The whole of the aboveground parts of the plant collected during the flowering season are used to make the various forms of the herb.
The activity of St John’s Wort varies a lot depending on when it is harvested and how it is stored. Research says that the most active forms are tablets rather than capsules or liquids.
It is widely used to treat mild to moderate depression. It has been called "Nature’s Prozac" and has fewer side effects than prescription anti-depressants.
It is also used for seasonal affective disorder (SAD), anxiety, listlessness, sleep problems, and is being tested as a possible part of the treatment for HIV and AIDS.
In lotion form St John’s Wort improves the healing of wounds, bruises, varicose veins and mild burns.
The accepted dose is 300 mg taken three times a day for mild depression, but doses of up to three times that have been used.
All anti-depressants (both herbal and prescribed) take some time to get into the brain and have an effect. St John’s Wort can take two to four weeks and up to six weeks in some cases. Therapy should continue for at least six months after you feel better, then the dose can be gradually reduced.
Side effects are usually mild. Possible problems include abdominal pain, bloating, constipation, nausea, vomiting, dry mouth, itching, skin rashes, restlessness, tiredness, raised blood pressure and sensitivity to sunlight. (This is as nothing compared to prescription anti-depressants.)
St John’s Wort may reduce the effects of prescription drugs, so get advice if this is a possibility.
You must see your doctor if you are suffering from severe depression — St John’s Wort is not the answer in this case.