Muskimol is sold in the form of candy and e-cigarettes, among other things, and can lead to serious poisoning.
The Public Health Agency has wanted to have the substance classified as a narcotic and the government's decision is based on the authority's documentation.
In addition to muscimol, nine additional unregulated substances will be classified as narcotics. The narcotics classifications will come into effect on December 30.
"The classification is a necessary step to reduce risks and protect public health," says Minister of Health Elisabet Lann (KD) in a press release.
Among the substances are two synthetic substances that are similar to mitragynine, a component of the kratom plant. The substances are associated with a high risk of addiction and can cause severe poisoning.
The drug classification means that the substances may not be imported or possessed without special permission from the Medical Products Agency.
Corrected: In an earlier version of the text there was an incorrect description of how far the process of classifying the substances as narcotics has come.
