Depression and anxiety are not one disease. They are different bottlenecks that can look the same on the outside. Low serotonin, low dopamine, high inflammation, high glutamate, low energy, and a gut that talks to the brain in the wrong way. That is why a drug that works for one person does nothing for another, and why experimental ideas keep coming back to the same few mechanisms, just with a new compound.

Off label here means a compound was studied or sold for one thing, and people are now using it for mood because of how it works in the body. That is a theory. A theory is not a trial. I will say which part is mechanism, which part is animal data, and which part is an actual human trial, for each one. If the human trial is small or missing, I will say so. I am not telling you to take these.

NAC, N-acetyl cysteine, was first a mucolytic and a paracetamol overdose antidote. Off label, people use it for mood because cysteine is the rate limiting building block for glutathione, the brain's main antioxidant, and because NAC modulates glutamate through the cystine glutamate antiporter. In plain terms, it helps the brain clear oxidative noise and calm excess glutamate signalling. Glutamate is the main excitatory transmitter, and too much of it is linked to depression, anxiety, and obsessive thoughts. Human trials are moderate, usually 600 to 1,800 mg a day in divided doses for 2 to 4 weeks, with the best signal when oxidative stress or toxin exposure is involved. It can upset the stomach, it smells like sulfur, and it interacts with nitroglycerin and some blood pressure drugs. It is not a daily focus pill, and it is not a substitute for an antidepressant.

Creatine is the energy one. It maintains a reserve of phosphocreatine, which donates a phosphate group to spent ATP to regenerate it almost instantly. The brain uses the same system, which is why researchers tested it when people were sleep deprived or mentally worn out. A 2024 meta analysis of 16 trials, 492 people, found creatine improved memory and processing speed, with no clear effect on overall cognition. For depression, a small trial found creatine as an add on to an SSRI helped women with major depression, with the effect strongest in those who started low. The dose is 3 to 5 g of creatine monohydrate a day for weeks. Brain creatine rises much less than muscle creatine, about 9 to 11 percent versus about 20 percent, which is why brain studies use more and wait longer. If you eat meat and sleep well, expect a small effect. If you are vegetarian, older, or short on sleep, you are more likely to notice it. Creatine helps you cope with bad sleep. It does not replace sleep, and it can interact with kidney issues.

Curcumin is the inflammation one. It is anti inflammatory and antioxidant in lab studies, but it barely gets absorbed. Regular turmeric powder will not do the same thing as a bioavailable form. A 2023 meta analysis found curcumin reduced depressive symptoms, with the effect strongest in people with raised inflammatory markers such as C-reactive protein. That fits the theory. Depression is not always inflammation, but a subset of people have high CRP, and that subset is the one most likely to respond to anti inflammatory ideas. If your fog and low mood follow a viral illness or track with high hs-CRP, curcumin is more plausible. If your inflammation markers are normal, expect less. It can interact with blood thinners and diabetes medicine, so check first.

Probiotics are the gut brain one. Your gut makes about 90 percent of your body's serotonin, though most of that serotonin acts locally in the gut, not in the brain. The gut talks to the brain through the vagus nerve, through immune signals, and through short chain fatty acids made by gut bacteria. A 2021 meta analysis found probiotics reduced depressive symptoms when used alongside antidepressants, but not reliably as stand alone support. That is the right framing. Probiotics are an add on, not a treatment, and the strain matters. Lactobacillus and Bifidobacterium strains are the ones most studied, but a product with a different strain, or a different dose, is not the same thing. Do not buy a generic probiotic and expect a mood effect. If you have IBS, bloating, or antibiotic use in the past year, a probiotic trial for 8 weeks is more plausible than if your gut is fine.

Inositol is the one people ask about for anxiety and OCD. It is a sugar alcohol involved in second messenger signalling, the way serotonin and other neurotransmitters talk inside the cell. In small trials, inositol at 12 to 18 g a day helped panic disorder and OCD in some people, with a dose that is high and can cause stomach upset. The trials are small, old, and not replicated in large groups. I would put it in the maybe pile if you have panic attacks and have not responded to an SSRI, and only with a clinician, because high dose inositol can interact with lithium and diabetes medicine.

Ketamine and esketamine are the rapid acting ones, and they are prescription drugs, not supplements. Ketamine is an anaesthetic that, in low doses, can rapidly reduce severe depression symptoms, largely through glutamatergic plasticity pathways, blocking NMDA receptors and then triggering a surge in brain derived neurotrophic factor, BDNF, which helps synapses grow. Esketamine, a related nasal spray medication, is FDA approved for treatment resistant depression and is being studied in bipolar depression. It must be administered in a medical setting, because of sedation, dissociation, blood pressure and misuse risks. It is not a take home nasal antidepressant. Benefit can be rapid but may fade, and repeated treatment evidence and access vary. Ketamine is approved by Health Canada as an anaesthetic. Use for depression, anxiety, and chronic pain is off label. Off label prescribing is legal in Canada when supported by clinical evidence, but it needs a specialist, a mood stabiliser if you have bipolar disorder, and monitoring for bladder issues, blood pressure, and misuse. Do not buy ketamine online, and do not take it at home.

Psilocybin is the investigational one. It is a classic psychedelic, studied in trials for depression, with a 2021 trial in the New England Journal of Medicine comparing psilocybin to escitalopram, and a 2022 trial of a single 25 mg dose in treatment resistant depression. Trials suggest potential in selected depression and serious illness distress, with partial response rates, not universal. Risks include acute fear, blood pressure effects, prolonged psychological difficulty, and destabilisation in people vulnerable to psychosis or mania. Psilocybin and MDMA are accessed only through Health Canada's Special Access Program, for serious or life threatening conditions when conventional treatments have failed. They are controlled substances. Bipolar disorder, pregnancy, and a personal or first degree family history of primary psychotic disorder are standard exclusion criteria across virtually every published psychedelic assisted therapy trial. This is not a DIY treatment. It is a research setting, with screening, preparation, and integration therapy.

Low dose lithium is another off label idea, and it needs a clear boundary. Lithium is a mood stabiliser at prescription doses, with a narrow safety window and blood monitoring. Low dose lithium, at 5 to 20 mg of elemental lithium, is sold as a supplement in some places, on the theory that lithium inhibits GSK-3 beta, a kinase involved in mood, inflammation, and neuroprotection. The human data for low dose lithium as a supplement is thin, and the risks, kidney, thyroid, and interaction with diuretics and NSAIDs, are real even at low doses. I would not take lithium orotate as a supplement without a clinician, blood monitoring, and a discussion about kidney and thyroid function. First principles does not make a risky compound safe.

Methylene blue is the one I am leaving out on purpose, even though people ask about it. It can interact dangerously with SSRIs and cause serotonin syndrome, and the human mood trials are few and small, with a 1987 trial of 15 people for bipolar depression and a 3 week trial from the same era. It also turns urine blue and can cause haemolysis in people with G6PD deficiency. Do not take it for mood.

How would I use all of this, if you were already on treatment and still felt low? I would pick one bottleneck, not five supplements at once. If your depression tracks with high CRP, try curcumin or EPA omega-3 first, and check CRP before and after. If your depression tracks with low energy and poor sleep, try creatine first, and fix sleep. If your depression tracks with gut issues, try a probiotic for 8 weeks, with one strain, not a blend of ten. If your depression is severe, treatment resistant, and you have not responded to two antidepressants, ask your psychiatrist about ketamine or esketamine in a supervised setting, not about a supplement. Give each supplement 8 to 12 weeks, except acute ones which you judge in hours. Stop what does not move one metric, like PHQ-9 each week, or GAD-7 each week. Keep what does, and check interactions before you add the next one.

A protocol is not a longer list. It is a shorter list, in the right order, with the interactions checked first.

This is education, not medical advice. It is not a diagnosis, and it does not replace professional care. Experimental and off label use, especially for ketamine, psilocybin, low dose lithium, and any serotonergic stack, needs a clinician conversation first, especially if you take prescription medicine, are pregnant, or have kidney, liver, thyroid, or heart issues.

Sources: Liao and colleagues, Translational Psychiatry, 2019, PMID 31383846. Papakostas and colleagues, American Journal of Psychiatry, 2012. Xu and colleagues, Frontiers in Nutrition, 2024. Carhart-Harris and colleagues, New England Journal of Medicine, 2021. Goodwin and colleagues, New England Journal of Medicine, 2022.