[3] Examples of trip killers, in the case of serotonergic psychedelics, include serotonin receptor antagonists, like antipsychotics and certain antidepressants, and benzodiazepines.
[6] Accordingly, the serotonin 5-HT2A receptor antagonists ketanserin, an antihypertensive agent, and risperidone, an antipsychotic, have been shown to block the effects of serotonergic psychedelics in clinical studies.
[2][4][5] The most commonly encountered putative trip killers in a 2024 online study of Reddit social media postings were the benzodiazepines alprazolam and diazepam, the antipsychotic quetiapine, the antidepressant trazodone, and alcohol.
[3][31] While employed by recreational users for harm-reduction purposes, the use of trip killers to abort the effects of psychedelics and other hallucinogens is not fully characterized and could pose medical risks.
[1][4][5][27] Other serotonin 5-HT2A receptor antagonists that may block or reduce the effects of serotonergic psychedelics include other antipsychotics, like pipamperone, other antidepressants, like mianserin, nefazodone, and etoperidone, and the antimigraine agent pizotifen, among others.
[32] Conversely, in spite of variably acting as serotonin 5-HT2A receptor antagonists, tricyclic antidepressants (TCAs), including desipramine, imipramine, and clomipramine, have paradoxically been reported to potentiate the effects of serotonergic psychedelics rather than diminish them.
[6] Other drugs that have been reported to potentiate rather than inhibit the effects of serotonergic psychedelics include lithium, reserpine, pindolol, and methysergide.
[33][34] High-dose nicotinic acid (niacin, a B3 vitamer) was reported to reduce and block the effects of LSD in one early clinical study.
[8][48][49][50] Although clinical management of antimuscarinic deliriant intoxication and poisoning, for instance due to scopolamine, is usually supportive, acetylcholinesterase inhibitors, such as physostigmine, have sometimes been used in this context as well.