Some people have problems finding a natural deodorant that agrees with their skin type. Possibly you are a candidate for using lime fruit as a deodorant? But beware, limes have potential side effects! One side effect occurs when your skin is exposed to ultraviolet light. A reaction can occur called asphytophotodermatitis, which leads to blistering, darkening or swelling of the skin (Wikipedia).
Another side effect is that some times the juice of limes can slightly irritate the skin, causing a red rash. I’ve had this occur before.
Usually fresh limes do not work the first day and it can take up to 3 days for your pH to adjust. Try taking a shower and scrubbing your underarms gently with a lime. Thus starting with fresh and clean armpits. You could experiment on just one armpit and see if that works before full commitment.
To try a lime as deodorant. Just slice in half and rub the inner fruit juice onto your armpit.
How long can you expect to stay fresh using limes? Past experience for me was about 6 to 8 hours at the maximum.