Clear Cache.

This is much less drastic than performing a system reset, which is the other surefire way to get rid of an Android virus, and possible via the Settings > System > Reset Options > Erase All Data menu.

But what if there are other things going on in the background that you don't know about?

Truth be told, Android viruses are incredibly rare. A misbehaving device is not usually caused by malware, but rather the ever-growing build-up of junk files, which will eventually cause the whole system to slow down (something a factory reset can also help).

But Android viruses do exist, and it is possible that your phone or tablet is suffering from a malicious software infection, usually brought about by the installation of a dodgy app from outside the confines of the Google Play store - but the Play Store is not always a safe haven.

In September 2019 it was confirmed that the Joker malware had been downloaded from Google Play more than half a million times. The virus was found in 24 apps, all of which have now been removed, where it cons users into signing up to premium subscription services without their knowledge.

With this in mind, Android antivirus apps such as Bitdefender Mobile Security are not necessary, but they can promote peace of mind by keeping tabs on your activity at times, especially when you're relaxing and have let down your guard. There are other options, too, and we've rounded up some of our favourites.

Such apps might be able to pinpoint and remove an infection for you, but if you know when all the trouble began you can manually remove the malicious app. You'll need to enter Safe mode first, which stops any third-party apps from running. If you don't have an option to access Safe mode in the Power options menu, try holding volume-down as you reboot the phone. You'll know it's worked if you see Safe mode in the bottom left corner of the screen.

Open Settings and select the Apps & Notifications menu, then scroll down the list and be on the lookout for any suspicious apps that could be behind all the drama - anything you don't remember downloading or that doesn't sound like a genuine Android service. Click the app's name to open its dedicated App Info page.

If this is not a preinstalled app you should see an Uninstall button at the top of this page. Press this if you can. If it's greyed out then it's likely the app has given itself administrator rights, which you can remove in Settings > Security & Location > Device Admin Apps. 

With the virus now off your Android phone or tablet, all you need to is restart the device to take it out of Safe mode.

Supposing you've done all the above and your device is still slow, consider that it may be a case of old age or a new software update that doesn't play nicely slowing things down. Check out our guide on how to speed up Android. Also read on below for how to avoid becoming a victim to Android malware once again.

Avoid future Android viruses and malware

• Don't install apps from outside Google Play unless you know what you're doing: This functionality should be disabled by default, but do check. In recent versions of Android the ability to install apps from unknown locations has changed from a system-wide permission to an app-specific permission. It's now found in Apps & Notifications > Advanced > Special App Access > Install unknown apps. If you do install an app outside Google Play, such as from another app store or an APK file that came as an attachment on an email or other message, be absolutely certain that it is above board and comes from a legitimate source

• Avoid cloned apps: 99 percent of the time you will be safe downloading apps from Google Play, but malicious code has been found within apps there. Avoid downloading what appear to be cloned apps from unknown developers, or apps that simply don't do what they say they do

• Check app permissions: No matter from where you are installing an app, check its required permissions before hitting Install. Never allow an app device admin permission, which prevents it being deleted. And does a video player really need to see your contacts? You can also check reviews online and browse the developer's website to see whether it's a genuine operation or cowboy business

• Keep Android up to date: The latest version of the Android operating system won't necessarily be available for your phone or tablet, but you should check that it is as up to date as it can be. Next time you upgrade, consider a brand that is known for its timely operating system updates. Check out our guide on how to update Android for further advice

• Install an antivirus app: You don't need to install antivirus on Android, but it can give you peace of mind if you're concerned about viruses, and the apps often have other useful functionality too. Be warned that Android antivirus is known to occasionally report false-positives, but if you know an app is okay you know an app is okay. Our favourite antivirus option for Android is Bitdefender, but there's also plenty of other options for mobile security software.