HOUSTON – Authorities said they raided three Houston smoke shops last week, seizing cannabidiol oil that contained synthetic cannabinoids.

CBD oil is an extract of the marijuana plant, but it lacks the intoxicating effects of the drug. It is usually extracted from the industrial hemp plant.

WATCH: Houston Police Department discusses CBD oil with synthetic cannabinoids

Houston police said the raids were the culmination of a monthslong investigation during which officers purchased CBD oil at several smoke shops, and that oil was tested in a lab. Police said the oil purchased at three shops was found to contain synthetic cannabinoids – the same chemical found in the illegal drug called Kush.

"If you have half a brain, you should not be using this stuff," Houston Police Chief Art Acevedo said.

Investigators said that many times, these types of drugs are made in the back of shops or in garages and are not tested before they are sold to the public.

Police said officers raided the following shops:

Fantasy at 1412 Westheimer Road

Smokey Doke at 5784 Bingle Road

Dreamerz at 2961 Bingle Road

Investigators said all three shops have been sued as being a nuisance and have been ordered to stop selling illegal substances.