How to use this page
Every compound page on this site has a section on the side effects reported in its studies or on its label. This page links all 52 of them, grouped by the kind of evidence behind them, and adds the general adverse-event information that cuts across compounds and has a primary source.
It does not add anything a label or a trial did not say. Where a compound has no human safety data, the table says so, because "no reported side effects" and "no data" are different things and the research-peptide market tends to blur them.
For what to do about a side effect, and the warning signs that need a doctor now, see side effect management.
Three patterns that cut across compounds
Injection-site reactions
Anything injected under the skin can cause redness, pain, itching or a small lump at the site. The approved injectables document this plainly: the Forzinity (SS-31) trial recorded a local reaction in every treated patient, and injection-site reactions appear in the labels of Wegovy, Zepbound, Egrifta and Vyleesi. The 2016 FITTER injection technique recommendations identify the longer-term version, lipohypertrophy, a rubbery build-up of fat at over-used sites that also distorts absorption, and recommend site rotation and single-use needles to prevent it. See insulin syringe sizes and subcutaneous vs intramuscular.
Immunogenicity and impurities
The US FDA's compounding safety-risk list states a general concern for peptides: compounded products may pose an immunogenicity risk for certain routes because of aggregation and peptide-related impurities. It applies that reasoning, entry by entry, to BPC-157, thymosin beta-4 fragment (TB-500), CJC-1295, ipamorelin, GHRP-2, GHRP-6, kisspeptin-10, MOTS-c, epitalon, GHK-Cu, Semax, Selank, thymosin alpha-1, AOD-9604 and melanotan II. The concern is about the category of unregulated injectable peptide, not one product, and no research vial's label can settle it; see how to read a peptide vial label.
Class effects
Compounds that share a mechanism share a side-effect pattern. The GLP-1 medicines share gastrointestinal effects and the boxed thyroid warning. The GH secretagogues share raised IGF-1 and its downstream concerns. The melanocortins share nausea, flushing and pigmentation. Each is covered below.
GLP-1 and metabolic compounds
The best-documented group on the site. In the Wegovy label the most common adverse reactions were nausea (44% vs 16% on placebo), diarrhoea (30% vs 16%) and vomiting (25% vs 6%). In the STEP 8 head-to-head, gastrointestinal events were reported by 84.1% on semaglutide and 82.7% on liraglutide. All GLP-1 labels carry the boxed warning on thyroid C-cell tumours seen in rodents, with a contraindication for personal or family history of medullary thyroid carcinoma or MEN 2, and warnings on pancreatitis and gallbladder disease.
| Compound | Evidence | What the safety section covers |
|---|---|---|
| Semaglutide | Approved | Label rates, STEP 1 and SELECT discontinuations, boxed warning |
| Tirzepatide | Approved | SURMOUNT-1 discontinuation by dose, Zepbound label list |
| Liraglutide | Approved | Label list, SCALE serious events, Saxenda discontinuation |
| Orforglipron | Approved | ATTAIN-1 GI rates by dose, contraceptive warning |
| Mazdutide | Approved (China) | GLORY-1 discontinuation rates |
| Retatrutide | Phase 3 | GI events, TRIUMPH-4 dysesthesia 20.9% vs 0.7% |
| CagriSema | Phase 3 | REDEFINE 1 GI 79.6% vs 39.9%, nausea, constipation, vomiting |
| Cagrilintide | Phase 3 | Phase 2 GI rates, REDEFINE 1 figures |
| Survodutide | Phase 3 | SYNCHRONIZE-1 GI 80.9% to 89.7% vs 47.9% |
| AOD-9604 | Human pilot | Events at placebo rates in six trials; no IGF-1 change |
| 5-Amino-1MQ | Preclinical | No human safety data |
Growth hormone axis
The class concern is IGF-1. Any compound that raises GH raises IGF-1, and the theoretical long-term issues are those of growth hormone itself: fluid retention, joint aches, reduced insulin sensitivity, and the open question of IGF-1 and cancer. The clearest human data belong to MK-677's two-year trial, which recorded higher fasting glucose, lower insulin sensitivity, raised cortisol, appetite and leg swelling, and to the tesamorelin label, whose most common reactions were joint pain, injection-site redness and itching, limb pain, leg and foot swelling and muscle pain, with warnings on IGF-1 elevation, fluid retention and glucose intolerance. Ghrelin-receptor peptides add appetite and, for the older GHRPs, prolactin and cortisol.
| Compound | Evidence | What the safety section covers |
|---|---|---|
| Tesamorelin | Approved | Label reactions above 5%, glucose and IGF-1 warnings |
| GHRP-2 | Approved (diagnostic, Japan) | No side effects in the paediatric study; class hunger, prolactin, cortisol |
| Sermorelin | Formerly approved | Injection-site reactions, flushing, headache, dizziness |
| MK-677 | Human trials | Appetite, oedema, glucose, cortisol, heart failure signal in hip fracture |
| Ipamorelin | Human pilot | Tolerated in two small studies; FDA 2024 concerns |
| GHRP-6 | Human pilot | Prolactin and cortisol at top dose; stroke trial events |
| CJC-1295 with DAC | Human pilot | No serious reactions in 2006 trials; FDA heart rate and vasodilation note |
| CJC-1295 no DAC | Preclinical | No human data; borrows the DAC and FDA picture |
| IGF-1 LR3 | Preclinical | No human data; theoretical risks from IGF-1 biology |
| CJC-1295 + Ipamorelin | Untested blend | No combination data; each component's FDA concerns |
Tissue repair and blends
None of these has a controlled human trial, so none has a human adverse-event profile. The safety sections describe animal tolerability and the FDA's category concern about immunogenicity and impurities. The blends inherit every component's gaps.
| Compound | Evidence | What the safety section covers |
|---|---|---|
| BPC-157 | Preclinical | Rodent tolerability only; no human adverse-event data |
| TB-500 | Preclinical | Full-length protein's trial record; fragment untested; FDA note |
| GHK-Cu injectable | Preclinical | No injection trials; FDA compounding listing |
| GLOW | Untested blend | No blend data; all three components on the FDA list |
| KLOW | Untested blend | No blend data; all four components on the FDA list |
Immune and anti-inflammatory
| Compound | Evidence | What the safety section covers |
|---|---|---|
| Thymosin alpha-1 | Approved (abroad) | Described as well tolerated where registered; injection-site reactions |
| LL-37 | Human pilot | Topical trial with monitoring; no public label |
| ARA-290 | Human pilot | Generally well tolerated in trials; no rate stated |
| KPV | Preclinical | No human data |
Sexual health and melanocortins
The Vyleesi (PT-141) label is the reference: nausea in 40.0% of treated women versus 1.3% on placebo, plus flushing, injection-site reactions, headache and vomiting, a transient rise in blood pressure after each dose, and focal hyperpigmentation with frequent dosing. The FDA's compounding list summarises melanotan II's case literature as including melanoma, posterior reversible encephalopathy syndrome, sympathomimetic toxicity and priapism.
| Compound | Evidence | What the safety section covers |
|---|---|---|
| PT-141 | Approved | Pooled phase 3 label table, blood pressure, pigmentation |
| Melanotan I | Approved (afamelanotide) | Scenesse label table; mole darkening |
| Melanotan II | Human pilot | FDA case summary, mole changes, regulator warnings |
| Kisspeptin | Human pilot | No side effects in small trials; FDA 2023 listing |
Hormonal and fertility
These are prescription medicines with full labels. Prescribing belongs with a licensed Philippine physician.
| Compound | Evidence | What the safety section covers |
|---|---|---|
| hCG | Approved | Novarel and Pregnyl label list; ovarian hyperstimulation warnings |
| Gonadorelin | Formerly approved | Factrel and Lutrepulse label reactions |
Cognitive and mood
| Compound | Evidence | What the safety section covers |
|---|---|---|
| Cerebrolysin | Approved (PH registered) | Cochrane signal of more non-fatal serious adverse events |
| Semax | Approved (Russia) | Described as tolerated; no counts in abstracts; FDA listing |
| Selank | Approved (Russia) | No sedation reported; no counts; FDA listing |
| Pinealon | Human pilot | No safety detail; no phase 1 study |
| Dihexa | Preclinical | No human or long-term animal data; c-Met cancer concern |
Sleep, longevity and mitochondrial
| Compound | Evidence | What the safety section covers |
|---|---|---|
| SS-31 | Approved | Injection-site reactions in 100% of treated patients; allergy warning |
| NAD+ | Human pilot | Infusion gut symptoms, fast heart rate, chest pressure |
| DSIP | Human pilot | No serious events in small 1980s trials; no long-term data |
| Epitalon | Human pilot | No side effects reported by one group; telomerase and cancer concern |
| MOTS-c | Preclinical | Analogue's injection-site reactions only |
| SLU-PP-332 | Preclinical | No human data |
Muscle and myostatin
| Compound | Evidence | What the safety section covers |
|---|---|---|
| ACE-031 | Human pilot | Nosebleeds, gum bleeding, telangiectasias that halted the Duchenne trial |
| Follistatin-344 | Human pilot | Gene therapy data only; no injected-protein safety data |
Skin and cosmetic
| Compound | Evidence | What the safety section covers |
|---|---|---|
| GHK-Cu topical | Human pilot | Decades of cosmetic use; mild local irritation |
| Argireline | Human pilot | No significant adverse effects across ten trials |
| SNAP-8 | Preclinical | No SNAP-8-specific safety data |
What the pattern shows
Read down the tables and the shape of the market is visible. The compounds with proper adverse-event rates are the approved medicines, and their rates are not small: 44% nausea on Wegovy, 40% on Vyleesi, a local reaction in every patient on Forzinity. The research peptides mostly report either "well tolerated" from a study too small to detect anything, or nothing at all. The absence of a listed side effect for a research peptide is a measure of how little it has been studied, not of how safe it is.
Bloodwork is the one tool that turns some of these theoretical concerns into numbers: IGF-1 and glucose for the GH axis, HbA1c for anything metabolic, and the markers each compound's trials tracked. See bloodwork in the Philippines.
