The Food and Drug Administration said in a letter released on Tuesday that it was likely to seek advice from outside experts to help determine whether energy drinks posed particular risks to teenagers or people with underlying health problems.
The letter appears to signal a change in the agency’s approach to the drinks, which contain high levels of caffeine.
Previously, F.D.A. officials have said that they were investigating possible risks posed by popular products like 5-Hour Energy, Monster Energy and Red Bull. But an agency spokeswoman, Shelly Burgess, said the new letter was the first time that the F.D.A. had said it might turn to outside experts.
The F.D.A. letter, which was released Tuesday by Senator Richard J. Durbin of Illinois and Senator Richard Blumenthal of Connecticut, follows disclosures that the agency received reports of 18 deaths and over 150 injuries that mentioned the possible involvement of energy drinks.
The filing of such reports with the F.D.A. does not prove that a product was responsible for a death or an injury. Energy drink makers have said their products are safe and were not responsible for the health problems.
The officials said a review of the drinks might be “greatly enhanced by also engaging specialized expertise” from an outside group, like the Institute of Medicine, which is part of the National Academy of Sciences.
Industry analysts said the letter indicated that the F.D.A. did not plan any immediate actions on energy drinks, an interpretation that set off a rally on Tuesday in the stock of Monster Beverage, the producer of Monster Energy. Company shares closed at $51.97, up over 13 percent. Any regulatory outcome is likely to be “benign,” Judy Hong, an analyst at Goldman Sachs, said in a note to investors, according to Bloomberg News.
In Canada, however, the use of an outside panel led to limits on caffeine levels in energy drinks.
In their letter, F.D.A. officials indicated that an outside review would focus on the possible risks posed by high levels of caffeine, a stimulant, to certain groups. They reiterated that daily consumption of significant levels of caffeine, which is found in products like coffee and tea, is safe.
“Areas of particular focus would include such matters as the vulnerability of certain populations to stimulants and the incidence and consequence of excessive consumption” of energy drinks, especially by young people, F.D.A. officials wrote.
In Canada, an expert panel made several recommendations, including arguing that such beverages be labeled “stimulant drug-containing drinks.”
Health Canada, that country’s counterpart to the F.D.A., did not adopt many of the group’s recommendations, but it has put in place new rules limiting caffeine levels in cans of energy drinks to 180 milligrams.
Some larger-size cans of energy drinks sold in the United States, like the 24-ounce can of Monster Energy and the 20-ounce can of Red Bull, have caffeine levels above that limit.
An eight-ounce cup of coffee, depending on how it is made, can contain from 100 to 150 milligrams of caffeine.
In the new letter, F.D.A. officials also said that studies that had examined other ingredients, like taurine, that are often used in energy drinks had determined those substances were safe. The agency also said that a survey suggested that energy drinks constitute a small portion of the caffeine consumed in this country, even by teenagers.
