Another group of legal products that are widely available can be used to mimic the effects of marijuana. With names like Spice and K2, the synthetic drugs are popular enough to warrant dozens of YouTube videos devoted to them.
But Dr. M. David Lewis, Medical Director at the Visions Treatment Center in Malibu, Calif., said those drugs can be especially dangerous for teens.
"K2 and Spice are tremendous psychoactive drugs," Lewis said. "And if you take a developing brain... what you really have is a chemistry experiment."
Drug treatment centers across the country reported they are being flooded with teens who have become addicted to drugs like K2 and Spice. Since 2010 alone there have been 4,000 calls into poison control relating to the drugs.
After 18-year-old David Rozga of Indianola, Iowa, suddenly took his own life with a rifle last year soon after graduating high school, his parents were convinced the synthetic drugs played a major part.
"He just continued to become agitated -- indicating that he felt like he was in hell," David's father Mike Rozga said. His girlfriend at the time said it was clear David was under the influence of something.
"David did not do this intentionally," girlfriend Carrie Jackson told ABC News. "He was like in an altered state and, you know, he would never do this or hurt us or hurt anyone else or hurt himself."
Mike Rozga said before his death his son went to a local mall and legally purchased K2.
Retailers say they have their own standards and most won't sell to anyone under 18. But ABC News hidden cameras caught two retailers -- one in New York City and one in Los Angeles -- selling Spice to a 14- and 16-year-old, respectively, without ever asking for ID.
Retail store trade groups say that as long as the products are legal -- and there is no federal regulation banning the chemicals -- there is no reason not to sell it. Dan Francis of the Retail Compliance Association said the products are nowhere near as dangerous as some foods that trigger allergies.
"It's not a dangerous product, much less dangerous than, say, peanuts," Francis said. "A ban is dangerous... because it sends it underground. And I'd like to ask the government what is wrong with euphoria and who gave them the right to regulate it?"
However, Detective Sergeant Brian Sher, who investigated David Rozga's death, places the blame for the boy's death directly on K2.
"I want people to know that," said Sher. "There are nay-sayers, but I can say definitively there's just nothing in the investigation to show that. Given what we know about K2 and Spice, David's anxiety, his feeling like he was in hell, has happened in many other cases."