PE-22-28 side effects and risks

Reported side effects

• Tiredness or excess sleep: User reports include tiredness after 400 mcg twice in a day; no reliable rate., moderate. Avoid driving if drowsy; seek review if symptoms persist. (source)
• Irritability, restless sleep or overstimulation: One 300 mcg injection report and one 200 400 mcg/day nasal report; no reliable rate., moderate. Stop PE-22-28 and seek review for persistent or worsening symptoms. (source)
• Nausea and poor concentration with phenelzine: One self report after 800 mcg intranasally; serotonin syndrome was not clinically confirmed., moderate. Stop the unapproved peptide and seek assessment; do not self-adjust prescribed antidepressants. (source)
• Worse mood or no improvement: A commenter reported feeling worse after about 3 weeks of 500 mcg injections. Frequency is unknown., moderate. Seek mental-health review; use urgent care for suicidal thoughts or inability to stay safe. (source)
• Allergy or infection from an unregulated product: General peptide product risks; PE 22 28 specific rates are unknown., serious. Seek immediate care for breathing problems; prompt care for spreading redness or fever. (source)

Stop and get help if

• Suicidal thoughts, a suicide plan, or inability to stay safe: Get urgent crisis help. In the US call 988; call 911 for immediate danger. Elsewhere use local emergency services.
• Confusion or agitation with fever, sweating, tremor or muscle jerks: Seek emergency care, especially with antidepressants or MAO inhibitors. PE-22-28-related serotonin toxicity is unproven.
• Trouble breathing, throat or tongue swelling, or collapse: Stop exposure and call emergency services now. Use prescribed emergency adrenaline if available.
• Spreading hot, painful redness or fever after an injection: Stop injections and seek prompt medical assessment for possible infection.

Who should avoid it

• pregnant: Precaution: fetal and pregnancy safety have not been studied in humans.
• breastfeeding: Precaution: transfer into milk and effects on a nursing infant are unknown.
• tryingToConceive: Precaution: human fertility and reproductive safety data are absent.
• under18: Precaution: no pediatric dosing or developmental safety evidence was found.
• depressionOrSuicidalThoughts: No human antidepressant trial supports replacing established care. New suicidal thoughts need urgent assessment.
• psychiatricCondition: Mood worsening and overstimulation appear in user reports. Psychiatric effects and drug interactions are unstudied.
• heartCondition: Precaution: TREK-1 has heart functions. A negative cell hERG test does not establish cardiac safety in people.
• seizureDisorder: Precaution: TREK-1 affects brain excitability. Human seizure risk is unknown.
• kidneyDisease: Precaution: human clearance and dose adjustment in kidney disease are unknown.
• liverDisease: Precaution: human metabolism and dose adjustment in liver disease are unknown.
• testedAthlete: The 2026 S0 rule covers unapproved pharmacological substances at all times.
• other: Avoid re-exposure after a serious allergic reaction to the product or its ingredients.

Interactions

• MAO inhibitors: No interaction trial. One phenelzine user reported nausea and poor concentration during PE-22-28 escalation; toxicity was not confirmed.
• SSRIs, SNRIs and other serotonin-active drugs: Possible additive brain effects are untested. Parent spadin increases serotonin-neuron firing in mice; a different mechanism does not prove compatibility.
• Insulin and sulfonylureas: Theoretical interaction: mini-spadin affects insulin-making cells in vitro. Human blood-sugar effects and low-sugar risk are unknown.
• Other brain-active peptides: Combinations are reported online without interaction or safety trials. Duplicate spadin analogues may also have different identities.

Product quality risks

• No peer-reviewed market-testing study of PE-22-28 products was found.
• General peptide warnings describe wrong amounts, unknown ingredients, microbes and endotoxin. PE-22-28-specific rates are unknown.
• A study of three online semaglutide samples found 28.56%-38.69% excess content and endotoxin in one. These are not PE-22-28 measurements.