Most consumers know that when blockbuster medications go over-the-counter, pharmaceutical companies ramp up their advertising blitzes.

But what they may not realize is that health insurers often piggyback on that effort in an attempt to get members to try the over-the-counter alternative.

Such is the case with the popular heartburn medication Prilosec, which the Food and Drug Administration approved for over-the-counter sale last year.

Oxford Health Plans, one of the largest insurance carriers in New York, recently sent out letters notifying members who had taken a heartburn medication in the year prior that Prilosec was being sold “OTC” or over the counter. The insurer also included a glossy coupon from the manufacturer, Procter & Gamble, for a free 14-day supply of the medication, valued at $11.99.

An Oxford spokeswoman and another for the New York Health Plan Association, a trade group that represents managed care companies, said these kinds of mailings are a way to inform consumers of industry changes.

They said the letters do not require members to take the drug or switch from similar prescriptions, but instead increase consumers’ awareness about their options.

Others say the motives are murkier.

Health benefit consultants said mailings like Oxford’s are relatively common, but do advance dual agendas – one from health insurers, who have a financial incentive to move people to over-the-counter drugs they do not cover, and the other from pharmaceutical companies, which are striving for widespread marketplace recognition as their products shift into a new sales arena on pharmacy shelves.

“What they are trying to do is to give you a coupon so you will go out and buy the over-the-counter drug and you won’t incur an expense that is going to be seen by your plan,” said Sean Brandle, the pharmacy practice leader and a vice president at the Segal Company, a benefits and human resources consulting firm.

Like most in the health care industry, Mr. Brandle said, motivation aside, consumers often benefit when a drug goes over-the-counter because access is easier, especially for those with no prescription coverage, and medications can be cheaper.

Cost savings depend largely on prescription plans. When the popular allergy medication Claritin moved over-the-counter, many found themselves paying more for a one-month supply than they had for the co-pay on their prescription. And the same is happening, at least for some, with Prilosec.

Doctors say proton-pump inhibitors, or PPIs, the family of heartburn drugs like Prilosec, are effective and safe for over-the-counter use. But they are not surprised insurance companies found a way to tell consumers about Prilosec OTC.

“There are two ways that insurance companies are going to wind up saving a lot of money,” New York-Presbyterian Hospital/Columbia gastroenterologist Dr. Harold Frucht said. “One is that they won’t be responsible for paying for the medication. If the patient buys it over the counter it is coming out of the patient’s pocket. The other is that if people buy this stuff over the counter, they are not going to see their doctors.”

Oxford officials stress that Prilosec OTC is approved for “frequent heartburn” and that those who need the drug for other conditions can still get it as a prescription.

“It’s a business decision,” a Bronx pharmacist, Joel Zive, said. “I don’t particularly like it, but it’s not unethical.”