Energy drinks often have more caffeine than they advertise, a new report says.

According to a new study by Consumer Reports, very few energy drinks reveal the amount of caffeine present in the drink. The few that did do not state the correct amount of caffeine.

Of the 27 drinks studied, 11 did not contain information about caffeine levels, to keep their blends a secret. Of the 16 that did specify caffeine content, 5 had more caffeine than their labels declared.  Arizona Energy, Clif Shot Turbo Energy Gel, Nestle Jamba, Sambazon Organic Amazon Energy and Venom Energy had 20 percent more caffeine, the study reveals.

On the other hand, one of the three samples of Archer Farms Energy Drink Juice Infused had caffeine about 70 percent below the labeled amount.

The Consumer Reports study follows hot on the heels of a lawsuit involving Monster Energy drink and its connection to the death of five, including that a 14-year-old girl. Monster Energy has been one of the most popular energy drinks in the market for the last few months.

Several health advocates and a senator have been urging the FDA to place a limit on the amount of caffeine allowed in energy drinks.

The lack of such regulations, according to Consumer Reports, is one of the reasons used by companies to not mention correct caffeine content in their labels.

The company does not reveal levels "because there is no legal or commercial business requirement to do so, and also because our products are completely safe, and the actual numbers are not meaningful to most consumers," said a representative of Monster Beverage to Consumer Reports.

However, Monster Energy labels do warn a certain criteria of people not to consume caffeinated drinks.

The Report further adds that though safe limits for caffeine consumption are still being studied, data suggest that most healthy adults can safely consume up to 400 milligrams per day, while pregnant women can drink up to 200 milligrams. Children can consume up to 45 to 85 milligrams.

The Food and Drug Administration of the U.S. has now launched an investigation into the safety of consuming energy drinks.

Investors Wary of Monster Beverage

According to a report by the Wall Street Journal, investors have become wary of investing in the company's shares, thanks to it being embroiled in a lawsuit and being under FDA investigation.

After its connection to five deaths was revealed, its shares plunged 14 percent to $45.73. The shares have now dropped a combined 23 percent, reports WSJ.