Damiana had served as the "base leaf" for banned synthetic cannabis products and would therefore have the same smell and taste.
The staff member predicted the products' potency would be increased in future and other plants could be added to them.
Psychoactive Substances Regulatory Authority manager Dr Donald Hannah said Tai High, which he described as "a smokable product that contains damiana", was not considered a psychoactive substance under the Psychoactive Substances Act.
"It is now illegal to sell products containing psychoactive substances. There are no approved psychoactive products, if a product is being sold as a 'legal high' the onus is on the product."
The Psychoactive Substances Amendment Act, which became law last month, removed all psychoactive legal high products on the market after it was passed under urgency.
Police would like to hear from anyone who knows of party pills or synthetic cannabinoids or any related psychoactive product being sold from any premises. People can call the psychoactive substances hotline 0800 789 652 to report a concern or seek advice.