While the price of almost any good or service can be found online, most Americans don’t know what they’ll owe for a prescription medication until they get it.

Unexpected costs contribute to the estimated 20 to 30 percent of prescriptions that are never filled, which can lead to health problems from untreated medical conditions.

“The best drug in the world isn’t going to be effective if the patient doesn’t take it,” said Dana Goldman, a health economist at the University of Southern California, whose research shows that patients have more trouble taking their medication as their costs rise. “Doctors need to think about, not just what’s clinically optimal, but what’s optimal given the patient’s financial circumstances.” The fix sounds simple: Give doctors information on patients’ costs before they write prescriptions. But companies have yet to design a system that can quickly analyze all the factors that determine what someone will owe.

The effort will soon get a push from the nation’s biggest health care customer: the federal government. Under a Medicare rule, companies with prescription drug plans for seniors must offer real-time pricing information by 2021.

COST-SHARING CONUNDRUM

Perhaps the biggest hurdle in calculating medication costs is the fact that doctors don’t know all the details about a patient’s insurance coverage.

Nearly 40 percent of people who get their insurance through their employer are required to pay for part of their medication, according to an industry survey. Many other patients have deductibles, in which they are responsible for paying all costs until they hit a set threshold. In those cases, patients can bear the full cost of pricey medications.

“Doctors often have no idea what it might cost the patient after insurance, if they have insurance,” says Lynn Quincy of the nonprofit health research firm Altarum.

IMPROVING INFORMATION

Despite current shortcomings, prescribing tools have come a long way since the days of paper pads.

Most major insurers and pharmacy benefit providers now offer cost-comparison information to doctors using online prescribing software. At a minimum, doctors should be able to determine if a medication is covered by a patient’s insurance.

For instance, CVS Health reported last year that prescribers using its real-time pharmacy benefit information saved patients $130, on average, for every prescription they switched to a lower-priced, covered drug.

But experts say additional features are needed.

Patients can often save money by not using their insurance at all and instead paying out-of-pocket for cheap generic drugs. In other cases, patients can get better deals by using coupons from drugmakers or pharmacies.

Those savings are flagged on smartphone apps like GoodRx but aren’t factored into physicians’ prescribing software. And even if they were, experts say doctors don’t have time to help patients figure out the best place to fill prescriptions.

“That’s why we want to put this information in the hands of the consumer, so they can do some of that research and shopping around,” said Pooja Babbrah, a health IT consultant with Point-of-Care Partners.

PHARMACY FUTURE

Babbrah and others envision a consumerfriendly app that pulls together patients’ prescribing and benefit details alongside local pharmacy prices and deals.

That has the potential to improve medication use for patients, lower costs for insurers and free up extra time for physicians.

But there are reasons to be skeptical.

Most insurers offer price information on certain medical procedures, but studies suggest only a tiny percentage of patients ever view it.

Surveys show Americans are interested in health care savings but are also “very intimidated by terms of insurance coverage,” Quincy said.

“They don’t really understand things like copays, coinsurance, deductibles and so they may lack the confidence to make use of these complex tools,” she said.