Dear Savvy Senior: I’m currently enrolled in original Medicare but have been thinking about switching to a Medicare Advantage plan during the open enrollment period. Many of the Medicare Advantage ads I’ve seen offer lots of extra benefits beyond what traditional Medicare offers and no monthly premiums. What are your thoughts? — Considering a Switch

Dear Considering: Be very leery of the Medicare Advantage ads on TV, radio, social media and in mailed promotional material. While many of these ads might tout free vision, hearing, dental and other benefits with zero monthly premiums, they aren’t always what they claim to be.

Medicare Advantage, also known as Medicare Part C, comprises government- approved health plans sold by private insurance companies that you can choose in place of original Medicare. The vast majority of Advantage plans are managed-care policies such as HMOs or preferred-provider organizations that require you to get your care within a network of doctors in a geographic area. You can sign up for one of them during open-enrollment season from Oct. 15 through Dec. 7.

Advantage plans have exploded in popularity in recent years as insurers have flooded the airways with advertisements, often by celebrity pitchmen, that promote low-cost options with lots of extra benefits.

But be aware that the federal government has deemed many claims in these ads fraudulent and misleading. Some ads imply that the Centers for Medicare and Medicaid Services endorses or prefers a specific plan. Others promise more cost savings than you really get. And if you choose the wrong plan, your doctor might not be a member of that plan’s network, or you could end up paying out of pocket for medically necessary care.

In September the U.S. Department of Health and Human Services began cracking down on these ads, but you still need to practice self-defense. Here are some tips to help you make a good decision.

>> Cover your needs: When evaluating Advantage plans, make sure the ones you are considering cover the doctors you like and the health care facilities you normally go to for your care. Also, make sure all of the prescription medications you take are on the drug plan’s formulary.

To help you compare plans, a good first step is to call the office managers of the doctors you use and find out which Advantage plans they accept and which ones they recommend. Then go to the Medicare Plan Finder tool at Medicare.gov/plan-compare to compare plans in your area.

>> Understand the details: Some Advantage plans promote no monthly premiums, but the reality is that you are still responsible for your original Medicare costs, including your Part B premium, and deductibles and copays for covered services. Moreover, you might have to pay more out of pocket if you see a doctor outside the network. Also, if the plan is an HMO, it generally doesn’t cover nonemergency care out of network, so a person may be responsible for full costs. A PPO, on the other hand, allows people to go out of network, but they generally have to pay more to do so.

>> Do some digging: Many Advantage plans tout free vision, hearing and dental benefits that are not covered by traditional Medicare, but these benefits are often limited. For example, a plan that offers free dental coverage might cover only cleanings and X-rays. Extensive procedures such as root canals or caps might not be covered, or the plan might limit the dollar amount it pays. Find out the coverage details so you’re not surprised later.

>> Get help: Reach out to your local State Health Insurance Assistance Program, commonly known as SHIP, at ShipHelp.org, or call 877-839-2675. These are nonprofit programs that provide unbiased one-on-one Medicare counseling and assistance.

You can also report any misleading Medicare Advantage claims to the Senior Medicare Patrol Resource Center at SMPResource.org or by calling 800-447-8477.

Jim Miller is a contributor to NBC-TV’s “Today” program and author of “The Savvy Senior.” Send your questions to Savvy Senior, P.O. Box 5443, Norman, OK 73070; or visit savvysenior.org.