Energy drink labels don't have to list how much caffeine they contain, although some companies do. Consumer and science groups have asked the Food and Drug Administration for labeling requirements, but the agency says it lacks the authority, according to Consumer Reports.
Safe limits of caffeine consumption are still being studied, according to Consumer Reports, but the prevailing recommendation says most healthy adults can safely consume up to 400 milligrams per day and children can safely consume up to 45 to 85 milligrams, depending on their weight. Pregnant women should consume no more than 200 milligrams per day.
Consumer Reports measured the amount of caffeine in some top-selling energy drinks and shots. Here's what they found: