BOSTON -- Energy drinks have been popular for years, promises to give you that extra boost to get through the day. Now there's a new trend in the beverage world.

An anti-energy drink has hit the Boston market. Some call it "liquid pot" or "weed in a can," but some doctors question its safety.

"I'll have four or five clients first thing in the morning," said Brad Cardoza, a owner of Pinnacle Strength and Fitness in South Dartmouth, Mass.

Cardoza is a hands on fitness trainer who pushes his clients through extreme workouts.

"I'm very high stress, high anxiety, speed speed speed," he said.

To help him wind down at the end of the day, he grabs a carbonated grape-flavored soda with the words "slow your roll" on the can.

"Drinking something like that, I'm definitely going to feel it," Cardoza said.

Drank is an anti-energy beverage claiming to be the ultimate relaxation drink. Some refer to it as "liquid pot", or "weed in a can". Yet it contains no drugs and is perfectly legal. Its makers claim it's made with an all natural blend of melatonin, valerian root and rose hips, ingredients known for their calming effects.

"This little cocktail is a little bit frightening," said Dr. Cathleen London, of Brookline, Mass.

London has concerns with the drink. She warned it is packed with sugar, and the main ingredients come with risks.

She said rose hips and valerian root have been linked to side effects such as headache, nausea, even disrupting sleep. But London's biggest concern is with the herb, valerian root.

"It's not something you want to be using on any kind of continual basis because it has been associated with liver damage," she said.

The Food and Drug administration told NewsCenter 5 that valerian is an approved food additive and rose hips are generally regarded as safe. But the FDA says, "melatonin has not been approved for use as a food additive."

London added that the hormone is used to treat jet lag and insomnia. She said melatonin and Drank should only be taken when you're ready to go to sleep.

"This is the equivalent of taking a valium and going for a drive," London said.

Drank does have a warning label that says it may cause drowsiness, and it's not recommended you have more than two servings a day. The makers of Drank said they've sold millions of cans with no reports of adverse effects.