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SLU-PP-915 Side Effects: What the Evidence Actually Shows

SLU-PP-915 side effects — what the evidence actually shows

Written by Marcus Reinhardt · Lead Analyst, Peptide Insider · LinkedIn

Evidence-first peptide coverage — every claim on this page is linked to its primary source and reviewed against our editorial policy

Citations verified against PubMed · Published: 2026-09-04 · Last updated: 2026-09-07

SLU-PP-915 side effects have never been measured in a human being — not in a trial, not in a case report, not once. This orally active pan-ERR agonist, marketed as an “exercise in a pill,” has a genuinely interesting preclinical story and a completely empty human safety file. That is the same honest bind as our other no-human-data compounds: most “SLU-PP-915 side effects” articles fill the vacuum with the language of a finished drug. We won’t. Here is what the five published papers actually measured — in mice, in cells, and in test tubes of human liver enzymes — and why none of it adds up to a side-effect profile for a person.

Quick Answer: What the SLU-PP-915 Side-Effect Data Actually Shows

There is no published human safety data for SLU-PP-915. No clinical trial, no adverse-event table, no case series — the literature is five preclinical papers: the compound’s identification (PMID 37421886), its oral exercise-capacity study in mice (PMID 41421047), two metabolic studies of its predecessor SLU-PP-332 (PMID 37739806, PMID 36988910), and an in-vitro human-liver metabolism study (PMID 41588687). Any article quoting side-effect percentages for SLU-PP-915 is citing something the research does not contain. Self-reported experiences from Reddit, all of them about the parent compound SLU-PP-332, are summarized further down; they are anecdotes, not data.

★The Documented Experience: Zero Monitored Humans

For our cagrilintide and eloralintide side-effect pages, this box summarizes what thousands of monitored trial participants went through. For SLU-PP-915, the honest version is different: no human being has ever taken SLU-PP-915 under study conditions where side effects were recorded. The closest thing to a human “exposure” in the entire literature is human liver enzymes in a test tube, used to predict how the molecule would break down — not a person, and not a side effect.

People do buy SLU-PP-915 — it sells briskly on the strength of “exercise in a pill” headlines. Those experiences exist; they have simply never been collected, controlled, or published. That is not a footnote. It is the entire human safety picture, and it is blank.

When we publish an individual account here, it will be a real person, named with permission — like the reader experiences we reference in our peptides-for-energy guide. We don’t write fiction into this slot.

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In This Guide

What Is SLU-PP-915?

SLU-PP-915 is a small molecule — not a peptide, despite its peptide-market home — developed at Saint Louis University as a pan-agonist of the estrogen-related receptors ERRα, ERRβ, and ERRγ (PMID 37421886). Chemically it is a 2,5-disubstituted thiophene carrying a boronic acid group. Its selling point is being the orally bioavailable successor to SLU-PP-332, the injection-only ERR agonist that started the “exercise mimetic” story (PMID 41421047). Like the NNMT inhibitor 5-Amino-1MQ, it pairs a compelling preclinical narrative with no clinical file at all. This page covers the safety question — which, for SLU-PP-915, means covering an absence honestly.

How It’s Thought to Work

The estrogen-related receptors are orphan nuclear receptors that regulate genes for mitochondrial biogenesis, oxidative phosphorylation, fatty acid oxidation, and the Krebs cycle, and are essential for skeletal muscle’s adaptation to aerobic exercise (PMID 41421047). SLU-PP-915 turns those receptors on. In gene-expression assays it upregulated ERR target genes including PGC-1α, lactate dehydrogenase A, DNA damage-inducible transcript 4 (Ddit4), and pyruvate dehydrogenase kinase 4, both in vitro and in vivo (PMID 37421886). The idea is that switching on the muscle’s exercise-adaptation program pharmacologically reproduces some of what training does. Mechanistic plausibility is real. But note what a mechanism is not: it is not a safety profile. ERRs sit at the control panel of mitochondrial and metabolic gene expression across tissues — turning them on system-wide can do things nobody ordered, none of it checked in a person.

KEY TAKEAWAY

SLU-PP-915 has a coherent mechanism — oral pan-ERR activation that switches on the muscle’s aerobic-exercise gene program — and a stack of supportive mouse and cell studies. That is the complete file. Every side-effect rate you have seen attached to this compound was generated somewhere other than SLU-PP-915 research on humans, because that research does not exist.

The Entire Evidence Base: Five Preclinical Papers

The literature worth knowing in full, because it is all of it. The compound was introduced in 2023 (PMID 37421886, Eur J Med Chem): a medicinal-chemistry paper identifying SLU-PP-915 (labeled compound 10s) as a potent pan-ERR agonist whose boronic acid moiety improved metabolic stability in microsomal in-vitro assays. The 2026 study (PMID 41421047, J Pharmacol Exp Ther) is the one cited for “it works orally”: in mice, 915 enhanced aerobic exercise performance — distance and duration — comparably to the injected predecessor when given intraperitoneally, and held comparable efficacy orally after adjusting for systemic exposure.

Two of the five papers are not about SLU-PP-915 at all — they are the predecessor SLU-PP-332’s metabolic file, which the newer compound leans on. In 2023 (PMID 36988910, ACS Chem Biol), SLU-PP-332 increased mitochondrial function in a muscle cell line and, in mice, increased type IIa oxidative muscle fibers and enhanced endurance through an ERRα-dependent program. In 2024 (PMID 37739806, J Pharmacol Exp Ther), it reduced fat mass, increased energy expenditure and fatty acid oxidation, and improved insulin sensitivity in mouse models of obesity and metabolic syndrome. The fifth paper (PMID 41588687, Rapid Commun Mass Spectrom, 2026) is a doping-control metabolism study covered below. Five papers, all mice, cells, or in-vitro enzymes; none human.

The Human Side-Effect Dataset That Doesn’t Exist

A real side-effect profile requires four things: humans receiving the compound, a control group, systematic recording of everything that happens, and publication. SLU-PP-915 has none of the four. There is no adverse-event table for it anywhere in the human literature, because there is no human study. “No data” is literal here, and it cuts both ways: nothing proves harm, and nothing demonstrates safety in people — the same absence we mapped for the copper peptide AHK-Cu, another compound sold on a reputation its studies never built.

PERSONAL OBSERVATION — PI EDITORIAL

Reading these five papers side by side, what struck us is how much rhetorical weight “exercise mimetic” carries and how little of it is about safety. The papers are careful — the compounds mimic specific exercise-induced changes in mouse muscle. By the time that reaches a product page it has become “get the benefits of exercise without the gym,” a promise no study made and none tested for harm. The gap between “induces an exercise gene program in mice” and “safe substitute for training in humans” is the entire missing dataset, hiding behind a catchy label.

The “Exercise in a Pill” Claim Is a Rodent Finding

The headline that sells this compound deserves precise reading. In mice, SLU-PP-915 and its predecessor induce gene-expression and physiological changes that overlap with aerobic exercise: both robustly induce Ddit4, a gene switched on by acute aerobic exercise, at levels matching or exceeding treadmill running depending on the muscle, and 915 synergized with training to further raise Ddit4 and mitochondrial gene expression (PMID 41421047) — a real, specific finding, in mice. It is not evidence that a person can replace exercise with a capsule, and it is not a safety statement: mimicking one arm of exercise biology says nothing about what else the drug does to a human heart, liver, or hormonal system over time. “Exercise in a pill” describes a rodent gene program, not a human-risk verdict.

What SLU-PP-332’s Data Can and Can’t Lend

SLU-PP-332 is the argument-by-proxy in every optimistic SLU-PP-915 writeup, and the more-studied molecule of the pair: the acute-exercise work (PMID 36988910) and the metabolic-syndrome work (PMID 37739806) are both about 332. What that lends 915: family-level plausibility that pan-ERR agonism drives exercise-like metabolic changes in mice. What it cannot lend: human numbers, because 332’s file is also entirely preclinical. Borrowing 332’s mouse reputation to imply 915’s human safety is an inference stacked on an inference.

Oral vs Injected: What the Studies Actually Used

What distinguishes SLU-PP-915 from its predecessor is oral bioavailability. In the 2026 mouse study, 915 was given both intraperitoneally and orally, with comparable exercise-capacity efficacy by the oral route after adjusting for systemic exposure (PMID 41421047) — which is why research-market 915 commonly appears as capsules. What “orally active in mice” does not establish is a human oral dose, an absorption profile in people, or any tolerability data.

PRACTICAL NOTES — HANDLING AN ORAL RESEARCH SMALL MOLECULE

  • The mouse study used intraperitoneal and oral routes — neither is a human dosing recommendation
  • A batch-matched COA is the only evidence a capsule or vial contains SLU-PP-915 at the stated quantity, not a look-alike ERR agonist
  • Oral bioavailability in mice does not translate to a known human dose — this page gives none
  • Everything in this channel is sold strictly for non-human research use

Why “No Reported Side Effects” Isn’t “No Side Effects”

The most common safety sentence written about SLU-PP-915 — “no side effects have been reported” — is technically true and structurally empty. Reporting requires a mechanism: trials with adverse-event logging, a pharmacovigilance system, published case reports. As an unapproved compound sold outside medicine, SLU-PP-915 has none of them. Absence of evidence here reflects absence of surveillance, not surveillance returning a clean result — which is exactly why the sentence means so little.

What Users Report: Self-Reported Effects From Reddit

The page above has no human data, and Reddit does not fill the gap: nobody there describes taking SLU-PP-915. We searched Reddit on September 5, 2026, found 95 relevant posts from 2024 to 2026, and read the comment threads of nine, across r/SLUPP332, r/BiohackingU, r/amino_asylum, r/PeptideGuide, r/BodyHackGuide, r/Peptidesource, r/NooTopics, r/Retatrutide and r/ResearchCompounds. Every one is about SLU-PP-332, the parent compound. What follows is about SLU-PP-332, labelled as such throughout, as the closest available analog. Everything below is paraphrased and linked, uses no usernames, and describes products nobody verified. One more caveat: the mouse studies injected SLU-PP-332; Reddit users swallow it, at doses spanning a thousand-fold, usually alongside retatrutide or another GLP-1.

Heat and sweating are the most consistent thing people report on SLU-PP-332. At least a dozen distinct posters describe running hot: one on 250 mcg twice a day had to shower and change after a dose by day three, and a 2026 commenter four days into 1 mg each morning described pouring armpits and clammy hands (r/SLUPP332). The most-upvoted write-up, on 400 mcg a day, noted a brief temperature rise after each dose; in that thread a man on 250 mcg three times a day, stacked with 5-Amino-1MQ, MOTS-c and L-carnitine, soaked his bed for two hours and had stomach cramps (r/amino_asylum).

Many describe a stimulant-like arc on SLU-PP-332: hours of energy, then a crash. The r/amino_asylum author got two to three hours of euphoric energy, then had to lie down for an hour, and woke at one or two in the morning unable to sleep again; two commenters reported the same waking (thread). At least seven people describe the afternoon crash, including a man on 1 mg twice a day who called it a sleeping pill (r/SLUPP332). A commenter who escalated to 200 mg twice a day alongside retatrutide returned two weeks later to warn of fatigue and brain fog (r/BiohackingU). Five posters said SLU-PP-332 improved their sleep; a small 2026 thread reports vivid dreams, “from a black and white dreamscape to IMAX” (r/NooTopics).

The most alarming SLU-PP-332 reports are panic attacks and cardiac sensations. A new user described tunnel vision and extreme anxiety about 45 minutes after an oral dose, gone within ten minutes; the reply came from someone who had taken SLU-PP-332 uneventfully for months before the same panic hit, returned the next day, stayed, and took about two months to fade (thread). Another man there, also on retatrutide, woke with a heavy chest, breathlessness and a racing heart and suspected he had been sold clenbuterol. Replies blamed low blood sugar, a stress tic or a fake product. Others note a higher daytime heart rate (r/PeptideGuide); the poster running 100 mg a day said his beta blocker might mask any rise (r/BiohackingU).

Just as many people felt nothing from SLU-PP-332, and the community disagrees about the dose by a factor of a thousand. More than ten distinct posters report no effect, at doses from 750 mcg to 600 mg a day (thread), including a coach who says a lab-tested product did nothing for more than twenty clients (r/Retatrutide). Others report the opposite, among them a two-week user with chronic fatigue who had his first jog in three years (thread). A woman three weeks into microgram doses reported new shooting pains behind the knees and visible veins, and was told her dose was too low to do anything (r/Peptidesource). Threads argue whether microgram capsules are placebo at a markup or milligram doses are reckless; one commenter noted that no oral SLU-PP-332 study exists in any animal (r/ResearchCompounds), and a newcomer asking how fast it works heard anything from minutes to days (r/BodyHackGuide).

HOW TO READ SELF-REPORTS

Nothing here is about SLU-PP-915. The anecdotes concern SLU-PP-332, a different molecule, taken by a route the animal studies never used, at doses nobody agrees on, by people usually on something else too. Heat and sweating fit the raised energy expenditure ERR agonism produced in mice; the panic attacks, crashes and insomnia have no counterpart in the published record because no one has looked. Without a denominator, a verified product or a control group, none of this says how often anything happens or whether SLU-PP-332, let alone SLU-PP-915, caused it.

The Doping-Control Angle: Human Liver Metabolism in a Test Tube

The closest the literature gets to “human” is a 2026 anti-doping study from the German Sport University Cologne (PMID 41588687). Because ERR agonists trigger physiological processes resembling exercise, the authors treated SLU-PP-332 and SLU-PP-915 as potential performance-enhancing substances and worked out how to detect them, studying their breakdown using human liver S9 fraction and human liver microsomes — human enzymes in a dish, not human subjects. The metabolism differed: SLU-PP-332 produced nine metabolites (six Phase-I and three Phase-II conjugates), while SLU-PP-915 produced only Phase-I transformation products, seven in total, three confirmed by chemical synthesis and NMR. Two things follow. First, SLU-PP-915 is squarely on the radar of sports drug-testing programs. Second, and this is the honest reframe, a metabolism study tells you how the body would chemically process the molecule, not whether doing so is safe — a detection roadmap, not a toxicology report.

Doses: What the Mouse Studies Administered

This is where honest coverage has to disappoint. The abstracts describe the route and design — intraperitoneal and oral dosing, efficacy “adjusted for systemic exposure” (PMID 41421047) — but never report the milligram-per-kilogram dose given to the mice, the one number a person would need to attempt any translation. Even if they did, a mouse mg/kg would not convert to a human dose. No human-equivalent dose can be responsibly derived here, and we won’t invent one; this page gives no dosing advice.

DID YOU KNOW

Every efficacy result for SLU-PP-915 comes from mice, and every metabolism result from human liver enzymes in a test tube (PMID 41588687) — no living human appears anywhere in its published record. What it does in a person over time is untested in our species.

Stacking SLU-PP-915: Exercise, GLP-1s, and the Missing Studies

The combinations people actually run — SLU-PP-915 alongside training, or paired with a GLP-1 agonist for weight loss — have no published safety data in any species. The one relevant data point is that 915 plus exercise training raised mitochondrial gene expression in mice more than either alone (PMID 41421047) — a synergy finding about gene expression, not a safety clearance for stacking. The adjacent, better-studied metabolic evidence lives on our visceral fat-loss guide and peptides-for-energy overview.

How This Compares to Compounds With Real Safety Data

It is worth being blunt about the gap. When we write up eloralintide or cagrilintide, we can quote nausea rates against a placebo column from human trials. For SLU-PP-915 there is no active-arm rate and no placebo column, because there is no human arm — only vehicle-versus-treatment comparisons in mice. A mouse “exercise-like benefits” finding and a human trial’s adverse-event rate are not two points on one scale; they come from different species measured in different ways. More unknowns is the only defensible way to describe the comparison — the same verdict our 5-Amino-1MQ page reaches for that compound’s identical rodent-only file.

Where Lab Data Stops: The Research-Product Reality

With a trial-backed drug, the research-vial problem is that the vial doesn’t inherit the trials. With SLU-PP-915 it is starker: there are no human trials to inherit, so the product rests entirely on its own documentation. The gap shows up three ways: identity and purity (a batch-matched COA is the only evidence a capsule or vial contains SLU-PP-915 at the stated quantity), dose arithmetic (working out what is in each capsule, or reconstituting powder with bacteriostatic water, is on the buyer), and no reference point — there is no “trial-grade experience” to compare against, because none was run. Everything in this channel is sold strictly for non-human research use.

PERSONAL OBSERVATION — PI EDITORIAL

In listings we’ve reviewed, the pattern is consistent: SLU-PP-915 is sold with the vocabulary of a launched performance drug — “exercise in a pill,” “burn fat without the gym” — riding on five papers that never enrolled a person. We keep a simple rule for pages like this one: count the human studies before trusting the human-facing adjectives. Here the count is zero, and the most human thing in the whole file is a test tube of liver enzymes used to help drug-testers catch it.

Sourcing and Verification

For a compound with no human safety literature, product quality is the only safety variable you can actually influence. The checklist doesn’t change: a batch-matched COA naming the compound and quantity, independent third-party testing with a verifiable report number, and skepticism toward any listing pairing “clinically proven” language with mouse studies. (Disclosure: some links on this site are affiliate links; they don’t change what we report.) Our vendor reviews show what passing documentation looks like, and our guide library covers verification in depth.

US Regulatory Status

SLU-PP-915 is not an approved drug and has never been evaluated by the FDA for any purpose. It exists in a single channel: the research-chemical market, where it is sold for non-human research use with no regulatory review of identity, purity, or safety. There is no prescription or over-the-counter version. Its intellectual property is held by Saint Louis University, and ERR agonists are an area of active commercial interest, but as of this writing SLU-PP-915 is described in its own literature as a chemical tool for exploring ERR activation — not a compound in registered human trials. Athletes should also note it has already been flagged for sports drug-testing programs (PMID 41588687). When its clinical or regulatory status changes, this section changes with it.

Frequently Asked Questions

What are the side effects of SLU-PP-915?

Unknown in humans — literally. No human study of SLU-PP-915 has ever been published, so no human side-effect rates exist. The five published papers are in mice, cells, and human liver enzymes in a test tube. Side-effect lists elsewhere are not drawn from SLU-PP-915 human research, because none exists.

Is SLU-PP-915 safe?

No published human data answers that in either direction. Nothing documents harm in people; nothing demonstrates safety in people. Its reputation rests on exercise-like results in mice, which do not transfer directly to humans.

Is SLU-PP-915 really “exercise in a pill”?

That phrase overstates a specific rodent finding. In mice, SLU-PP-915 induces gene-expression and physiological changes that overlap with aerobic exercise, including the exercise-induced gene Ddit4. It is not evidence that a person can replace training with a capsule, and it is not a safety statement.

How is SLU-PP-915 different from SLU-PP-332?

Both are pan-ERR agonists, but SLU-PP-915 is a chemically distinct molecule designed to be orally bioavailable, whereas SLU-PP-332 must be injected. In mice, oral 915 matched injected 332 for exercise capacity after adjusting for systemic exposure. Neither has human safety data.

Will SLU-PP-915 show up on a drug test?

It is on the radar of anti-doping science. A 2026 study characterized SLU-PP-915 for sports drug testing and identified seven of its metabolites using human liver enzymes in vitro. Tested athletes should treat it as a detectable, testing-relevant substance.

Is SLU-PP-915 a peptide?

No. Despite being sold in the peptide research market, SLU-PP-915 is a small molecule — a thiophene-based pan-ERR agonist — with no amino-acid backbone. It works by activating nuclear receptors, a different mechanism than the peptides beside it on vendor menus.

Glossary of Terms

  • SLU-PP-915: an orally bioavailable small-molecule pan-agonist of the estrogen-related receptors, marketed as an “exercise mimetic.”
  • SLU-PP-332: the earlier, injection-only ERR agonist SLU-PP-915 was designed to replace; the source of most borrowed mouse data.
  • ERR (ERRα/β/γ): estrogen-related receptors, orphan nuclear receptors that regulate mitochondrial and metabolic genes; the target SLU-PP-915 activates.
  • Exercise mimetic: a compound that reproduces some biological effects of exercise; for SLU-PP-915 this is demonstrated in mice, not humans.
  • Ddit4: DNA damage-inducible transcript 4, a gene switched on by acute aerobic exercise and induced by SLU-PP-915 in mouse muscle.
  • Human liver microsomes / S9 fraction: preparations of human liver enzymes used in a test tube to study drug metabolism — not living human subjects.
  • COA (certificate of analysis): the lab document identifying a research product’s contents; batch-matched or it proves nothing.

References