EXPERT: LIQUID MARIJUANA CAN BE EASY FOR TEENS TO CONCEAL

In Chapel Hill this week, four students were taken to the hospital after apparently overdosing.

One of the teens told ABC11 they thought they were using liquid marijuana but instead drank liquid ecstasy.

"You go to the drug store and buy Sudafed, you know exactly what's in it. When they get ecstasy or liquid marijuana, they don't know how much THC is really in that particular item. They don't know if it's mixed with something else," said Rebecca Wheeler, who is a substance abuse prevention health educator with the Poe Center for Health Education.

Liquid marijuana, or the chemical THC, can be bought in cartridges or extracted from marijuana plants.

It is often used in a vaporizer and can appear odorless and colorless making it easy for teens to conceal.