Same Drug Same Effects?

Since the biochemistry of psychoactive substances is usually the same for everyone we can assume that the same drug has the same effect on everyone…

BUT

  1. This does not mean that everyone experiences the effect the same way.
    The human brain has a great capacity of learning which also includes dealing with altered states. Therefore the same dose will not feel the same way taken a hundred times later…
  2. most of the times people sharing their drugs do not take the same amounts measured by bodyweight!
    so even sharing of drugs means that the smaller friends are getting a higher dose!