WASHINGTON (AP) -- Food and Drug Administration officials have issued a warning letter to the makers of the inhalable caffeine product AeroShot, saying they have questions about its safety and concerns about how children and adolescents may use it.

AeroShot went on the market in January in Massachusetts and New York. Consumers put one end of the plastic canister in their mouths and breathe in, releasing a fine powder that dissolves.

The FDA said the Massachusetts company misled consumers by saying the product can be both inhaled and ingested, which is not possible. The agency said it is also concerned consumers may try to inhale it into their lungs, which may not be safe.

The letter also cited differing statements from the company on the appropriate age for using the product.