FDA Tightens Guidelines on Drug Labeling : Consumers: New rules require stronger warnings on over-the-counter antacids, laxatives and anti-diarrheals.

Over-the-counter antacids, laxatives and anti-diarrheals must carry stronger warning labels about possible interaction with other medications under rules issued Thursday by the Food and Drug Administration.

The FDA also proposed that warnings be clarified on sleep aids and other non-prescription drugs used to treat nausea and vomiting.

The FDA said the revisions for non-prescription laxatives and diarrhea medications are necessary because of potential harmful interactions when the drugs are taken with other over-the-counter products.

The labels will also advise consumers to drink adequate fluids when taking laxatives and anti-diarrheal medicines that contain water-soluble gums, according to the FDA.

From 1970 to 1992, the agency had reports of about 200 cases, including 18 deaths, of such products causing choking or obstruction of the esophagus.

Changes were proposed for over-the-counter sleeping pills and anti-nausea drugs, the FDA said, because the antihistamines they contain can have an adverse effect on people with glaucoma, emphysema or other breathing problems, or urination problems caused by an enlarged prostate gland.

The proposed changes are part of ongoing FDA efforts to revise and clarify labels, the federal agency said.

“It’s part of a regular review,” said Arthur Whitmore, an FDA spokesman. “There will be other labeling changes on other over-the-counter drugs.”

Some companies in the industry said they have not yet reviewed the specifics of the new warning labels, but a spokesman for an industry group said companies wholeheartedly support proper labeling programs.

“It’s in our best interest for people to take medicines the way they should,” said Frank Rathbun, spokesman for the Non-prescription Drug Manufacturers Assn.

Industry analysts say the changes should not affect sales of non-prescription drugs, many of which have been on the market for years and have earned loyal followings.

“Requirements such as this generally don’t have an effect on consumption,” said Steven Gerber, an analyst with Oppenheimer & Co.

But he does question the effectiveness of new labels. Consumers who have regularly used a product are probably not going to reread the labels, Gerber said.

Yet the FDA will probably continue such efforts to revise and expand its regulations, he said.

“I think the agency sees itself as much more pro-consumer than it has in the past,” Gerber said.