The order comes on the heels of last year's discovery by the FDA that active ingredients from medicine for erectile dysfunction were found in over-the-counter supplements.
Lesser improprieties include vitamins not containing the printed amount. The FDA is trying to crack down on both kinds of gaffes, according to the Associated Press.
Some say the new rule is still not doing enough to police the $22 billion industry.
"Consumers still have no idea if a given product works, or whether it is dangerous," said Janell Mayo Duncan, senior counsel for Consumers Union, publisher of Consumer Reports.
For lesser infractions the agency could ask the manufacturer to remove an ingredient or revise its label. In more serious cases, it could seize the product, file a lawsuit or seek criminal charges.
The new rule has a three-year phase-in that begins on Aug. 24 for smaller companies. The largest manufacturers have to comply by June 2008.
