what are the side effects of using a deodorant with the active ingredient alumin!

Aluminium, present most often in antiperspirants, but not usually present in non-antiperspirant deodorants, has been established as a neurotoxin in very high doses. At high doses, aluminum itself adversely affects the blood-brain barrier, is capable of causing DNA damage, and has adverse epigenetic effects. Research has shown that high doses of the aluminum salts used in antiperspirants have detrimental effects to a number of species such as non-human primates, mice, and dogs.

Wow! I learned a lot. Here's the link in the source box for more info.

http://en.wikipedia.org/wiki/Deodorant#Aluminium_neurotoxicity

Some people think that long-term use of deodorants containing aluminum can increase your chances of getting Alzheimer's disease later in life.

For most people, short-term use of products containing aluminum will probably not going to have any negative health effects. However, since aluminum is a toxin and most of us use a deodorant on a daily basis, I would look for alternative deodorants.