The Director of Mississippi’s Bureau of Narcotics says the state’s law requiring prescriptions for cold medicines containing pseudoephedrine, the key ingredient in methamphetamine, has reduced the number of meth labs in the state.

In the six months since the law went into effect, the number of meth labs has fallen by 70 percent, Marshall Fisher told the Register-Herald.

West Virginia is trying to pass a similar bill. The West Virginia Retailers Association, which represents stores including chain pharmacies, independent drug stores and groceries, opposes the bill. The group says an existing law that requires medications containing pseudoephedrine to be located behind the counter is effective.

Oregon requires a prescription for the tablet form of pseudoephedrine. Since Oregon instituted the law in 2005, meth labs have almost disappeared from the state, the Tulsa World reported in June.