Slowly but surely, the Food and Drug Administration is expanding its efforts to reduce allergic consumers' exposure to sulfite chemicals used to preserve foods and drugs.

The agency today will issue a long-awaited proposal to require warning labels on prescription drugs that contain sulfites. The labels would advise that sulfites may cause mild to life-threatening reactions -- from hives to shock -- in some susceptible people, including asthmatics and other allergic individuals.

FDA says that the sulfite preservatives, used to prevent product deterioration from oxygen exposure, are found in more than 1,100 prescription drugs. Most are intravenous solutions such as antibiotics and local anesthetics and relatively few are drugs taken orally. Sulfites are used to preserve some asthma drugs and emergency preparations for allergic reactions.

The proposal, to be published in the Federal Register, would not apply to nonprescription drugs. There is also no requirement that nonprescription drugs be labeled to show that "inactive ingredients," including sulfites, are present, although the industry has encouraged voluntary labeling.

FDA spokesman Faye Peterson said the agency has had more than 500 reports of possible sulfite-sensitive reactions, including 13 deaths, largely traced to consumption of fresh foods preserved with sulfites. There have been 14 reports to FDA of sulfite reactions to prescription drugs, she said, but none among nonprescription drugs.

The FDA proposed Aug. 9 to ban sulfiting agents as preservatives for certain fresh fruits and vegetables used in restaurants and supermarkets. It is now reviewing comments on that proposal before issuing a final rule.

In addition, over the past six months, FDA has reported more than 30 recalls of dried fruit mixes and fruit-and-nut mixes that failed to label the presence of sulfites in the products.

All of the actions occurred after three years of pressure by consumer groups, scientists and members of Congress. The Center for Science in the Public Interest has pushed for stronger actions, including a ban on use of sulfites in drugs or stronger warning labels on drugs in which sulfites must be used.

BIG BUCKS . . . Possible misdemeanor fines under the Food, Drug and Cosmetic Act have risen dramatically. The maximum fine has been raised from $1,000 per criminal count to $500,000.

The new fines, set out in the Criminal Fine Enforcement Act of 1984, apply to violations of federal law that occur after Jan. 1, 1985. The Justice Department has advised the FDA that the general changes in the U.S. Code apply to laws enforced by the agency.

The new law allows a fine of up to $100,000 for a misdemeanor by a corporation or individual not resulting in death; up to $250,000 for a misdemeanor by an individual that results in death, or for a felony; up to $500,000 for a misdemeanor by a corporation that results in death, or for a felony. The maximum imprisonment for a misdemeanor remains a year for each offense.

When Eli Lilly and Co. recently pleaded guilty for failing to notify the government in 1981 and 1982 of numerous injuries and deaths overseas involving the antiarthritis drug Oraflex, a maximum penalty of $25,000 for 25 misdemeanor counts was imposed on the company. A former executive pleaded no contest to 15 violations adding up to a fine of $15,000.