I have seen no references to any negative side effects for DMAE.
Remember, the result of taking DMAE is to increase the amount of
choline available to the brain AND choline is a natural substance
produced in the brain, so it's not like it's really a drug, it's more
like a 'vitamin supplement' for the brain.
Most of the questions related to DMAE that I've seen deal with the
question of the proper dose to achieve some noticeable effect. The
conservative recommendation is 100 mg per day, which is usually the
amount in one capsule. DMAE is often combined with B vitamins in
prepared capsules. For stronger effects, I think the recommendation
300 mg per day in three doses. At this level you might get a
noticeable 'buzz'.
Mark