Lion’s mane (Hericium erinaceus) mycelium and its compound erinacine A reduced ketamine intake and motivation in male rats trained to self-administer 0.5 mg/kg/infusion. At higher doses, lion’s mane mycelium lowered ketamine-seeking behavior without reducing food reinforcement, while isolated erinacine A also reduced food reward. This is strong mental-health-adjacent mushroom science, but the evidence is preclinical, not human ketamine therapy data.