Patients like "patient package inserts" -- the leaflets that tell them the main benefits and frankly warn them about the risks of their prescription drugs.

But few change the way they use a drug or stop using it because of the warnings.

These are the main results of a $525,000, three-year study of the controversial inserts, or "PPIs." The study was made by the Rand Corp. and financed by the Food and Drug Administration, where some officials -- beginning in the Nixon administration -- began arguing that such leaflets should be given out with many powerful drugs.

Medical groups generally opposed the idea,. or said they approved it in principle but opposed any quick action.

In the Reagan team's new anti-regulatory atmosphere, FDA Commissioner Arthur Hull Hayes Jr. has held up a Carter administration experiment that would include PPIs with 10 drugs in addition to the four with which they are now required. The four are: birth control pills, estrogens for menopause, synthetic progesterone for infertility and other conditions, and the anti-asthma drug isoproterenol.

Hayes has endorsed the need for more information for patients and promised a decision by Jan. 1 on a package-insert experiment.

Those who oppose or question the value of inserts argue that patients might be alarmed by detailed warnings and stop using medications they need. The Rand survey of 1,821 people filling drug prescriptions at 69 Los Angeles pharmacies, however, revealed no such behavior.

The Rand experimenters either gave subjects one of several trial PPIs or enrolled them in a no-PPI control group for comparison; later they were queried.

The main findings:

Contrary to the claim of many doctors and pharmacists that "no one reads PPIs," most patients did read them. Among a drug's first-time users, 70 percent said they read them. Half the subjects said they kept them for reference, and 20 to 30 percent said they read them more than once. Patients generally said the inserts helped them understand drugs, know when to take them and follow their doctors' advice.

People did not imagine every side effect described -- another fear stated by opponents -- or increase their reporting of side effects to their doctors, except where the PPIs specifically told them to do so. Nor did the patients call or see their doctors more often. When they did, however, they were more likely to discuss drug safety and side effets.

Few patients changed their minds about taking a drug after reading the PPI. Only three of more than 2,000 prescriptions dispensed with PPIs were returned for a refund.