Use Windows Defender Periodic Scanning with a Third-Party Antivirus

Use Windows Defender Periodic Scanning with a Third-Party Antivirus​

Difficulty: Beginner | Time Required: 10 minutes
Windows includes Microsoft Defender Antivirus, but many users prefer to run a third-party antivirus such as Norton, Bitdefender, Malwarebytes Premium, ESET, Avast, AVG, McAfee, or another security suite. When a third-party antivirus is installed and working correctly, Microsoft Defender Antivirus usually turns itself off automatically so the two products do not compete for real-time protection.
However, Windows 10 and Windows 11 include an optional feature called Periodic scanning, also known as limited periodic scanning. This lets Microsoft Defender Antivirus occasionally scan your PC for threats while your third-party antivirus remains your main protection.
Think of it as a “second opinion” scanner. It is not a replacement for your primary antivirus, but it can provide an extra layer of malware detection with very little setup.

Prerequisites​

Before you begin, make sure you have the following:

• A Windows 10 or Windows 11 PC
• A third-party antivirus installed and active
• Access to the Windows Security app
• A standard user account is usually enough, but administrator permission may be required for some security changes

Note: Periodic scanning is intended for personal Windows 10 and Windows 11 devices using a non-Microsoft antivirus product. It is not designed as a managed enterprise security feature.

What Periodic Scanning Does​

When enabled, Microsoft Defender Antivirus performs occasional scans in the background. If it finds a threat, Windows Security can notify you so you can review and take action.
Periodic scanning does not make Microsoft Defender your primary antivirus. Your third-party antivirus continues to handle real-time protection, active monitoring, and most day-to-day threat blocking.
This feature is useful if you want:

• A second layer of detection
• Occasional checks from Microsoft Defender
• Extra peace of mind without uninstalling your current antivirus
• A simple built-in option that does not require another security tool

Step-by-Step: Enable Periodic Scanning​

1. Open Windows Security​

1. Click Start.
2. Type Windows Security.
3. Select Windows Security from the search results.

You can also open it from:

1. Settings
2. Privacy & security on Windows 11, or Update & Security on Windows 10
3. Windows Security
4. Open Windows Security

2. Go to Virus & Threat Protection​

1. In the Windows Security window, select Virus & threat protection.
2. Look near the top of the page.

If your third-party antivirus is installed correctly, Windows Security should show that your current antivirus provider is managing virus and threat protection.
For example, you may see the name of your antivirus product listed instead of Microsoft Defender Antivirus being shown as the active provider.

3. Open Microsoft Defender Antivirus Options​

1. On the Virus & threat protection page, look for Microsoft Defender Antivirus options.
2. Click or expand that section.

This option usually appears only when another antivirus product is installed and active.

Tip: If you do not see Microsoft Defender Antivirus options, see the troubleshooting section below.

4. Turn On Periodic Scanning​

1. Under Microsoft Defender Antivirus options, find Periodic scanning.
2. Move the toggle switch to On.
3. If Windows asks for confirmation through User Account Control, choose Yes.

That’s it. Microsoft Defender will now perform limited periodic scans while your third-party antivirus remains your main antivirus.

5. Optional: Run a Manual Microsoft Defender Scan​

After enabling periodic scanning, you may want to run a quick scan manually.

1. Stay in Windows Security.
2. Go to Virus & threat protection.
3. Under the Microsoft Defender section, choose Quick scan if available.

A quick scan checks common locations where malware is often found. It usually completes faster than a full scan.
If you want a deeper check:

1. Select Scan options.
2. Choose Full scan.
3. Select Scan now.

Note: A full scan can take a long time depending on the number of files, drive speed, and system performance.

How to Turn Periodic Scanning Off​

If you later decide you do not want Microsoft Defender performing occasional scans:

1. Open Windows Security.
2. Select Virus & threat protection.
3. Expand Microsoft Defender Antivirus options.
4. Turn Periodic scanning to Off.

Your third-party antivirus will continue to protect your system as before.

Tips for Best Results​

Keep Windows Updated​

Periodic scanning works best when Windows and Microsoft Defender security intelligence are up to date. Windows normally updates these automatically through Windows Update.
To check manually:

1. Open Settings.
2. Go to Windows Update.
3. Select Check for updates.

Keep Your Third-Party Antivirus Active​

Periodic scanning is only a supplement. Your third-party antivirus should remain installed, licensed, updated, and actively protecting your PC.
If your antivirus subscription expires or the program stops working, Windows may attempt to turn Microsoft Defender Antivirus back on as the main protection provider.

Do Not Run Multiple Real-Time Antivirus Products​

Using Periodic scanning is different from forcing two antivirus products to run full real-time protection at the same time. Multiple real-time antivirus engines can cause slowdowns, alerts, file access problems, or system instability.
Let your third-party antivirus remain the main real-time scanner, and use Microsoft Defender only for periodic checks.

Review Notifications Promptly​

If Windows Security notifies you that Microsoft Defender found something, do not ignore it.
Open Windows Security and review the recommended action. Depending on the detection, you may be able to quarantine, remove, or allow an item.
Only allow a detected item if you are completely sure it is safe.

Troubleshooting​

I Do Not See “Microsoft Defender Antivirus Options”​

This usually happens for one of these reasons:

1. No third-party antivirus is installed.
   If Microsoft Defender is already your main antivirus, periodic scanning is not needed because Defender is already active.
2. Your third-party antivirus is not registered correctly with Windows Security.
   Open your antivirus program and check that it is installed, activated, and up to date. Restarting the PC may also help.
3. Your antivirus is expired or disabled.
   If your third-party antivirus is not working correctly, Windows may enable Microsoft Defender as the primary antivirus instead.
4. Your device is managed by work or school.
   Organization-managed devices may hide or control security settings.
5. You are using an unsupported configuration.
   Periodic scanning is primarily meant for Windows 10 and Windows 11 client PCs, not managed enterprise deployments.

The Toggle Turns Off Again​

If the setting does not stay enabled:

1. Restart your PC.
2. Confirm your third-party antivirus is active.
3. Check for Windows updates.
4. Open Windows Security again and try enabling the setting.

If your PC is managed by an organization, policy settings may prevent you from changing this option.

My PC Feels Slower During Scans​

Antivirus scans can temporarily use CPU, disk, and memory resources. If you notice slowdowns:

• Run manual scans when you are not gaming or working
• Avoid starting a full scan on battery power
• Let Windows finish updates before scanning
• Use Quick scan for routine checks and Full scan only when needed

Conclusion​

Periodic scanning is a simple way to add Microsoft Defender’s limited scanning capability alongside your preferred third-party antivirus. It does not replace your existing antivirus, but it can provide an extra layer of detection and a little more confidence that your system is being checked from another angle.
For most home users, enabling it takes less than ten minutes and requires no advanced configuration.
Key Takeaways:

• Periodic scanning lets Microsoft Defender occasionally scan your PC while a third-party antivirus remains your main protection.
• It is available on Windows 10 and Windows 11 when another antivirus product is installed and working.
• It should be treated as a supplemental “second opinion,” not a replacement for full real-time antivirus protection.
• You can enable or disable it from Windows Security > Virus & threat protection > Microsoft Defender Antivirus options.
• Keep both Windows and your main antivirus updated for the best protection.

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This tutorial was generated to help WindowsForum.com users get the most out of their Windows experience.