  Erowid.org is a website dedicated to documenting information about
psychoactive substances, with over 36,000 user-submitted drug Experience
Reports. We study the potential of these reports to provide information about
characteristic experiences with drugs. First, we assess different kinds of drug
experiences, such as 'addiction' or 'bad trips'. We quantitatively analyze how
such experiences are related to substances and user variables. Furthermore, we
classify positive and negative experiences as well as reported addiction using
information about the consumer, substance, context and location of the drug
experience. While variables based only on objective characteristics yield poor
predictive performance for subjective experiences, we find subjective user
reports can help to identify new patterns and impact factors on drug
experiences. In particular, we found a positive association between addiction
experiences and dextromethorphan, a substance with largely unknown withdrawal
effects. Our research can help to gain a deeper sociological understanding of
drug consumption and to identify relationships which may have clinical
relevance. Moreover, it can show how non-mainstream social media platforms can
be utilized to study characteristics of human behavior and how this can be done
in an ethical way in collaboration with the platform providers.
