Introduction: Memantine, an NMDA receptor antagonist indicated in the treatment of Alzheimer’s disease, presents pharmacodynamics similarities with commonly misused and diverted drugs including ketamine and dextromethorphan. However, there is, to our knowledge, no description of such practices with memantine. The objective was to characterize the consumption practices of memantine by implementing a netnographic study. Methods: We performed a netnographic study by applying ethnographic methods to publicly available online content of web forums. We identified the memantine users’ experiences posted on English and French-written web forums. We anonymously extracted all related discussion threads, posted anytime until July 2019, except those reporting experiences in Alzheimer’s disease. A qualitative thematic content analysis was performed. Results: We included 128 discussion threads from 5 websites: reddit.com (n=104); drugs-forum.com (n=9); erowid.org (n=8); bluelight.org (n=5) and psychoactif.org (n=2). We classified the related content in six themes: i) Products, sourcing and decision making (n=31); ii) Motivation for use (n=95); iii) Route of administration and doses (n=70); iv) Perceived effects and outcomes (n=109); v) Comparison or combination to other drugs (n=30); vi) Tolerance and abuse potential (n=23). When details were available, users were mostly males, aged between 18 and 27 and experimented recreational drug users. They reported using memantine for therapeutic purposes or in search for recreational, dissociative effects; and described a limited abuse/addiction liability due to pharmacological features perceived as detrimental for misuse and to the easy access of more attractive substances. Discussion: Our analysis highlighted two types of uses, either motivated by recreational or therapeutic purposes and characterized by broadly different practices. Although of lower magnitude than those observed with other dissociative drugs, memantine misuse and diversion practices exist and are shared online by users. The use of an innovative online ethnographic method is useful to describe previously unknown drug consumption practices from the users’ perspective.