St. John's Wort aerial parts extract gives you a standardized, concentrated form of the Hypericum perforatum plant. Manufacturers calibrate each batch to key compounds, usually hypericin or hyperforin, so you get a more predictable profile than you would from raw herb.
Many people take it to support emotional balance and a brighter mood during temporary stress. The typical form is a capsule or tablet. Taking it alongside food helps avoid stomach upset.
A serious warning: this extract speeds up how the liver clears many medications. It can weaken birth control pills, certain antidepressants, blood thinners (such as warfarin), heart drugs, and some HIV and cancer medications. It may also make your skin more prone to sunburn.