WASHINGTON -- Ask a doctor for a prescription drug you saw advertised on TV, and 69 percent of the time you'll go home with it.

That's what the Food and Drug Administration just discovered in a survey that illustrates how big a role advertising plays in the doctor's office.

Is that necessarily bad? Critics bemoan the findings while proponents say drug ads help more sick people find treatment -- but the FDA still is struggling to uncover the true public health impact of the nation's barrage of drug ads.

"The question is: Are people getting drugs that actually aren't appropriate?" says FDA drug chief Dr. Janet Woodcock.

She doesn't yet know. But the FDA now is studying why doctors prescribe the way they do, a first step toward answering that question. And the agency is considering if some of the rules that govern how powerful medications are advertised need changing to ensure consumers better understand a drug's pros and cons.

Expecting a miracle?

It's a complex issue. Doctors have to decide more than yes or no when a patient demands a drug by name. Does the patient expect a miracle because the ad overpromised a pill's benefits? Is there an alternative that works better, more safely or is cheaper? Cheaper drugs typically don't rate a commercial, while the hottest-selling newer drugs -- like arthritis treatments Vioxx and Celebrex or heartburn medicine Prilosec -- are among the most heavily advertised.

Then there's the trickier question of who an ad targets. The National Medical Association, which represents black doctors, says direct-to-consumer drug ads can prod people reluctant to visit a doctor to do so -- especially black Americans, who are less likely to get appropriate care.

But today's ads aren't living up to that potential, the NMA said this month as it issued what is for a health group a startling call for more drug ads -- in media outlets that target minorities, and with more culturally diverse commercials.

Manufacturers once advertised prescription drugs mainly to doctors. Then in 1997, the FDA loosened its drug-promotion rules and suddenly advertising aimed at ordinary people tripled to nearly $2.5 billion a year.

Now the FDA's new survey of 943 people who saw a doctor in the last three months adds to the debate: Only 5 percent said a drug ad spurred them to go to the doctor. Once there, 69 percent who asked for a particular drug got it.