[1] Bromethalin works by being metabolised to n-desmethyl-bromethalin and uncoupling mitochondrial oxidative phosphorylation, which causes a decrease in adenosine triphosphate (ATP) synthesis.

The decreased ATP inhibits the activity of the Na/K ATPase enzyme, thereby leading to a subsequent buildup of cerebral spinal fluid (CSF) and vacuolization of myelin.

All intentional ingestions for self harm carry significant risk of death or severe neurologic effects and require monitoring in a hospital setting.

[3] In humans the most common initial effects of unintentional exposure are nausea, vomiting, abdominal pain, and diarrhea, though delayed seizures have been reported.

In pets, signs to watch for include severe muscle tremors, hyperexcitability, fits, extreme sensitivity to being touched (hyperesthesia) and seizures that appear to be caused by light or noise.