Yes I've tried this before and it works!

Clean your helmet - "To make a stinky helmet fresh again wear it in the shower! Get a good shampoo lather going on your head, put your helmet on and massage your scalp with the helmet for a few minutes. Then, give it a good rinse." Tom Smith, NY

Source: Cycling Tips/ bikyle.com

Clean your helmet

"To make a stinky helmet fresh again wear it in the shower! Get a good shampoo lather going on your head, put your helmet on and massage your scalp with the helmet for a few minutes. Then, give it a good rinse."
Tom Smith, NY

Source: Bikyle.com, Cycling Tips.