Hydrangea is a genus of shrubs grown throughout much of the United States, Europe, Asia, and other areas with a suitably moist climate. They flower in late summer through early fall, producing a profusion of blue, pink, and white blooms larger than a fist and roughly spherical in shape. Aside from being cultivated for ornamental shrubs and hedges, hydrangea have long been regarded for the medicinal properties of their roots. Never use hydrangea for medicinal purposes, however, without consulting your doctor first.
The two substances unique to hydrangea are known as Hydragenol and Hydrangeaic acid. Both have a number of effects. The first and foremost is as a diuretic, and to some small extent an anesthetic. For this reason hydrangea roots may be used to help clear the urinary tract of kidney stones and gravelly discharge while dulling the pain of their release. This does not extend to gallstones, as it does not affect the gallbladder.
Because kidney stones, and indeed the entire urinary tract, start with the kidneys, Hydragenol causes the kidneys to release sodium and stimulate urination. A side effect of this is to help treat kidney infections by cleaning out infected cells and bathing the infected area in sodium.
Hydrangea has been used as an anti-inflammatory, though the exact means in which it does so has not been fully explored. As the inflammation tends to benefit welts, bruises, and particularly the prostrate gland, it's thought that hydrangea reduces the content of fluid masses in the body. This would classify it as a desiccant, which is conducive to the fact that it's already an established diuretic. This is as opposed to an anti-inflammatory, which breaks up the presence of leukocytes in the affected tissues. For these reasons, hydrangea might be used to treat water retention problems.
Bladder infections may be caused by bacteria such as E. coli, which normally live in the gastrointestinal tract, or by fungi like Candida albicans. These are usually kept in check by the body's beneficial bacteria, but in cases where antibiotics are used, this beneficial bacteria is non-existent. Hydragenol and Hydrangeaic acid increase the amount of urination as well as the sodium and ammonia content of urine, which aid in killing and flushing out these infectious organisms.