DILBERT, a cartoon character, once strapped a barrel-sized mug of coffee to his back to keep himself alert. Americans who dislike coffee have other options. “Wired Waffles” come with caffeinated maple syrup. Übermonster Energy Brew can wash down Cracker Jack’d, a caffeinated snack.

But are such foods safe? This month America’s Food and Drug Administration (FDA) said it would scrutinise caffeinated products. San Francisco has sued Monster Beverage, a Californian firm, for marketing high-caffeine drinks to children. And Wrigley, a sweetmaker, said it would “pause” the launch of a caffeinated gum because of safety concerns.

American sales of energy drinks were $8.6 billion in 2012, about 12 times their level a decade earlier, according to Euromonitor, a research firm. (Sales in western Europe more than tripled, to $5 billion, over the same period.) Red Bull is America’s leader with 36% of sales. Monster has 29%; Rockstar, 8%.

Monster Energy and Rockstar are served in large cans with 160mg of caffeine. (A standard can of Coke has only 35mg.) The FDA says adults should imbibe no more than 400mg a day. More than that can increase anxiety and blood pressure. The number of American emergency hospital visits involving energy drinks doubled between 2007 and 2011 to more than 20,000.

So far caffeinated products have been lightly regulated. The FDA’s only explicit rule for caffeine dates from the 1950s and applies only to cola. But in 2010 it warned that adding caffeine to alcoholic drinks promoted “risky behaviour”, since drunks who stay awake have more time to do something stupid. Phusion Project, a maker of buzzy booze, stopped.

Now the FDA is threatening stronger regulation. Monster’s net income fell by 17% in the first quarter, compared with the same time last year, partly because of regulatory troubles. The added scrutiny is somewhat unfair. A large coffee from Starbucks has more than twice as much caffeine as a can of Monster. Yet no one is standing between Americans and their morning cuppa joe.