Star anise comes from the dried, star-shaped fruit of the Illicium verum tree. People use it as a spice, steep it as tea, or take it in extract or powder form. It supports digestion and helps ease occasional gas and bloating. The fruit also supplies shikimic acid, a compound used when making the antiviral drug oseltamivir (Tamiflu).
Culinary amounts are generally safe. Be careful with concentrated extracts or supplements. Safety data during pregnancy and breastfeeding is lacking, so avoid use then. Some products get mixed up with Japanese star anise (Illicium anisatum), which is toxic. Confirm any supplement or spice comes only from Illicium verum. Large doses can trigger nausea or allergic reactions.