It means that 20% of people will experience those side effects (it isn't only anxiety, there are more sideffects, see webpage)...
However, 20% may seem a lot, but in fact those very same side effects were also experienced by 17% of people who got a placebo (=a fake pill which does absolutly nothing) instead.
How can 17% of people get side effects if they didn't got any drugs administrated?... well, that's all in the head. This is what is called the placebo-effect. Give someone a fake pill and tell him it will cure his headache, and as if magic is involved here, the person's headache will be over... The mind is a powerfull thing
... Compare this to a mother who kisses on the achy of her child to
make it all better and achy is gone...
So, all this means that Abilify will not really endorse real physical side effects and is therefor quite safe (only an increase of 3% of people had real side effects).
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