Medical identity theft has affected millions of adults in the U.S., and it can wreak havoc on your finances and health.

Medical identity theft happens when someone steals your personally identifiable information and can use it to get medical services and prescription drugs in your name. This could leave you footing the bill and potentially getting a stranger's health information mixed into yours.

You can help protect against medical identity theft—or if it's already happened, stop it before it gets worse.

Here are three tips on how to help protect against medical identity theft.

1. Get a copy of your medical records

Under federal law, you have the right to know what’s in your medical records, except in certain circumstances. Ask your doctors for a copy of your medical files, so you have all your documentation in case you need to report identity theft.

If a thief has already stolen your information, doctors may hesitate before handing over your records—to them, it may violate the identity thief’s privacy rights. If this occurs, check out the Federal Trade Commission's explanation on how to file a correction of your medical records.

Every time you visit a doctor or have a medical procedure, consider recording the date and time, name of the doctor, what you discussed, and the outcome. Keep these records in a safe place.

2. Check your explanation of benefits and credit report

You'll get explanation-of-benefits documents every time you visit a doctor and pay using insurance. EOB documents show the services you received and what the insurer covered.

When you get one of these summaries, check it against your own records. If the date of service, name of provider and service provided don't match the care you received, this may be a problem. Another red flag? Opening an EOB for a service you never received.

If you spot a mistake or something suspicious, call your health insurer and report the problem.

Here’s another document you should check regularly: your credit report. If you notice accounts you didn't open or collections for debt you don't owe, alert the company, the FTC, and the police.

3. Protect your medical information

A rule of thumb: Never share your health insurance information, Social Security number or any other personally identifiable information with anyone.

Of course, there are exceptions. You'll need to give some of this information to your medical providers. But first, ask why they need it, whether they will share it, and how they will keep it safe.

Don’t share medical or insurance information on the phone or by email, unless you've initiated the communication and you know who you're dealing with. Before you share information online, check for a URL that begins “https:” (the "s" is for "secure") or a lock icon on the browser’s status bar.

Be careful when discarding your information, too. Before you toss out anything with sensitive information—like health insurance forms, prescription and physician statements, and the labels from prescription bottles—shred them.