Some 45 million people are about to lose a key tax break in health care. Starting in January, they'll have to get what amounts to a prescription from a doctor in order to get reimbursed for over-the-counter medications such as cold and flu remedies or allergy medicines.

Robert Zirkelbach of America's Health Plans, an industry group, says, "The changes are going to add an unnecessary cost to the system and make it more difficult for patients to obtain medication they currently rely on."

Those millions of Americans are getting notices that, beginning with the new year, pre-tax money they set aside for flexible spending or health savings accounts can no longer be used for over-the-counter drugs. That is, unless a doctor writes what amounts to a prescription.

Chris Krese of the Association of Chain Drug Stores says, "We are talking about 15 thousand over-the-counter products that are now subject to this new policy."

Items that fall under the new law include Tylenol, remedies for stomach ailments, cold and cough medicines, allergy medications and many, many others.The drugstore association is asking the federal government to delay the rules for at least two years "in order to carry this out in a way that minimizes consumer confusion."

One of the complications of this policy is that the only way people can get reimbursed for over-the-counter drugs will be to make an appointment with their doctor and get a sort of prescription for the drugs in question in order to qualify for flexible spending money.

Ed Haislmeir of the Heritage Foundation says this means, "The doctors are going to have to charge you for an office visit."

That adds to the cost of health care for those who would otherwise treat themselves for minor ailments.

And Robert Zirkelbach of the insurance industry says, "That's going to add cost at the doctor's office, that's going to take time out of my day."

Not only that, but with chronic conditions such as allergies, it might be cheaper to get a prescription drug -- if your health plan has a reasonable co-pay.

"So you'd be inclined to go with the prescription drug that might in the end have a higher total cost, but you pay a lower share of that total cost," says Zirkelbach.

That is likely to mean a higher cost for the employer but not the individual. Zirkelbach says that creates a perverse incentive "for me to use a higher cost prescription medication instead of using more affordable over-the-counter medication that works just as well."

Bill Sweetnam, of the Groom Law Group, worked at the U.S. Treasury Department during the Bush years and was instrumental in expanding FSAs. He says, "The impact will be that the people will use their FSAs a lot less, less than they used to and that's unfortunate because it is such a good tool."

So a law intended to reduce national health expenditures overall may actually end up increasing them, even as it takes more money from the pockets of taxpayers.

Jim Angle currently serves as chief national correspondent for Fox News Channel (FNC). He joined FNC in 1996 as a senior White House correspondent.