Lion’s mane mushroom is not known to cause depression in clinical studies. In fact, the available human and animal research consistently points in the opposite direction, showing reductions in depression and anxiety scores. However, there are a few biological mechanisms worth understanding that could, in theory, produce negative mood effects in certain individuals.
What Clinical Trials Actually Show
The human evidence on lion’s mane and mood is limited but consistently positive. In a clinical trial of people with overweight or obesity, lion’s mane supplementation reduced depression scores by about 29% and anxiety scores by roughly 34% over the study period. A separate double-blind pilot study in young adults found improvements in stress and mood measures at weeks 8, 12, and 16 of supplementation. No trial to date has reported depression as a side effect.
Animal studies reinforce these findings. In mice subjected to chronic stress, lion’s mane reversed the stress-induced drops in serotonin and dopamine in the hippocampus, two brain chemicals closely tied to mood regulation. It also reduced inflammation markers and boosted production of brain-derived neurotrophic factor (BDNF), a protein that supports the health and growth of brain cells. Low BDNF levels are a hallmark of depression, so increasing them is generally considered protective.
The Kappa Opioid Receptor Question
One plausible biological pathway gets discussed in online communities: a compound called erinacine E, found in lion’s mane mycelium, acts as an agonist at kappa opioid receptors. This matters because activating kappa opioid receptors is associated with feelings of dysphoria, reduced motivation, and anhedonia (the inability to feel pleasure). Drugs that stimulate these receptors tend to produce unpleasant mood states rather than euphoria.
There are important caveats, though. Erinacine E was isolated from a related species (Hericium ramosum), not the standard lion’s mane (Hericium erinaceus) most supplements are made from. Its binding activity was measured at a concentration of 0.8 micromolar in a lab dish, and there’s no human data showing that oral lion’s mane supplements deliver enough erinacine E to the brain to meaningfully activate these receptors. It’s a legitimate theoretical concern, not a demonstrated clinical effect.
The NGF Paradox
Lion’s mane is best known for stimulating nerve growth factor (NGF), a protein involved in maintaining and regenerating nerve cells. That sounds universally positive, but the relationship between NGF and mood is more complicated than supplement marketing suggests. A case-control study published in the Journal of International Medical Research found that people with major depressive disorder had significantly higher blood levels of NGF (about 105 pg/mL) compared to healthy controls (about 72 pg/mL).
Researchers interpret elevated NGF in depressed individuals as a stress response rather than a cause of depression. Emotional stress, anxiety, and challenging life circumstances all trigger the body to produce more NGF. So high NGF doesn’t appear to drive depression, but it does travel alongside it. Whether artificially boosting NGF through supplementation could create problems for someone already in a stressed or depressed state remains an open question. It’s worth noting that the key active compounds in lion’s mane (called hericenones, found in the fruiting body) actually failed to stimulate NGF gene expression in cell studies, suggesting they may not be the components responsible for the mushroom’s brain-related effects.
What Happens When You Stop Taking It
One pattern that could feel like lion’s mane “caused” depression is what happens after stopping it. In the young adult pilot study, the mood and cognitive improvements seen during 16 weeks of supplementation disappeared within four weeks of stopping. This isn’t a withdrawal effect in the traditional sense, where your baseline gets worse. It’s more like the benefits simply fade, and you return to where you started. But if you’ve grown accustomed to feeling better, that return to baseline can subjectively feel like a dip, especially if you’re not expecting it.
Safety Profile and Practical Considerations
From a toxicology standpoint, lion’s mane has a clean safety record. A 2025 assessment published in Frontiers in Toxicology found no acute toxicity, no subchronic oral toxicity, and no genotoxicity in rats given up to 2,000 mg per kilogram of body weight daily for 90 days. That’s an extremely high dose relative to what any human would take. The no-observed-adverse-effect level was set at the maximum dose tested, meaning researchers couldn’t find a threshold where problems began.
That said, toxicology studies measure organ damage, blood markers, and physical health outcomes. They don’t typically measure subtle mood shifts, motivation changes, or emotional blunting. The absence of toxicity is not the same as the absence of all possible mood effects in all people. Individual variation in gut bacteria, liver enzyme activity, existing brain chemistry, and the specific lion’s mane product (mycelium vs. fruiting body, extract strength, species purity) all introduce variables that clinical trials haven’t fully mapped.
If you’re taking lion’s mane and notice your mood worsening, the most practical step is to stop taking it for a few weeks and see if the change reverses. Because supplements aren’t standardized the way medications are, it’s also possible that a reaction stems from other ingredients, contaminants, or fillers in a particular product rather than the mushroom itself.