A comprehensive survey of the scientific literature on direct-to-consumer advertising of prescription drugs has found substantial benefits—increased disease awareness and improved adherence among them—along with the risks of inappropriate prescriptions, worse health outcomes and higher public spending on drugs.

“The literature is so broad that when you take a bird’s-eye view, a few interesting things emerge,” said Dhaval Dave, associate professor of economics at Bentley University and a research associate for the National Bureau of Economic Research, which published the study.

Dave found a broad consensus that DTC advertising has both market-expanding and brand-specific effects, lifting all boats in a class while also benefiting the brand promoted. While that won’t surprise pharma folk much, the upside of consumer advertising that emerges from his review sounds surprisingly similar to the one the industry makes.

“There’s this view that advertising these drugs to consumers may not be a good thing, that it may disrupt the meditative process between patient and physician,” said Dave. “But at the same time, some studies show that when consumers are exposed to these ads, it may induce them to visit the physician, it may induce them to realize that there are treatments out there for their symptoms, and just that contact with the physician may be helpful. So that’s surprising, because a lot of organizations have focused on the negatives of these ads.”

Advertising works in part by altering consumer tastes and preferences—by setting the menu of available options. But healthcare is, much more than the world of tires, diapers and detergents, characterized by imperfect information. Drug ads, however skewed to sell a particular pill, help right that imbalance in several important ways. They tip off untreated and/or undiagnosed patients, particularly underserved patients such as those on Medicaid, to conditions they may have and the availability of treatments (particularly those annoying TV ads everyone complains to their Congressional representative about). They give a boost to compliance and adherence by reinforcing perceptions of the drugs’ effectiveness and reminding patients to take them. And they help drive patients to the doctor, resulting in increased patient-physician dialogue and diagnoses as well as sales. A 2005 study found that each $28 increase in DTC advertising leads to an additional physician visit within a year where a prescription drug from the advertised class is prescribed.

However, the literature also suggests that plenty of physicians are writing scripts for advertised drugs unnecessarily. A 2005 study that employed actors posing as patients found that those patients were prescribed Paxil in 27% of visits where they explicitly mentioned the drug and just 2% where they made a general request for the drug. One study, from 2010, even found increased adverse events reporting for drugs in highly advertised categories like arthritis and depression (the inverse was true for detailing, which appeared to reduce the adverse event rate for cholesterol and allergy drugs).

“That does suggest that there may be some persuasive element,” said Dave, “and in some cases where the treatment standards may not be that certain, there might have been better or cheaper treatment options available, or maybe it might have been better not to prescribe a drug. So there is both the benefit side and the cost side.”

One cost Dave didn’t find much evidence of was advertising-induced price inflation. One study even suggests that DTC drives down retail prices by spurring insurers and pharmacies to more intense price negotiations. Nor does DTC pose any barrier to entry by competitors, branded or generic—quite the contrary, as the manufacturers of all those blockbusters going over the patent cliff can tell you.