Peptifact

Peptide Side Effects: We Counted FDA's Adverse Event Database, and It Is Almost Empty

Fourteen research-market peptides produce 85 adverse event reports in FDA's database. Two approved GLP-1 drugs produce 10,733. That gap is not a safety finding — it is the absence of a reporting channel, and this page explains why that matters more.

Robert F · Edited by Caroline S · Published 2026-09-13

Illustration: A precision scale with an empty weighing pan, next to a clear glass vial on a lab bench.
Illustration

Search for the side effects of any research peptide and the results divide into two kinds: seller pages listing mild, transient effects, and warning pages listing serious ones. Neither cites a dataset, because until you go looking it is not obvious that there barely is one.

This page reports what FDA's adverse event database actually contains for these compounds, compound by compound, with the date it was queried. The result is a near-empty record, and the reason it is empty is more useful than the counts. The broader question of how safe each kind of peptide product is — approved, compounded or research-use — is answered on our peptide safety overview.

This is journalism about a public dataset. It is not medical advice, and nothing here describes what anyone should do.

What the database holds

FDA's adverse event reporting system collects reports of events that somebody associated with a drug. It is queryable through the openFDA interface. Queried on 13 September 2026 for reports naming each product:

Compound Reports
Thymosin alpha 1 37
BPC-157 18
Ipamorelin 11
Melanotan 10
CJC-1295 4
GHK-Cu 2
Semax 2
TB-500 1
Selank 0
Epitalon 0
MOTS-c 0
KPV 0
AOD-9604 0
Elamipretide 0
Total, fourteen compounds 85

Two of those counts need a footnote. One of the two Semax reports names a product coded by FDA's dictionary as the antidepressant citalopram, as our semax side-effects page explains; and AOD-9604's zero sits beside six placebo-controlled trials its developer ran, pooled on our record of AOD-9604's trial side effects.

And for comparison, in the same database on the same day:

Approved drug Reports
Semaglutide 7,580
Tirzepatide 3,153
Total, two drugs 10,733

Two approved medicines produce roughly 126 reports for every one produced by fourteen research-market peptides combined. Six of the fourteen produce none at all.

The wrong conclusion, and why it is so tempting

The obvious reading is that research peptides are much safer than GLP-1 drugs. That reading is wrong, and understanding why is the point of the page.

FDA's system is passive. It does not go looking for harm; it receives reports that someone chooses or is required to file. Three groups do the filing, and every one of them is missing from the research-peptide market:

Manufacturers. Mandatory reporting duties attach to the holder of an approved product's marketing authorisation. A seller shipping research-labelled material holds no marketing authorisation, and therefore no duty. Nobody on the supply side is obliged to collect anything.

Clinicians. A prescribed drug has a prescriber — someone who knows what the patient took, sees them afterwards, recognises an event as possibly drug-related, and knows the reporting route exists. Somebody who bought a vial online has no prescriber. If they see a doctor at all, they may not mention it.

Patients who can name the product. Filing a report requires naming what was taken. A buyer of research material frequently cannot: the vial's contents are the seller's claim, not a verified fact, which is the whole subject of our guide to reading a certificate of analysis. "I injected something sold as BPC-157" is not a product name a surveillance system can index.

So the near-zero counts are a measurement of the reporting channel, not of the compound. Absence of reports is absence of a way to report. The error runs in one direction only — the system can undercount badly and cannot overcount — which means these numbers set no upper bound on anything.

The GLP-1 comparison makes the mechanism visible rather than the risk. Those 10,733 reports are what a functioning surveillance system attached to very wide prescribed use looks like. The 85 are what no system looks like.

The most common complaint about BPC-157 is that it did not work

BPC-157 is the most-searched compound in this market. The human studies behind it and each report read individually are on our BPC-157 side effects page; by the count used here, its 18 reports break down like this:

Reaction term Reports
Drug ineffective 3
Erythema 3
Abdominal discomfort 2
Balance disorder 2
Drug intolerance 2
Dyspnoea 2
Flushing 2
Headache 2
Hypersensitivity 2
Nausea 2

The joint most frequent coded term is drug ineffective. Of the handful of people who went to the trouble of filing a formal report with a federal agency about this compound, the largest single group did so to say it had no effect.

The year distribution — 2 in 2021, 2 in 2022, 4 in 2023, none recorded in 2024, 3 in 2025, 7 in 2026 — shows counts rising, with 2026 the highest. On a base this small that most plausibly tracks growing use and growing awareness that a reporting route exists, rather than any change in the compound.

Thymosin alpha 1's record has the same character. Its top term is off label use, at 8 of 37 reports — again not a symptom, and again a fact about how the compound reaches people. Its clinical file is set out on our thymosin alpha 1 dosage page. Counted under all three of its names rather than one, it reaches 248 reports, 187 of them listing it only as a bystander drug; the recount sits with its placebo-trial data on the thymosin alpha 1 side-effects page.

What is actually known, compound by compound

Building the dosage cluster on this site meant opening the human literature for each compound in turn, and the same pattern recurred:

  • Most have no human safety data because they have almost no human studies. Epitalon returns zero registered trials; FDA's 2026 review of it found no human safety study at all (epitalon side effects); SLU-PP-332, sold as a tablet, has never been given to a person under observation; DSIP returns zero despite 407 papers; IGF-1 LR3's 44 indexed papers include not one human study, so its side-effect record has to borrow its nearest labelled relative's. 5-amino-1MQ is in the same position: its whole in vivo record is three short mouse papers from its own developers, one of which measured how little of an oral dose was absorbed. KPV has none by any route: FDA's 2026 review searched seven sources and found no human exposure at all.
  • Where human studies exist they are small and short. The longest exposure in the DSIP sleep literature is seven consecutive nights. The entire clinical experience section of the FORZINITY label — the approved elamipretide product, covered on our SS-31 dosage page — rests on twelve patients.
  • A withdrawn label is still a record. Sermorelin's pediatric programme reported flushing and injection-site pain as its most common events, and its adverse-event record, counted report by report, shows why a FAERS tally has to be opened before it is quoted.
  • Injection-site reactions are the one consistent finding. Across the compounds with any trial record, local irritation at the injection site is what gets reported. It is also the least informative possible finding, since it says nothing about systemic effects. One investigational compound shows the dose relationship plainly: in cagrilintide's phase 2 trial, injection-site redness rose from 5% at the lowest dose to 17% at the highest, against none on placebo — the arm-by-arm cagrilintide table is on its own page.
  • The approved compounds in this catalogue have real safety sections, and they are specific. The FORZINITY label carries a warning against use in neonates because of benzyl alcohol. The VYLEESI label for bremelanotide carries limitations of use excluding men. These exist because a regulator required them, and their absence elsewhere is not reassurance. Two of those labelled records are counted in full, trial table and FDA reports together, on the tesamorelin and PT-141 pages.

What FDA has said, and what it reasoned from

On 29 September 2023, FDA placed GHRP-2, GHRP-6, ipamorelin acetate and kisspeptin-10 in category 2 of its compounding lists — substances identified as presenting significant safety risks. The stated concerns centre on immunogenicity together with insufficient safety data, and for the secretagogues, endocrine effects. The whole record is indexed on our page covering FDA's category 2 list.

Immunogenicity is the risk that the body raises an immune response against an injected peptide. It matters twice over: the response can neutralise the substance, and it can cross-react with the body's own version of a similar molecule.

Note what that reasoning is not based on. There was no adverse event record to reason from — ipamorelin's eleven reports and kisspeptin's none could not support any conclusion. FDA reasoned from structure and from the absence of data, which is what a regulator does when the evidence it would normally use does not exist. Those eleven ipamorelin reports, opened one by one alongside its two surgical trials, are set out on our ipamorelin side-effect record.

It also describes exactly the kind of harm this dataset would never capture. An immune response developing over months, producing fatigue or an endocrine shift nobody connects to a vial bought two years earlier, generates no report from anyone. Two compounds in that table now have their own record read line by line: CJC-1295, where FDA's 2024 review sets out the adverse-event rates from its two small 2006 trials, and MOTS-c, where the same kind of review found no human exposure to read at all.

What this page cannot tell you

It cannot give a side-effect profile for any of these compounds, because no dataset capable of producing one exists.

It cannot tell you that a compound with zero reports is dangerous. The argument here is symmetrical: these counts support no conclusion in either direction. A zero can even sit beside a substantial clinical literature — tesofensine's trial record runs to thirteen registered studies and publishes a dose-dependent heart-rate effect at every step, and it holds no US adverse-event record at all, because it holds no US approval.

It cannot substitute for a clinician. Anyone experiencing a symptom they associate with anything they have taken needs a person who can examine them, and this is a publication.

What it can do is replace a guess with a number, and name the reason the number is unusable. A seller citing the absence of reported side effects is citing the absence of a reporting system, and now you can check that yourself.

How to check this in five minutes

The openFDA adverse event endpoint is public and needs no key. Query the drug/event.json endpoint with search=patient.drug.medicinalproduct:"BPC-157" and read meta.results.total. Swap the product name for any compound above. Add count=patient.reaction.reactionmeddrapt.exact to see the coded terms, or count=receivedate for the distribution over time.

Run it for semaglutide alongside, in the same session, and the contrast in the two totals is the entire argument on this page.

The counts are near-zero because the reporting channel is missing, not because nothing has been observed. Where a compound has actually been given to animals under measurement, adverse findings do appear — the adipotide record documents reversible kidney changes in monkeys at the dose the study identified as therapeutic, which is the kind of signal that never reaches an adverse event database for a compound sold this way.

Sources and dates

  • openFDA drug adverse event endpoint (api.fda.gov/drug/event.json), total counts by patient.drug.medicinalproduct and reaction-term and receive-date frequency counts. All queries run 13 September 2026. Product-name matching is against free-text reported product names, so counts index reports naming that string.
  • FDA, Certain Bulk Drug Substances for Use in Compounding That May Present Significant Safety Risks. Content current as of 22 April 2026; read 13 September 2026.
  • Ancell CD, Phipps J, Young L. Thymosin alpha-1. Am J Health Syst Pharm. 2001;58(10):879–85. PMID 11381492, for the injection-site tolerability finding.
  • Schneider-Helmert D. Effects of delta-sleep-inducing peptide on 24-hour sleep-wake behaviour in severe chronic insomnia. Eur Neurol. 1987;27(2):120–9. PMID 3622582, for the seven-night exposure.
  • DailyMed SPL records for FORZINITY (elamipretide) and VYLEESI (bremelanotide), for the labelled warnings and limitations cited. Previously read 11 September 2026 and 8 September 2026 respectively for this site's dosage pages.

Frequently asked questions

What are the side effects of peptides?

For most compounds sold in the research-peptide market, there is no reliable answer, and that is the honest finding rather than an evasion. FDA's adverse event database held 85 reports across fourteen of these compounds when queried on 13 September 2026, with six returning zero. There is no dataset large enough to produce a side-effect profile. What can be said is compound-specific and comes from the small clinical studies that exist — injection-site reactions are the most consistently reported finding across the few compounds with human trials, and beyond that the record thins out very quickly.

Does a low number of adverse event reports mean a peptide is safe?

No, and this is the most important thing on this page. FDA's system is passive: it collects reports that somebody files. Mandatory filing duties attach to companies holding marketing authorisations for approved drugs. A research-labelled vial has no marketing authorisation, so its seller has no duty; a buyer without a prescription has no clinician positioned to report; and someone who has not told a doctor what they injected cannot be reported on at all. A near-zero count therefore measures a missing reporting channel. Absence of reports is not absence of events.

How many adverse event reports does BPC-157 have?

Eighteen, across the whole database, when queried on 13 September 2026. They arrived across 2021, 2022, 2023, 2025 and 2026, with seven in 2026 — the highest annual count, which is consistent with rising use rather than with a new signal. The most frequently coded terms are 'drug ineffective' and erythema, three reports each, followed by abdominal discomfort, balance disorder, drug intolerance, dyspnoea, flushing, headache, hypersensitivity and nausea at two each. Eighteen reports cannot support a side-effect profile for a compound used by a large number of people.

Which peptides have the most reported side effects?

Among the compounds checked here, thymosin alpha 1 at 37 reports, then BPC-157 at 18, ipamorelin at 11 and melanotan at 10. That ordering tracks how each compound reaches people rather than how dangerous it is — thymosin alpha 1 has a clinical trial programme and clinical use behind it, which means clinicians positioned to file. Reading this list as a risk ranking would be exactly backwards: the compounds with the most reports are the ones with the most formal supervision.

Why do GLP-1 drugs have so many more reports than research peptides?

Because every part of the reporting chain exists for them and none of it exists for research peptides. Semaglutide and tirzepatide are prescribed by clinicians who can recognise and report an event, dispensed by pharmacists, and marketed by companies with statutory obligations to collect and submit reports. Their combined 10,733 reports reflect a functioning surveillance system attached to very wide use. The 85 reports across fourteen research-market compounds reflect no surveillance system at all.

Has FDA said anything about the safety of these peptides?

Yes, and the reasoning is worth noting because of what it rests on. FDA placed GHRP-2, GHRP-6, ipamorelin acetate and kisspeptin-10 in category 2 of its compounding lists on 29 September 2023, with stated concerns centring on immunogenicity — the risk that an injected peptide provokes an immune response — and insufficient safety data. That is a prospective, mechanism-level judgement reached without an event record to reason from, which is what a regulator does when the evidence it would normally use does not exist. The full record is indexed on our page covering that list.

What is immunogenicity and why does FDA keep raising it for peptides?

Immunogenicity is the risk that the body mounts an immune response against an injected protein or peptide. It matters for two reasons: the response can neutralise the substance, and it can cross-react with the body's own version of the molecule, which is the more serious possibility for peptides that resemble human hormones. It is a structural concern rather than one derived from reported events, and it is the reason a regulator can be cautious about a compound that has produced no reports at all — the harm it describes would be slow, systemic and unlikely to be recognised as drug-related by anyone who experienced it.