How to get rid of a computer virus

Viruses are a persistent problem. A single mistake, such as clicking on a dodgy link or opening an unknown file, is all it takes for your computer to become infected.

Once a virus is on your system, it can slow your computer down, steal personal data or even lock your files entirely. In some cases, you might not even realise anything is wrong until the damage has already been done.

Fortunately, there are some simple steps to remove it – as our tech experts explain below - for both Windows PCs and Macs. Plus, we can recommend a top-notch antivirus to prevent it from happening again.

Discover the best antivirus for Windows based on our expert testing, to keep you safe from viruses, ransomware and phishing attacks. Got a Mac? See our best Mac antivirus 

What you need to know about viruses 

Viruses are a type of malware that infects computers and compromises the data, files and other information stored on them.

There are numerous ways viruses and other types of malware can be delivered to computers. Phishing – sending a hoax message designed to look genuine – is the most common method used today. These messages coerce you into clicking on a dodgy link or opening an infected attachment, often by claiming urgent action is needed. Once clicked or opened, a virus can be unleashed onto your computer and begin seeking out your personal and private data.

Artificial Intelligence (AI) is also making it easier for criminals to create malicious software and target more people. This means viruses are becoming an even greater threat, so it’s important to know how to protect yourself.

How do I know if my computer is infected?

There are a number of signs that your computer could be infected with a virus:

• Your device feels slower – programs take longer to open and everyday tasks feel unusually sluggish.
• You spot apps or browser extensions that you don’t remember downloading – these might have been installed without your knowledge.
• You receive numerous security alerts without running a system scan – frequent pop-ups can be a sign of malicious software activity. Often, these popups are designed to trick you into downloading more malware.
• Your stored files are locked – you may see a message demanding a ransom to regain access (never pay this, as it doesn’t guarantee your files will be restored – see our advice on how to deal with ransomware).
• Stored contacts receive random messages from you that you didn’t send – malware can use your account to spread itself to others.

How to remove a virus

If your device is experiencing any of the symptoms above, or you think you might have clicked on a dodgy link or opened a suspicious attachment, you should take immediate action. The longer you wait, the higher the chance your data could be compromised.

Remove a virus in Windows

1. Select the Start button, then open Settings (the cog icon).
2. Go to Apps (in Windows 10, select Apps > Apps & features; in Windows 11, select Apps > Installed apps).
3. Review the list of installed programs and look for anything you don’t recognise. If you find a suspicious app, select it and click Uninstall, then follow the on-screen instructions.
4. Once you’ve removed any unwanted apps, right-click your Recycle Bin and select Empty Recycle Bin.
5. Open File Explorer (the yellow folder icon), go to your Downloads folder, and delete any files you don’t recognise or didn’t intentionally download.

Next, we suggest installing a Which?-recommended Windows antivirus that can thoroughly scan your computer while disconnected from the internet. Avoid paid antivirus software, as this may expose your payment details to cyber criminals who may be monitoring or recording activity on your computer.

Once the antivirus is installed, disconnect your computer from the internet and reboot it in Safe Mode.

How to start Windows in Safe Mode

1. Select Start (either click the on-screen Start button or press the Windows key on your keyboard).
2. While holding down the Shift key, select Restart.
3. When your PC restarts, choose Troubleshoot > Advanced options > Startup Settings, then select Restart.
4. Press the key that corresponds to Enable Safe Mode (typically F4).

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Remove a virus on a Mac

1. Open Finder and check your Applications folder for any apps you don’t recognise or remember downloading. If there are any, delete them by selecting the app, then choosing File > Move to Bin.
2. Once done, empty the Bin (right-click the Bin icon in the Dock and select Empty Bin).
3. Follow the same steps in your Downloads folder.

Next, install a Which?-recommended free Mac antivirus that can thoroughly scan your computer while disconnected from the internet. Avoid paid antivirus as this could expose your payment details to cyber criminals who may be monitoring or recording activity on your computer.

Once the antivirus is installed, disconnect your computer from the internet and reboot it in Safe Mode.

How to start a Mac in Safe Mode 

Mac devices with Apple silicon (M1, M2, M3 or later – Macs released since November 2020):

1. Shut down your Mac completely, then press and hold the power button until Loading startup options appears.
2. Select your startup disk.
3. Press and hold the Shift key, then click Continue in Safe Mode.
4. Log in (you may be asked to log in twice) – you should now be in Safe Mode.

Older Mac devices (Intel, pre-November 2020):

1. Turn your Mac on or restart it, then immediately press and hold the Shift key.
2. Release the key when you see the login window.
3. Log in (you may be asked to log in twice).

What to do next: Windows and MacOS

Once rebooted into Safe Mode, run a full system scan with your antivirus to thoroughly remove any malware. When the scan is complete, you can restart your computer and reconnect to the internet.

We recommend updating all your passwords, especially those used while you believe your computer was infected, as they may have been compromised. Find out more about how to create secure passwords.

If you had any USB devices connected at the time, such as a USB stick or an external hard drive, it's best to scan these with your antivirus as well.

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Preventing future infection

Now your computer has been cleaned of any hidden viruses, it’s worth taking some time to shore up your cyber defences so this doesn’t happen again.

Our expert tests have shown that the best antivirus – whether paid or free – is highly effective at tackling threats and, crucially, flagging dodgy links and files.

Our expert lab tests have revealed the best antivirus. Got a Mac? See our best Mac antivirus