Nutrients/Active Ingredients: Thought to have the compounds hypericin and hyperforin.  They are thought to inhibit neurotransmitters like dopamine, serotonin, norepinephrine, and GABA. Lower levels of these compounds are thought to lead to depression.
Uses by system and symptom: 
Digestive/Gastrointestinal:  Has been used for peptic ulcers and gastric problems.
Integumentary/Skin:  Has been used to treat wounds, bruises, burns, and sores.
Muscular: Has been used for muscle pain, arthritis, and gout.
Respiratory:  Has been used for congestion and chest colds.
Urinary:  Used as a kidney detoxification, diuretic, and childhood bedwetting. 
Nervous:  Most commonly used for neuralgia, Bell's Palsy, nerve pain, mild depression, restlessness, anxiety, and insomnia. Often used for Seasonal Affective Disorder (SAD) and with lemon balm for Obsessive Compulsive Disorder (OCD)
Immune:  thought to have antiviral qualities.
Male/Female Reproductive:  Used for PMS and menstrual cramps
Other:  Has been used for opiate withdrawals and smoking cessation
Common doses and preparation: Most commonly taken as liquid extracts, pills, and teas.  It may take weeks or months before you notice any effect.
Side Effects/Precautions/Interactions:  Not recommended for bipolar disorder or people taking medications called SSRI. May interact with multiple medications.
* This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. For educational purposes only. We recommend speaking with a physician or health care professions, especially if you have medical conditions, are pregnant or lactating, on medications, or use with children and infants.