The fate of a popular Southeast Asian plant product called kratom is uncertain following a Tuesday warning from the Food and Drug Administration, which says it’s seeking to stop imports of the tree leaf commonly used for pain management and addiction recovery.

Kratom tastes like green tea when it’s brewed and sometimes is taken as a pill. It comes from tropical trees related to coffee and users say it improves moods, gives an energy bump and alleviates pain. Proponents buy it online or at gas stations to treat arthritis, anxiety, and depression.