Do I have a virus? How to check and what to do next

How do I know if I have a virus?

A virus does not always announce itself with a digital alarm bell. Malware can infect computers, phones, and tablets quietly, leaving you to connect the dots from small changes that seem unusual. If you are wondering, “Do I have a virus?”, the first step is to look for patterns rather than one random glitch.

Watch for sudden slowdowns, overheating, crashes, unusual pop-ups, browser redirects, unfamiliar apps, or battery drain that does not match your normal use. None of these signs on its own proves your device is infected, but a pattern of strange behavior is worth taking seriously. The earlier you check, the easier it is to stop malware from doing more damage.

Signs you have a virus on your computer

Computer viruses can make their presence known in small, annoying ways before they cause obvious damage. The clearest warning signs usually show up in everyday use:

• Slow performance, freezes, or crashes. Your computer suddenly takes longer to start, open programs, or complete basic tasks.
• Excessive pop-ups or browser redirects. You keep seeing ads, suspicious warnings, or pages opening without your action, including fake virus warning pop-ups.
• Unfamiliar programs or browser changes. New apps, toolbars, extensions, or a changed homepage appear without your permission.
• Disabled security tools. Your antivirus software turns off, will not open, or your security settings become inaccessible.
• Unexplained drive activity or storage loss. Your device runs in the background for no clear reason, or storage disappears unexpectedly.
• Programs opening or closing on their own. Apps launch, crash, or shut down without you clicking anything.
• Messages sent without your knowledge. Emails or social media messages go out from your accounts even though you did not send them.

If several of these symptoms appear together, check your device for malware.

Do I have a trojan virus on my computer?

You may have a trojan on your computer if the warning signs started after you downloaded a suspicious file, opened an unknown attachment, installed cracked software, or clicked a fake update.

That said, a trojan is malware that disguises itself as a legitimate program, so symptoms alone usually cannot confirm it. Run a full antivirus scan and review unknown programs or startup items. If you want to understand why trojans are harder to spot than ordinary suspicious files, read more about what a trojan is and how it works.

Signs you have a virus on your phone

Mobile malware can hide behind a legitimate-looking app or appear to bean ordinary battery problem at first, but repeated strange behavior can point to a more serious issue.

Android phones can face more risk because they usually allow app installs from more sources, but iPhones are not immune — especially if they are jailbroken or running outdated software. A jailbroken iPhone has Apple’s built-in restrictions removed, making it easier to install unapproved apps and weakening some of the protections that normally limit what apps can access.

Because mobile malware often shows up as unusual behavior rather than an obvious warning, watch for these signs:

• Unexplained data usage spikes. Your phone suddenly uses much more mobile data than usual, even when your habits have not changed.
• Rapid battery drain. The battery runs out much faster than normal because a suspicious app or process may be active in the background.
• Overheating when idle. Your phone gets hot even when you are not gaming, streaming, charging, or using processor-intensive apps.
• Unfamiliar apps. New apps appear on your phone, and you do not remember downloading or approving them.
• Frequent crashes or sluggish performance. Apps freeze, your phone slows down, or the system becomes unstable without a clear reason. These issues can also come from outdated software or aging hardware.
• Pop-up ads outside browsers. Ads, warnings, or redirects appear on your home screen, lock screen, or inside apps where they should not appear.

These signs do not automatically confirm a phone virus. Old batteries, buggy apps, low storage, or outdated software can cause similar issues. If these issues appear around the same time, check your phone more carefully — especially if you use an Android phone or a jailbroken iPhone.

How do I check if I have a virus on my phone or computer?

Once you spot several warning signs, check the areas malware usually affects: scans, apps, background activity, permissions, and browser settings.

How to check for a virus on your computer

If you are wondering, “Do I have a virus on my computer?”, start with a full system scan. Then check whether anything suspicious is running in the background or changing your browser settings.

• Run a full antivirus scan. Open your antivirus software and scan the whole system, not just recent downloads.
• Use Microsoft Defender on Windows. Go to “Windows security” > “Scan options” and choose “Quick scan,” “Full scan,” or “Offline scan.”
• Check background processes. On Windows, open the task manager. On Mac, open the activity monitor. Look for unfamiliar apps or processes using unusually high CPU, memory, disk, or network resources.
• Review browser settings. Remove unknown extensions, toolbars, or search engine changes, especially if redirects are the main issue.
• Run a second-opinion scan. If your main antivirus finds nothing, but the symptoms continue, try using a different trusted scanner to check for threats your first scan may have missed.

Browser issues may also need a more focused check. If the problem mainly appears in Chrome, a Chrome virus scan can help you find suspicious extensions, redirects, or browser hijackers — malicious software that takes control of your browser.

If you use macOS, it’s also worth understanding whether Macs can get viruses. The short answer is yes, though macOS threats often look different from classic Windows malware.

How to check for a virus on your phone

If you are asking yourself, “How do I check if I have a virus on my phone?”, start with your apps, settings, and recent activity. Phone malware often comes from suspicious downloads, unofficial app stores, fake updates, or apps with more permissions than they need.

• Review installed apps. Delete anything unfamiliar, suspicious, or installed from outside trusted sources.
• Check app permissions. Look for apps with unnecessary access to your SMS, contacts, location, microphone, camera, or accessibility settings.
• Check battery and data usage. Look for apps using unusual power or mobile data in the background.
• Look for suspicious browser activity. Check for pop-ups, redirects, strange notifications, or changed browser settings.
• Use built-in security tools where available. Run a device or app scan if your phone supports it.

On an Android device, you can start with Google Play Protect by opening the Play Store, going to Play Protect, and scanning your apps. You can also use a reputable mobile security app from the official Play Store, but avoid random “cleaner” apps or urgent pop-ups claiming your phone is infected.

On an iPhone, the check is different because iOS does not support traditional full-system antivirus scanning like computers do. Apps are sandboxed, meaning each app is kept in its own restricted space and cannot freely access other apps or core system files. To check your iPhone for viruses, focus on unfamiliar apps, unusual battery or data usage, suspicious profiles, strange pop-ups, and whether the device is jailbroken.

What to do if you have a virus on your phone or computer

If several warning signs appear together, act quickly without panic-clicking through alerts or installing random “cleaner” tools. Start by limiting the damage, removing suspicious software, updating the device, and protecting any accounts you used on it.

What to do if you have a virus on your computer

If you think your computer has a virus, start by limiting what the malware can do. Disconnect from the internet first, then scan the device and clean up any suspicious browser or system changes. Follow these steps:

• Disconnect from the internet. Turn off Wi-Fi or unplug the Ethernet cable to stop malware from spreading, sending data out, or getting new commands from whoever is controlling it.
• Boot into safe mode. Safe mode starts your computer with only essential files and services, which can make malware easier to remove.
• Run a full antivirus scan. Scan the whole system, then quarantine or delete anything your antivirus detects.
• Delete temporary files. Clear temp folders to remove leftover files and help the scan run more efficiently.
• Check your browser. Remove unfamiliar extensions, toolbars, or add-ons, especially if you noticed redirects or pop-ups.
• Reset browser settings. Reset browser settings if your homepage, search engine, or new tab page keeps changing without permission.

If the same problem keeps coming back, a factory reset may be the safest last resort. Back up important files first, but avoid restoring suspicious downloads, unknown apps, or full old backups that may contain the same problem.

After the reset, install the latest operating system version and app updates before using the device normally again. Security updates fix known weaknesses that malware could use to get back in. If the symptoms keep coming back after a scan and browser cleanup, follow a more detailed guide on how to get rid of malware or a virus.

What to do if you have a virus on your phone

If you think your phone has a virus, start with suspicious apps and recent changes. Phone malware is often tied to unsafe downloads, fake updates, or apps installed outside official app stores.

• Delete suspicious apps. Remove unfamiliar apps, fake updates, cleaners, or anything installed from untrusted sources.
• Clear browser cache and data. This can help remove redirects, pop-ups, and suspicious site data.
• Restart in safe mode on Android. Safe mode disables third-party apps, helping you identify which app is causing problems.
• Update your phone. Install the latest Android or iOS update to fix known vulnerabilities.
• Review iPhone settings. Check installed apps, battery and data usage, suspicious profiles, and whether the device is jailbroken.
• Change your passwords. Use a clean device to update passwords for accounts you accessed on the affected phone.

If the problem continues, back up important data and perform a factory reset as a last resort.

How to prevent viruses and malware

Removing malware, spyware, trojans, or viruses is usually harder than avoiding them. These habits can lower your risk:

• Keep your OS and apps updated. Updates fix security gaps that malware could use to get into your device.
• Only download apps from official stores. Stick to Google Play or the App Store. Unverified sources are one of the most common infection routes, especially on Android.
• Don’t click suspicious links or open unknown attachments. If a message sounds urgent or arrives unexpectedly, go directly to the website instead of following a link.
• Use a strong, unique password and enable two-factor authentication. A different password for every account, plus 2FA, limits the damage if one gets compromised. Here’s how to create a strong password.
• Protect your connection on public Wi-Fi. A VPN will not stop every virus, but it encrypts your connection and helps protect your data from other people on the same network.

Most present-day online threats — phishing, scams, fraudulent pages, identity theft attempts — do not arrive as infected files. That’s where a next-gen antivirus comes in. It differs from a traditional, file-scanning one: It is privacy-focused and proactive, helping block unsafe websites and scam pages before they load and malicious downloads before they can cause damage.

NordVPN’s next-gen antivirus is available in the NordVPN app on Windows and macOS with a Plus or higher plan. Together with a VPN, it gives you an all-in-one* digital security solution that helps block phishing, scams, malware, and unsafe websites as well as encrypts your connection.

*”All-in-one" refers to the VPN, scam protection, phishing protection, tracker and ad blocking, and other features available within the NordVPN app, depending on your device and the plan you choose.