The fastest way to check your Mac for viruses
Start by running a scan with Malwarebytes for Mac, which finds threats that Apple's built-in protection sometimes misses. Download it from malwarebytes.com, install it, open the app, and click the "Scan" button. The scan takes 5 to 15 minutes depending on how much is on your drive. If it finds anything, Malwarebytes will show you the name and location — you can remove it from the same screen.
If you want to check what Apple's own protection has already caught, open System Settings, go to Privacy & Security, scroll down to Security, and look at the section that says "Virus and threat protection." This shows you whether macOS has blocked anything recently. Apple's Gatekeeper and XProtect run automatically in the background, so you may already be protected without knowing it.
For a second opinion, Sophos Home (free version) is another solid choice. It scans differently than Malwarebytes, so running both gives you more confidence. Download from sophos.com, install, and run a full scan the same way.
Key Takeaways
- Malwarebytes for Mac is the fastest way to scan for viruses and malware that Apple's built-in tools might miss.
- Check System Settings under Privacy & Security to see whether macOS has already blocked threats in the background.
- Running two different scanning tools (like Malwarebytes and Sophos Home) catches more threats than one alone.
- If a scan finds something, the app will show you the name and location and let you remove it immediately.
- Restart your Mac in Safe Mode if a virus is behaving strangely or won't let you run scans normally.
When your Mac is running slowly or acting strange
Slow performance, unexpected crashes, or apps that won't open can point to a virus, but they also happen for other reasons. Before you assume malware, restart your Mac — this clears temporary files and stops background processes that might be slowing things down. Hold the power button for 10 seconds, wait for the Mac to shut down, then press the power button again to turn it back on.
If slowness continues after a restart, open Activity Monitor (search for it in Spotlight by pressing Command+Space, typing "Activity Monitor," and pressing Enter). Click the CPU tab and look at the "% CPU" column. If one app is using more than 50% of your processor when you're not actively using it, that's a sign something is wrong. Note the app name and search for it online — you may find it's a known malware variant or a legitimate app with a bug.
Unexpected pop-ups, especially ones that ask you to call a number or download something, are almost always malware. Do not click anything in the pop-up. Force-quit the browser by pressing Command+Q or by opening Activity Monitor, selecting the browser, and clicking the X button. Then run a Malwarebytes scan.
How to scan in Safe Mode if normal scanning won't work
If a virus is preventing you from running scans or opening apps, restart your Mac in Safe Mode. This loads only the essential files macOS needs to run, which stops most malware from launching. Shut down your Mac completely, then turn it back on and immediately hold the Shift key. Keep holding Shift until you see "Loading startup items" on the screen, then release. Your Mac will take longer to start up — this is normal.
Once you're in Safe Mode, you'll notice the login screen says "Safe Boot" in the upper right corner. Log in with your password. Now download Malwarebytes (if you haven't already) and run a full scan. Safe Mode gives the scan a better chance of finding and removing threats because the malware isn't actively defending itself.
After the scan finishes and you've removed any threats, restart your Mac normally by going to the Apple menu, clicking Shut Down, and then turning it back on without holding Shift. Your Mac will boot normally this time.
What to do if you think you've been hacked
If you suspect someone has accessed your accounts — for example, you see login attempts from places you've never been or your passwords have changed — change your passwords immediately from a different device if possible. Use a strong password with uppercase letters, numbers, and symbols. For accounts that matter most (email, banking, social media), turn on two-factor authentication if the service offers it.
Check your email forwarding rules to make sure no one has set up a rule to automatically send your mail somewhere else. In Gmail, click the Settings gear, go to Forwarding and POP/IMAP, and look at the Forwarding address field. In Outlook, go to Settings, Mail, Forwarding, and check the same thing. If you see a forwarding address you didn't create, delete it.
After you've changed passwords and checked forwarding, run a full Malwarebytes scan. Even if the scan finds nothing, the malware may have already left your Mac — the important thing is to secure your accounts so the attacker can't get back in using stolen passwords.
Preventing viruses before they get on your Mac
The best protection is not clicking links or downloading files from sources you don't trust. Malware usually arrives through email attachments, fake download buttons on websites, or apps from outside the App Store. If an email asks you to click a link and enter your password, it's almost certainly fake — banks and services never ask for passwords by email.
Keep macOS updated. Go to System Settings, click General, then Software Update, and install any updates that appear. These updates patch security holes that malware exploits. Turn on automatic updates so you don't have to remember to check manually.
Download apps only from the App Store or directly from the company's official website. If you download from a third-party site like MacUpdate or SourceForge, you're taking a bigger risk. When you download an app from outside the App Store, macOS will ask you to confirm that you want to open it — read the warning and make sure you recognize the company name before clicking Open.
Understanding what Apple's built-in protection does
Gatekeeper checks every app you download to make sure it comes from a trusted source and hasn't been tampered with. When you open an app for the first time, Gatekeeper scans it. If it finds a problem, macOS will refuse to open it and show you a warning. This happens silently in the background most of the time.
XProtect is Apple's antivirus engine. It runs automatically and compares files on your Mac against a database of known malware. When you download a file, XProtect scans it. If it matches a known threat, macOS will quarantine the file and show you a notification. XProtect updates its malware definitions regularly, though not as often as third-party tools like Malwarebytes.
These tools are good, but they're not perfect. They catch common threats and known malware, but new viruses and zero-day exploits (attacks that use previously unknown security holes) can slip past. This is why running a third-party scan with Malwarebytes once a month is a smart extra step.
Removing malware that won't go away
If Malwarebytes finds something but can't remove it, or if the threat keeps coming back after you remove it, the malware may have infected system files. Restart in Safe Mode again and run another Malwarebytes scan. Sometimes a second scan catches what the first one missed because the malware behaves differently when it can't load all its components.
If the problem persists, you may need to erase your Mac and reinstall macOS. This is a last resort, but it guarantees the malware is gone. Before you do this, back up your important files to an external drive or iCloud. Then go to System Settings, General, Transfer or Reset, and follow the steps to erase your Mac. You'll need your Apple ID password and will have to reinstall macOS from scratch, which takes an hour or two.
If you're not comfortable doing this yourself, take your Mac to an Apple Store or a local repair shop. Tell them you suspect malware and want the drive erased and macOS reinstalled. They can do this quickly and safely.
Frequently Asked Questions
Can Macs get viruses?
Yes. While macOS is more secure than Windows in some ways, Macs absolutely get viruses and malware. The belief that Macs are immune is outdated. Malware designed for Mac exists and spreads the same way it does on any computer — through downloads, email attachments, and malicious websites.
Do I need antivirus software if I have a Mac?
Apple's built-in protection (Gatekeeper and XProtect) catches many threats, but it misses some. Running Malwarebytes or Sophos Home once a month gives you extra protection without slowing your Mac down. You don't need to run it constantly — a monthly scan is enough for most people.
What does it mean if Malwarebytes finds something?
It means a file on your Mac matches a known malware signature. Click Remove and Malwarebytes will delete it. If the same threat keeps coming back, it may be hiding in a location Malwarebytes can't access, or you may have downloaded it again from the same source. Stop downloading from that source and run a scan in Safe Mode.
Is it safe to download Malwarebytes?
Yes. Malwarebytes is a legitimate company and the free version is safe. Download only from malwarebytes.com, not from other sites. If you search for "Malwarebytes" and see results from other download sites, ignore them and go directly to the official website.
How often should I scan my Mac for viruses?
Once a month is enough for most people. If you download files frequently from untrusted sources, download torrents, or visit risky websites, scan every two weeks. If you mostly use the App Store and official websites, once a month is fine.