A recent consumer report says most of energy drinks incorrectly list the amount of caffeine in their product, or do not list the amount at all. The magazine tested 27 popular energy drinks and shots, and calculated the amount of caffeine in one serving, based on the manufacturer’s serving size.

Of those products, 16 listed specific caffeine amounts. Five products—Arizona Energy, Clif Shot Turbo Energy Gel, Nestle Jamba, Sambazon Organic Amazon Energy and Venom Energy—had 20 percent more caffeine per serving than stated on the label. Archer Farms Energy Drink had 70 percent less caffeine than indicated on the label. The caffeine levels of the remaining products fell within 20 percent of the amount stated on the label.

The U.S. Food and Drug Administration (FDA) is investigating reportsthat five people have died since 2009 after they consumed Monster energy drinks. The investigation was announced after parents of 14-year-old Anais Fournier sued the company in connection with their daughter’s death.