WASHINGTON -- A bill introduced Thursday by Sen. Jim DeMint, R-S.C., would make the cost of over-the-counter drugs tax deductible, a move that some think would make some drugs cheaper and more accessible.

Over-the-counter drugs, such as aspirin, allergy medicine, anti-fungal ointments and nutritional supplements, are not eligible to be deducted. Only prescription drugs, insulin and certain other out-of-pocket health-care costs can be deducted.

Medical-expense deductions apply only to taxpayers who rack up bills totaling at least 7.5 percent of their adjusted gross income. Deductions can be taken only on expenses that exceed the 7.5 percent threshold.

Only about 5 percent of all taxpayers qualify for the deductions, according to the Internal Revenue Service. It is unclear how many more taxpayers would qualify under the proposal.

DeMint estimated that the cost of the bill would be $1.6 billion over the next 10 years.

"We're looking to make medications less expensive and more accessible to people," DeMint said. "The more we treat over-the-counter drugs equally to prescription drugs, the more likely people are to have access to less expensive drugs."

DeMint tried to get same legislation through the House last year, but it did not clear committee.

DeMint, who co-sponsored the current bill with Florida Democratic Sen. Bill Nelson, said the legislation would "mostly affect families with incomes less than $25,000 a year and high medical costs due to chronic illnesses."

Recipients of Medicare and Medicaid are also eligible for the deduction. The Food and Drug Administration determines whether medicines are prescription or nonprescription.

In recent years, a number of prescription drugs have moved to over-the-counter, including antifungal medications, smoking-cessation aids and allergy combatants. According to the FDA, more than 700 products sold over the counter today use ingredients or dosage strengths available only by prescription 30 years ago.

Some pharmaceutical industry officials say the bill will increase competition among pharmaceutical companies, pushing drug prices down and allowing more prescription drugs to move over-the-counter.

"People are finding lower-cost, over-the-counter medications that work for them," DeMint said, "but in some cases, they choose the more expensive prescription drug because it's eligible for a tax deduction."

As soon as a prescription drug moves over-the-counter, taxpayers lose the medical-expense deduction. If over-the-counter drugs are subject to the same deductions as prescription drugs, some industry experts say more prescription drugs would move over-the-counter and into direct competition with similar medicines.

"The biggest benefit of this bill is to consumers -- especially seniors and lower-income Americans," said Mimi Pappas, spokeswoman for the Consumer Healthcare Products Association, a consumer drug advocacy group.

The bill comes on the heels of two IRS rulings in 2003 that made over-the-counter drugs eligible to be paid through tax-exempt flexible medical spending accounts and health savings accounts, both of which allow consumers to set aside portions of personal income for medical expenses not covered by insurance.

"This is proof," Pappas said, "that there's a growing chorus of federal agencies that are recognizing the importance of over-the-counter drugs in the public marketplace."