A medical advisory panel told the Food and Drug Administration in a report yesterday that makers of aspirin and other pain-relief drugs should be required to cut down on claims and add warnings of possible dangers on their labels.

The 1,200-page report was part of a five-year study FDA is making of the safety and effectiveness of non-prescription drugs sold over the counter. The panel spent four years reviewing ingredients and labeling used in 50,000 brand-name products sold to give temporary relief from pain.

It probably will take another two years of public hearings and refining before the FDA issues regulations to the industry. FDA Commissioner Donald Kennedy told a news conference yesterday.

The panel found that the two main pain-relievers aspirin, aspirin and acetaminophen, are safe and effective when properly taken and that aspirin also helps reduce body-joint inflammation. But it said purchasers should be warned of possible dangers on the label of each container.

For instance, the panel said neither drug should be used to give relief from arthritis except by direction of a physician. This is a chronic disease and should not be the subject of self-treatment, the panel said.

Aspirin should not be used in the final three months of pregnancy or if it causes ringing in the ears, the panel also said.

Acetaminophen (sold under trade names of Valadol and Tylenol among others) can cause liver damage if used in excessive doses, the panel found.

It recommended that each bottle of pain relief pills make no greater claim than that it is "for the temporary relief of occasional minor aches, pains and headaches and for the reduction of fever." Individual claims of providing relief for specific ailments should not be permitted because all do about the same thing, the panel concluded.

The label proposed by the panel for each bottle of aspirin consists of more than 300 words of directions and warnings, six times as many as on the label of a bottle of aspirin on a store shelf today.

Dr. J. Weldon Bellville, who chaired the panel, was asked if this wasn't too many words to fit on a small bottle and be readable. He replied that the panel felt every word as essential.

"I'm sure manufacturers will find a way." he said.

Kennedy added that this was a problem and that "something may have to be dropped." There will be two rounds of public comment before FDA makes a decision, he said.

The panel recommended that phenacetin, an ingredient in some over-the-counter pain-relief drugs, be made a prescription drug because chronic use can cause liver damage.

Kennedy predicted that the report will lead to "more explicit labeling and essential new warnings." He said he expects that "the all-too-prevalent addiction to adjective-itis and misleading comparisons will other products will disappear" from advertising.

The Proprietary Association, which represents manufacturers of over-the-counter drugs, issued a statement saying the proposals would deny consumers information about what different pills are intended to relieve.

FDA should not "unreasonably limit specific and supportable claims for pain-relieving," the association said.