Cognitive · Reference
PE-22-28 Side Effects: What Is Known, What Is Not, and When to Call
This page covers what is reported, what the animal safety work did and did not show, the cautions that come from PE-22-28's mechanism, when to message your care team and when to get emergency care, who should not take it, and how Pepti supplies it. The product reference is what is PE-22-28.
Treatments mentioned
PE-22-28's side effects in people are unknown, because no human trial of any kind has been run. What gets reported clinically is mostly injection-site redness, mild soreness or bruising, and occasionally a headache in the first days. The rodent work reported no pain, seizure, cardiac or ischaemia-worsening signal at the doses studied, which is reassuring as far as it goes and does not go far. Three cautions matter most: serotonergic medication, diabetes or glucose-lowering medication, and a seizure history. Any change in mood that worries you is reported promptly, and thoughts of harming yourself are an emergency: call or text 988, or call 911.
If you are in crisis or thinking about harming yourself, call or text 988 in the US, or call 911, now.
This page covers what is reported, what the animal safety work did and did not show, the cautions that come from PE-22-28's mechanism, when to message your care team and when to get emergency care, who should not take it, and how Pepti supplies it. The product reference is what is PE-22-28.
PE-22-28 Side Effects
The short answer
| Question | Answer |
|---|---|
| What are the side effects of PE-22-28? | In humans, unknown; no trials have been run |
| What is reported clinically? | Injection-site redness, mild soreness, occasional bruising; occasional headache in the first days |
| What did the animal safety work find? | No pain, seizure, cardiac or ischaemia-worsening signal at the doses that produced behavioural effects (Neuropharmacology, 2012) |
| Is there an interaction list? | No; the trials that would produce one have not been run |
| Biggest caution | Serotonergic medication: antidepressants, triptans, lithium, tramadol |
| Other cautions | Diabetes or glucose-lowering medication; a seizure history |
| Pregnancy or breastfeeding | Not used; safety data is absent |
| A worrying mood change | Contact your physician promptly; 988 or 911 if you feel unsafe |
PE-22-28 Side Effects
What people report on PE-22-28
Injection-site reactions
The commonest clinical report is at the injection site: redness, mild soreness and occasional bruising. These are the same kind of reactions any subcutaneous injection can produce. Rotating between the abdomen and thigh, and not reusing the same spot, is the usual answer. A reaction that spreads, keeps growing, or becomes hot and painful is worth a message to your care team the same day.
Headache
Some people report a headache in the first days of any new injected peptide, PE-22-28 included. A headache that persists, is severe, or comes with vision changes or confusion is reported rather than waited out.
What is not described
Nothing in the live research describes PE-22-28 producing nausea, sleepiness, stimulation, appetite change or withdrawal. That is not the same as showing they do not happen: the human studies that would find them have not been run. No withdrawal and no rebound have been described for the same reason.
Effect What the live research says What to do Injection-site redness, soreness, bruising The commonest clinical report Rotate sites; message your care team if it spreads Headache in the first days Occasional Report it if it persists or is severe Any change in mood Not a described effect; always reportable Contact your physician promptly Withdrawal or rebound after stopping Not described, because not studied Report anything unexpected Allergic reaction Not described; possible with any injection Facial or throat swelling or difficulty breathing: call 911
PE-22-28 Side Effects
What the animal safety work found
Why TREK-1 blockade raised safety questions
PE-22-28 blocks TREK-1, a background potassium channel that helps set how excitable a neuron is. TREK-1 does several jobs beyond mood: pain signalling, protection against seizures, and protection of neurons during reduced blood flow. Blocking it could, in principle, make any of those worse.
What the 2012 study tested
A 2012 paper in Neuropharmacology tested spadin, PE-22-28's longer parent fragment, in mice against exactly those endpoints. It reported no pro-pain, pro-seizure or ischaemia-worsening signal at the doses that produced the behavioural effect, and the live research also describes no cardiac signal and no toxicity in the mice and rats studied. The 2017 Frontiers in Pharmacology work that described PE-22-28 itself built on that.
What that does and does not tell you
What it shows What it does not show No pain, seizure or ischaemia signal in mice at behaviourally active doses Anything about humans No toxicity reported in the rodents studied Long-term safety, in any species A plausible reason the channel can be blocked without the feared effects Safety alongside other medications Safety in pregnancy, in people with seizures, or in people with diabetes
PE-22-28 Side Effects
Cautions that come from the mechanism
Serotonergic medication
Because the proposed mechanism runs through serotonin signalling, anyone taking an antidepressant, a triptan, lithium, tramadol or any other serotonergic drug must say so on the intake. In rodents, blocking TREK-1 on serotonergic neurons was associated with increased firing, the same direction of effect SSRIs are thought to produce by a different route. The combination has never been studied in people. Never stop or reduce a psychiatric medication on your own.
Diabetes and glucose-lowering medication
Cell work described the parent peptide increasing insulin secretion from pancreatic beta cells (Journal of Diabetes Research, 2016). Nobody has measured that in people, but anyone with diabetes, or on insulin or other glucose-lowering medication, should raise it. Shakiness, sweating and confusion can be low blood sugar: treat it, then report it.
A seizure history
TREK-1 is involved in seizure protection. The rodent work found no problem, but anyone with a seizure history should discuss it rather than assume.
A diagnosed mood disorder
PE-22-28 is not a treatment for depression or for any mood disorder. If you are under treatment, the clinician managing it needs to be part of the decision. Bipolar disorder and psychosis have no safety data with any mood-active compound and need the treating psychiatrist involved.
PE-22-28 Side Effects
When to message your care team, and when to get help now
| What happens | What to do |
|---|---|
| Redness or soreness at the site that settles | Rotate sites; mention it at your refill |
| A reaction that spreads, grows, or becomes hot and painful | Message your care team the same day |
| A headache that persists | Message your care team |
| Shakiness, sweating, confusion, if you have diabetes | Treat low blood sugar, then report it |
| A change in mood, agitation or sleep that worries you or those around you | Contact your physician promptly |
| Thoughts of harming yourself | Call or text 988, or call 911, now |
| Facial or throat swelling, widespread rash, difficulty breathing, a seizure | Call 911 first, then tell your physician |
| You think you may have taken too much | Call Poison Control at 1-800-222-1222 and message your care team |
Do not skip, double or change a dose to compensate for anything. Your care team is reachable through your account.
PE-22-28 Side Effects
Who should not take PE-22-28, or should discuss it first
| Situation | Why |
|---|---|
| Pregnancy or breastfeeding | Not used; safety data is absent |
| Serotonergic medication | The combination has never been studied in people |
| Bipolar disorder or psychosis | No safety data; the treating psychiatrist should be involved |
| Diabetes or glucose-lowering medication | Cell work on insulin secretion; raise it |
| A seizure history | TREK-1 is involved in seizure protection |
| Under 18 | Not prescribed |
| Tested athletes | Not named on the 2026 WADA list, but the S0 non-approved substances section can apply |
PE-22-28 Side Effects
What the evidence shows, honestly
There are no randomised controlled trials of PE-22-28 in humans, and no published human trials of any kind. The safety picture is rodent work plus clinical reports, mostly injection-site. That is thinner than the side-effect record for most compounded peptides, and far thinner than for any approved antidepressant, which has decades of trials and a known interaction list. The only human data in the area is observational measurement of the body's own sortilin propeptide in blood (Journal of Affective Disorders, 2017; a 2018 paper after electroconvulsive therapy), which is not a study of giving PE-22-28 to anyone.
PE-22-28 has not been evaluated by the FDA at all. It is not in Category 1, 2 or 3 of the 503A nominated-substances list updated 14 May 2026, does not appear on the FDA's significant-safety-risk page, and was not on the July 2026 Pharmacy Compounding Advisory Committee agenda. No safety notice, no vote either way. Compounded medications are not FDA approved. Side effects across the wider category are in peptide side effects: what to watch for.
PE-22-28 Side Effects
How Pepti supplies PE-22-28
| Item | Detail |
|---|---|
| Product | PE-22-28 (Injectable) |
| Vial | 5 mL multi-dose vial, 10 mg PE-22-28 at 2 mg/mL |
| Typical printed directions | Inject 0.25 mL (25 units) subcutaneously once daily Monday through Friday |
| Amount per typical dose | 0.5 mg (math only) |
| Doses per vial | 20, about four weeks |
| Price | $219 a month all-in |
Every price is all-in, covering medication, physician review, refill management and shipping, with no membership fee. Pepti is cash-pay and does not bill insurance. Vials arrive as ready-to-use multi-dose solutions with sterile syringes and alcohol prep pads, shipped refrigerated with ice packs. Refills run every 28 days, one vial per fill. Your physician sets your directions after reviewing your intake, and they are printed on the vial. The arithmetic is in PE-22-28 dosage.
PE-22-28 Side Effects
Where to get PE-22-28 prescribed
Research-use-only PE-22-28 has no pharmacy accountable for identity, purity, sterility or concentration, and nobody reviewing your medications. The prescription route:
- Complete a free online intake covering your history, every medication you take, any mood diagnosis, diabetes, seizures, pregnancy and breastfeeding status.
- A physician licensed in your state reviews it, usually within 24 hours.
- If it is appropriate, a PCAB-accredited, FDA-registered US 503A compounding pharmacy prepares it to that prescription. Lot test results are published at /quality/lab-results.
- It ships refrigerated with your directions printed on the vial.
- Your care team stays reachable for side effects and mood changes.
Step by step: how to get PE-22-28 prescribed online. Bloodwork is not required for any Pepti treatment. If your physician wants labs for your care, they'll ask through your account.
References
What this is based on.
References
- Djillani A, Pietri M, Moreno S et al.. Shortened Spadin Analogs Display Better TREK-1 Inhibition, In Vivo Stability and Antidepressant Activity · Front Pharmacol (2017) · PMID 28955242
- Mazella J, Pétrault O, Lucas G et al.. Spadin, a sortilin-derived peptide, targeting rodent TREK-1 channels: a new concept in the antidepressant drug design · PLoS Biol (2010) · PMID 20405001
- Heurteaux C, Lucas G, Guy N et al.. Deletion of the background potassium channel TREK-1 results in a depression-resistant phenotype · Nat Neurosci (2006) · PMID 16906152
- Moha Ou Maati H, Veyssiere J, Labbal F et al.. Spadin as a new antidepressant: absence of TREK-1-related side effects · Neuropharmacology (2012) · PMID 21807005
- Devader C, Khayachi A, Veyssière J et al.. In vitro and in vivo regulation of synaptogenesis by the novel antidepressant spadin · Br J Pharmacol (2015) · PMID 25598009
- Moha ou Maati H, Bourcier-Lucas C, Veyssiere J et al.. The peptidic antidepressant spadin interacts with prefrontal 5-HT(4) and mGluR(2) receptors in the control of serotonergic function · Brain Struct Funct (2016) · PMID 25233810
- Ye D, Li Y, Zhang X et al.. TREK1 channel blockade induces an antidepressant-like response synergizing with 5-HT1A receptor signaling · Eur Neuropsychopharmacol (2015) · PMID 26441141
- Hivelin C, Béraud-Dufour S, Devader C et al.. Potentiation of Calcium Influx and Insulin Secretion in Pancreatic Beta Cell by the Specific TREK-1 Blocker Spadin · J Diabetes Res (2016) · PMID 28105440
- Devader C, Roulot M, Moréno S et al.. Serum sortilin-derived propeptides concentrations are decreased in major depressive disorder patients · J Affect Disord (2017) · PMID 27838145
- Roulot M, Minelli A, Bortolomasi M et al.. Increased serum levels of sortilin-derived propeptide after electroconvulsive therapy in treatment-resistant depressed patients · Neuropsychiatr Dis Treat (2018) · PMID 30233189
- Qi X, Xu H, Wang L et al.. Comparison of Therapeutic Effects of TREK1 Blockers and Fluoxetine on Chronic Unpredicted Mild Stress Sensitive Rats · ACS Chem Neurosci (2018) · PMID 29952548
- Djillani A, Pietri M, Mazella J et al.. Fighting against depression with TREK-1 blockers: Past and future. A focus on spadin · Pharmacol Ther (2019) · PMID 30291907
Citations are provided for educational purposes. They do not constitute medical advice. Always discuss any peptide protocol with your prescribing physician.
Common questions
PE-22-28 Side Effects, answered.
In humans, unknown, because no trials have been run. Clinically, the commonest reports are injection-site redness, mild soreness or bruising, and occasionally a headache in the first days.
There is no human safety data. Rodent work reported no pain, seizure, cardiac or ischaemia-worsening signal at the doses studied, and no toxicity. That is reassuring as far as it goes, and it says nothing about long-term use or use alongside other medications.
Neither is a described effect, but PE-22-28 is proposed to act on mood pathways, so any mood change that worries you or those around you goes to your physician promptly. Thoughts of self-harm are an emergency: 988 or 911.
Only if the physician who prescribes both says so. The proposed mechanism overlaps with serotonin signalling and the combination has never been studied in people. Never stop an antidepressant on your own.
Some people report a headache in the first days of a new injected peptide. Report one that persists or is severe.
Cell work described the parent peptide increasing insulin secretion from pancreatic beta cells. It has not been measured in people. If you have diabetes or take glucose-lowering medication, raise it on your intake.
Discuss it first. TREK-1 is involved in seizure protection; the rodent work found no problem, but that is not human data.
None has been described, but only because the human studies that would find them have not been run. Report anything unexpected after stopping.
Call Poison Control at 1-800-222-1222 and message your care team. Do not skip or change your next dose to compensate.
No. It is not used in pregnancy or while breastfeeding, where safety data is absent.
No. Bloodwork is not required for any Pepti treatment. If your physician wants labs for your care, they'll ask through your account. The free assessment goes to a physician licensed in your state. A consultation does not guarantee a prescription.
Next step
See what a physician recommends for you.
A licensed physician in your state reviews your intake and decides what is appropriate. A consultation does not guarantee a prescription.