Background and aims: Ayahuasca is a dimethyltryptamine- and β-carboline-rich hallucinogenic beverage traditionally used by indigenous groups of Northwest Amazonian for ritual and therapeutic purposes. Animal and human studies suggest that ayahuasca has antidepressant and anxiolytic potentials and has a good safety profile. However, anxiety-like reactions may also occur after ayahuasca intake, although they are rare. Methods: Case report. Results: Here, we describe a case of a non-medicated, symptom-free young female with generalized anxiety disorder, who experienced intense anxiety, panic, and hopelessness during and for 3 days after participating in an ayahuasca ritual. The symptoms appeared in the first hours after ayahuasca intake and were gradually reducing in the following hours/days, but were intense enough to cause significant suffering to her, who needed to seek psychiatric help and restarted pharmacological treatment. Conclusions: Although “bad/horror trips” with anxiety features may occur during the acute effects of ayahuasca and other hallucinogens, to the best of our knowledge, this is the first report of a subacute/prolonged anxiety-like reaction to this substance. Ayahuasca should be used with caution in people with a history of anxiety disorders.