Some research shows that rubbing stinging nettle leaves on painful joints can provide pain relief. One small study also found that eating stewed nettle leaves was a helpful addition to taking the anti-inflammatory drug diclofenac. People have also used stinging nettle as a diuretic -- a treatment that causes the body to shed more water in the urine. Research has found this effect from stinging nettle in rats. But there's no standard dose for any condition, and you should talk to your doctor first.