When bacteria living in shoes and socks interact with perspiration from the feet, foot odor occurs, according to the American Academy of Podiatric Practice Management. Excess perspiration in the feet can be caused by hormonal changes, fluid intake, certain medications and stress.
Practicing good foot hygiene can reduce the levels of bacteria in shoes and socks, and wearing thick socks can help to wick moisture away from the feet. Allowing shoes to dry out for 24 hours after wearing them and alternating wearing of shoes between several pairs can also help stave off foot odor. Soaking the feet in black tea can kill off the bacteria that cause foot odor, according to the AAPPM.