Treatment with the stress hormone cortisol can help arachnophobic patients conquer their fear of spiders, according to a US study. The researchers gave either 10mg oral cortisol or a placebo to 20 arachnophobic patients. Those given cortisol reported less fear than the controls when looking at a photograph of a spider one hour later, and still had less fear when looking at a spider two days later. The researchers concluded that cortisol helps reduce phobic fear by inhibiting the retrieval of fearful memories associated with the phobia. However, they found the treatment did not reduce general, unrelated anxiety (PNAS 2006;106:5,585-90).