There are no proven peptides for depression. No peptide is approved to treat it, and none has shown a clear antidepressant effect in a good-quality human trial. The peptides with the most mood data, GLP-1 drugs like semaglutide, do not appear to raise the risk of depression or suicidal thoughts, according to an FDA review of 91 trials,[4] but they have not been shown to treat depression either.[8] Selank and Semax have only animal depression data,[10][11] and oxytocin results are small and mixed.[13]
This guide grades what exists. For related topics, see our nootropic peptides hub.
Evidence at a glance
| Peptide or treatment | Evidence level | What was shown | FDA status | Our profile |
|---|---|---|---|---|
| Psychotherapy and antidepressant medicines | FDA-approved for this use (medicines) | Standard first-line care[2][3] | Approved (not peptides) | n/a |
| Semaglutide and other GLP-1 drugs | Human RCTs | No rise in depression or suicidality; no antidepressant effect shown[4][8] | Not approved for depression | Semaglutide |
| Oxytocin (nasal) | Small human studies | More positive feelings toward baby in postpartum depression[14] | Approved only as an injection for labor and postpartum bleeding | Oxytocin |
| Selank | Animal or lab only (for depression) | Less depression-like behavior in rodents[11] | Not approved | Selank |
| Semax | Animal or lab only | Less anhedonia in stressed rats[10] | Not approved | Semax |
Start with what works
Depression is usually treated with talk therapy, antidepressant medicines or both, and brain stimulation is an option for some people when other treatments haven’t helped.[2] The American Psychological Association’s guideline reviewed psychological treatments and medicines across adolescents, adults and older adults and gives evidence-based recommendations for each age group.[3] If a first treatment doesn’t work, changing the dose, switching medicines or adding therapy often helps. An unproven peptide is not a substitute for that process.
GLP-1 drugs: reassuring safety, no proven benefit
GLP-1 drugs are peptide medicines for diabetes and weight. Reports of suicidal thoughts in 2023 led to reviews worldwide. Here is what the data now show:
- FDA review (January 2026): a meta-analysis of 91 placebo-controlled trials with 107,910 patients found no increased risk of suicidal ideation or behavior, and no increased risk of depression, anxiety, irritability or psychosis. FDA asked makers to remove the suicide warning from weight-loss GLP-1 labels.[4]
- STEP trials (2024): in 3,377 adults without major psychiatric illness, depression scores after 68 weeks were slightly lower on semaglutide 2.4 mg than placebo, and people on semaglutide were less likely to move into a more severe depression category.[5]
- Trial meta-analysis (2025): across 27 trials and about 59,000 people, suicide and self-harm events were very rare and not significantly different from placebo.[6]
- Health-record study (2024): among 240,618 people with overweight or obesity, semaglutide was linked to a lower risk of new suicidal ideation than other weight-loss drugs.[7]
But safety is not the same as treatment. In the only randomized trial in major depression, 72 adults took oral semaglutide or placebo for 16 weeks. Semaglutide did not change depression severity or how often people had suicidal thoughts, though weight fell by about 6 kg more.[8] A Danish trial of 116 people with depression and overweight is recruiting to test mood effects directly, with results expected after 2027.[9]
Read the full breakdown in GLP-1 and depression.
Selank and Semax: rodent data only for depression
Selank and Semax are Russian nasal peptides often marketed online for mood.
- Selank reduced depression-like behavior in rats bred to show it, at high repeated doses, and in mice at low single doses.[11] Its human studies, such as a 62-patient comparison with a benzodiazepine, were in generalized anxiety and neurasthenia, not depression.[12]
- Semax reduced loss of pleasure (anhedonia) and restored a brain growth factor, BDNF, in chronically stressed rats. The same study tested Melanotan II, a related peptide.[10]
No controlled human depression trial has been published for either. FDA staff recommended against allowing Semax in pharmacy compounding in 2026.[15] Compare them in Selank vs Semax.
Oxytocin: small and mixed
A 2025 review of randomized trials found that oxytocin nasal spray improved how mothers with postpartum depression perceived their infants, but its effects on mood were inconsistent. The review also described possible benefits as an add-on to standard treatment in major depression.[13] In one study of 45 mothers with postpartum depression symptoms, single doses increased positive feelings and regard for the baby but did not reduce negative mood.[14] Studies are small and short.
When GLP-1 drugs and depression overlap
Many people who take GLP-1 drugs for weight or diabetes also live with depression. The current evidence does not suggest stopping a GLP-1 drug because of depression risk, but mental health care should stay in place alongside it. FDA advises reporting new or worsening depression, suicidal thoughts or unusual mood changes to your clinician.[4] Weight loss can improve how some people feel, but it is not a treatment for depression on its own.
Safety concerns with mood peptides
- Unregulated products: Selank and Semax sold online as “research chemicals” are not checked for purity or dose.
- Regulatory status: neither is FDA-approved, and FDA lists several research peptides among compounding substances with safety concerns.[16]
- Interactions: effects alongside antidepressants have not been studied.
- Delay in care: depression can worsen without effective treatment.
Questions to ask your clinician
- Is my current treatment at the right dose, and what are my next options?
- Would adding or changing therapy help?
- If I take a GLP-1 drug, how should I report mood changes?
For related reading, see best peptides for anxiety, peptides for PTSD and Dihexa vs Semax vs Selank.
