Need a method of getting the musty smell out of a mattress

[Kiwiinkits]

Hi there
we have a mattress in our spare room that actually really stinks. It has a lovely aroma of mustiness. I haven't tried Febreeze or anything like that yet. I just wondered, do you have any tips? Like, spray it with a mixture of lemon juice and baking soda or sommat?

air air air

do you have a garden or a balcony? then let it "live" there propped upright for a day or so.
or in the room with window wide open as often as possible.

can you remove the matress cover? can you see any stains (mold)? if yes, its time for a new matress...