Think you've never been the victim of identity theft? Ask yourself this question: How would you know?

One of the challenges of identity theft is that it can take a long time to recognize that you're a victim. If someone breaks into your car, that shattered passenger-side window is a giveaway. If someone robs your home, you'll know as soon as you see you realize your flat-screen TV, laptop computer, and jewelry are all missing.

But if someone steals your identity? You might not realize the damage until months later, when you notice a string of suspicious charges on your credit card statement or a sudden dip in your bank account's balance.

Fortunately, there are clues that someone has stolen your identity. It’s important to take note of them: The faster you discover this crime the sooner you can cancel your credit cards, alert your bank, and scour your credit reports for loans and credit card accounts opened in your name by a scammer.

Here, then, are 10 signs that a criminal might be using your identity to make purchases or take out loans and open credit card accounts in your name.

1. New loans or credit card accounts taken out in your name

Has a bill arrived from a lender saying that you owe this month’s payment on a personal loan you don’t remember taking out? Maybe you receive a bill from a credit card you know you never applied for or used. These are sure signs that someone has taken out loans or applied for a credit card using your name and personal information. That criminal is now using that loan or credit card to go on a spending spree. If you notice these strange bills, immediately call the credit card provider or lender behind them and explain that you’ve never taken out these financial products.

2. Lenders reject your applications for loans or credit cards

Surprised that a lender or credit card provider rejected your application for a new loan or credit card, especially since you’ve never had problems getting accepted in the past? This could be a sign of identity theft, too. A scammer might have stolen your identity and used it to apply for several credit cards, run up their balances, and then never paid. Seeing this activity, lenders might now think you’re the one who was financially reckless, causing them to reject your credit or loan application.

3. Collection agencies keep calling

No one wants to hear from collection agencies. But what if one calls you claiming that you owe thousands of dollars on an overdue credit card or personal loan that you know you’ve never taken out? That, again, is a sign that someone has used your personal and financial information to take out credit cards and loans in your name. That same someone, of course, then never made any payments on these fraudulent accounts, causing the providers of these accounts to turn to a collection agency to collect what they’re owed.

4. Your mailbox is awfully quiet

Finding your mailbox empty these days? Scammers might be snatching your physical mail as a way to find out important personal and financial information about you. They may then use this information to steal your identity and take out loans and credit card accounts in your name.

5. You’ve reached your healthcare limits unexpectedly

You might not have visited the doctor much this year. You haven't had any hospital stays and you haven't signed up for physical therapy. Yet when you do visit your doctor you receive a notice from your healthcare provider that you've reached the limit of your yearly benefits. Even worse, your provider doesn't want to pay for that recent visit.

What happened? A scammer might have stolen your healthcare information and might be using it to obtain medical treatment. Healthcare costs are high. Just a few major surgeries or treatments could exhaust your coverage.

If your healthcare benefits are suddenly cut off, don't be surprised if someone's stolen your identity.

6. Your credit score drops unexpectedly

Do you pride yourself on having a strong credit score? You should. In many countries, a high credit score gives you the best chance to qualify for loans and credit cards at the best rates. But what if your credit score suddenly drops? That could be the sign that a criminal has stolen your identity. Maybe this scammer opened a credit card account in your name, ran up major charges and then never paid for any of them. That could hurt your credit score. Or maybe this thief took out multiple loans using your personal information and never made the monthly payments on any of them. That, too, could cause your credit score to plummet.

7. Credit card charges show up for items you’ve never purchased

What if you see a big purchase from a store at which you’ve never shopped on your credit card statement? Or maybe you’re surprised by a series of charges from an overseas location you’ve never visited. Again, this is a sign that someone has stolen enough of your information to access your credit card account and hasn’t been hesitant to go on a shopping spree.

8. Unusual charges on your bank account statements

You should be checking your online bank account regularly, looking for withdrawals or purchases you’ve never made. If you find some, that could be a sign that someone is using your personal and financial information to make purchases from your account. This thief could be using your debit card account to make online purchases, siphoning the money from your bank account to pay for them.

9. Unexplained medical bills

It’s not unusual for criminals to use your personal information to pay for medical services, everything from prescription medications to major surgeries. You might be surprised, then, to find a hefty medical bill in your mailbox one day. If the bill is from a doctor or hospital that you don’t recognize, or for a procedure you’ve never had or a medication you don’t take, that’s a clear sign that someone is using your identity to cover their medical expenses.

10. A text from your credit card provider questioning a large purchase

Many credit card providers text their customers when they notice a large or unusual charge on their accounts. Maybe your provider notices that someone has used your card to pay for a series of meals in a tourist destination hundreds of miles away. Or maybe your provider notices that someone has used your card to charge a home-entertainment system costing big money. Often, your provider will send you a text asking you to confirm this purchase before they allow it to clear. If you receive one of these texts and you know you didn’t use your card for the purchase, be careful: Someone might be using your credit card information for a shopping spree.