St. John's Wort
After quitting a prescripted ssri for major depression, I started to use St. John's Wort to make sure I won't fall back into depression once again.
After several month of use I realized that not only my depression was gone, but my summertime - pollen allergies were also missing. (I didn’t take any of my prescripted anti-histamins.)
I searched through the internet, but haven’t found any mentions of St. John’s Wort having any anti allergy properties, so I started an experiment: I stopped taking it and the next day the good old allergy set in. When I took the alcohol based, over the counter extract again I could feel my allergies diminishing in about a half an hour. The summer and fall passed and I didn’t get any allergies again.
I found it very interesting and looking forward to next summer, when I’m planning to experiment on my buddies with allergies also.