How do I tell if my computer has a virus?
The real symptoms, the fake warnings that are themselves the scam, and how to check properly.
- Difficulty
- beginner
- Time
- 45 min
- Read
- 2 min
- Safety
- warning
Short answer
Run a full scan with the built-in security software, which is genuinely good. And a pop-up telling you that you have a virus and to call a number is the scam itself — never call it.
Actual infections are less common than they were and fake warnings are far more common. Knowing the difference matters, because the most damaging outcome is usually calling the number in the pop-up rather than the original problem.
Safety
Step by step
- Recognise the fake warning first.A pop-up or full-screen page saying you are infected and giving a phone number is always a scam. Real security software never asks you to phone anyone. Close the browser and do not call.
- Close a locked browser safely.Force-quit the browser rather than clicking anything in the page. Task Manager on Windows, Force Quit on Mac. Then reopen without restoring the previous session.
- Know the real symptoms.Sudden severe slowness, programs you did not install, the browser homepage or search engine changed, unexpected pop-ups outside the browser, the fan running constantly, contacts receiving messages you did not send.
- Run a full scan with the built-in software.Windows Security on Windows is genuinely effective and needs no third-party addition. Run a full scan rather than a quick one, and let it finish.
- Run one reputable second-opinion scanner.A single well-known on-demand scanner as a cross-check. Do not install several — multiple resident security products conflict and slow the machine badly.
- Check what starts automatically and what is installed.Browser extensions especially. Unwanted extensions are the most common real problem and are usually removed by hand rather than by a scanner.
- Change passwords from a different device.If you believe something got in, assume passwords were captured. Change them from a device you trust, starting with email and banking, and turn on two-factor.
- Reinstall if it persists.A clean reinstall from backed-up personal files is the reliable answer for a stubborn infection, and is often quicker than repeated attempts to clean.
Tips
- Most modern "virus" problems are unwanted browser extensions and adware rather than viruses. Check extensions before assuming the worst.
- Free antivirus that arrived bundled with something is often worse than the built-in protection. One security product, not three.
- Keep the operating system and browser updated. That prevents far more than any scanner detects.
Questions people ask
Is a pop-up saying I have a virus real?
No. Real security software never displays a phone number to call. It is a scam designed to get remote access to your computer — close the browser and never call.
Do I need to buy antivirus software?
Generally not. The built-in protection on modern systems is effective. Keeping everything updated matters more than which product you use.