There are many an anecdote about making the switch to an aluminium-free deodorant after using an anti-perspirant. But, in reality it doesn't have to be anything scary - as long as you're prepared for the detox process.
While you'll often hear people claiming that 'natural deodorants just don't work for me', this is rarely the case. In reality, they just didn't give their body long enough to work through the transition from aluminium to aluminium-free. Natural deodorants aren't making you smell worse, they are just adjusting the levels of odour-causing bacteria in your underarm for the better.
Remember, it's not your sweat that smells, it's the bacteria living in your armpits.