To check for viruses on Windows 11, open Windows Security (search for it in Start), click Virus & threat protection, and click Quick scan. For a thorough check, click Scan options, choose Full scan and click Scan now. If you suspect malware that hides while Windows runs, choose Microsoft Defender Offline scan, which restarts the PC and scans before Windows loads.
Quick Answer
Windows Security > Virus & threat protection > Scan options > Full scan > Scan now.
Steps to Scan for Viruses
- Open Start, type Windows Security and open it.
- Click Virus & threat protection.
- Click Check for updates under protection updates first.
- Click Scan options, choose Full scan, and click Scan now.
- Review any threats found and choose Remove or Quarantine.
Scan Types
| Scan | Time | Use when |
|---|---|---|
| Quick scan | Minutes | Routine checks |
| Full scan | Often an hour or more | You suspect an infection |
| Custom scan | Varies | Checking a download or USB drive |
| Offline scan | About 15 minutes, with a restart | Malware that resists removal |
Signs You Might Have Malware
- Pop-ups when no browser is open, or new toolbars and extensions.
- Browser home page or search engine changed without you.
- Unknown programs in Task Manager > Startup.
- Security settings turned off that you didn’t change.
Troubleshooting
- Windows Security won’t open or is turned off: Another antivirus may be managing protection, or malware may have disabled it. Run the offline scan.
- Pop-ups continue: See stopping pop-ups.
- More malware help: See scanning for malware on Windows 11. On Windows 10, see checking for viruses on Windows 10.
Frequently Asked Questions
Is Windows Security enough?
For most home users, yes, when kept updated and combined with safe browsing habits.
Can I get a second opinion?
Yes. Microsoft’s Safety Scanner or a reputable on-demand scanner can run alongside it.
Should I scan USB drives?
Yes. Right-click the drive and choose Show more options > Scan with Microsoft Defender.
Summary
- Open Windows Security.
- Update protection.
- Run a Full scan.
- Use the offline scan for stubborn threats.
Kermit Matthews is a freelance writer based in Philadelphia, Pennsylvania with more than a decade of experience writing technology guides. He has a Bachelor’s and Master’s degree in Computer Science and has spent much of his professional career in IT management.
He specializes in writing content about iPhones, Android devices, Microsoft Office, and many other popular applications and devices.