This study focuses on long-term negative psychological effects of psychedelic drugs, specifically targeting experiences that last more than 72 hours after use. This unique angle is driven by the necessity to balance the generally positive perception of psychedelics, especially regarding their therapeutic benefits, with a comprehensive understanding of their potential risks, particularly when used without proper supervision. Utilizing an online questionnaire and follow-up semi-structured interviews, the study aims to shed light on the less-discussed adverse outcomes of psychedelic use.Key insights from the study include the identification of anxiety and panic as the most common symptoms following psychedelic use, with many participants reporting new or exacerbated psychiatric symptoms. The study points to several factors that could contribute to these negative outcomes, such as the environment in which the drugs are used, pre-existing psychological vulnerabilities, the dosages consumed, and the age of the user. These findings emphasize the complex relationship between the psychedelics' capacity to enhance brain plasticity and the user's mental state, environment, and mental health history.For harm reduction and public safety, the study underscores the necessity of a balanced view on the use of psychedelics. While these substances have shown therapeutic potential in controlled environments, unsupervised use can lead to prolonged psychological harm for some individuals. The research highlights the importance of considering environmental safety, accurate dosing, and individual psychological health to reduce risks. It also stresses the need for more research to fully understand the frequency and causes of negative reactions to psychedelics, aiming to foster safer use practices and better support systems for those adversely affected. This study serves as a crucial reminder of the varied responses to psychedelics and the importance of caution and informed decision-making in their use.