Peptide Stack Checker
Pick 2 to 5 research compounds and see how their mechanisms relate — pair by pair, with the reasoning. It flags the combinations that compete for one receptor, the ones that overlap redundantly, and the ones that are genuinely complementary. For the vial math on a multi-peptide vial, use the stack & blend calculator instead.
Quick summary
- Every pair is graded synergistic, compatible, caution or conflict on mechanism — which receptor or pathway each compound acts on.
- Two compounds from the same receptor class (two GLP-1s, two melanocortins) return a conflict, because that is duplication rather than a second mechanism.
- This tool reports pharmacology only. It never suggests an amount, an order, or a schedule.
Metabolic & GLP-1
Recovery & repair
Growth hormone axis
Mitochondrial & longevity
Cognitive
Melanocortin & other
Common research stacks
The groupings that come up most often, each with the verdict our rules return. Open one to see the full pair-by-pair breakdown.
Distinct mechanisms that are commonly researched together.
Distinct mechanisms that are commonly researched together.
Distinct mechanisms that are commonly researched together.
Distinct mechanisms that are commonly researched together.
No documented mechanistic conflict between these two.
Distinct mechanisms that are commonly researched together.
Distinct mechanisms that are commonly researched together.
Competing for the same receptor, or additively hitting one pathway.
How the verdicts are decided
Every compound in the roster is tagged with the mechanism class it belongs to — incretin receptor agonist, ghrelin-receptor secretagogue, tissue repair, melanocortin agonist, and so on. A pair is graded by how those two classes relate, with specific well-documented pairings overriding the general class rule.
The order of resolution: a rule written for that exact pair wins first. Failing that, two compounds in the same class are graded by that class's rule — same-receptor classes return a conflict or a caution, complementary-mechanism classes return synergy. Failing that, the pair is graded by the class-to-class rule. If nothing matches, the pair is reported as compatible with no documented mechanistic interaction, which means exactly that: no documented interaction, not a positive finding of safety.
Stack checker FAQ
What does the stack checker actually check?
Mechanism overlap. For every pair in your selection it looks at what each compound acts on — which receptor or pathway — and reports whether those mechanisms are complementary, independent, overlapping, or in direct competition. It does not check doses, amounts, or timing.
What do the four verdicts mean?
Synergistic means distinct mechanisms that are commonly researched together. Compatible means no documented mechanistic conflict. Caution means the two overlap or pull against each other in a way worth understanding first. Conflict means they compete for the same receptor or hit one pathway additively, which is why they are studied separately.
Why can two GLP-1 compounds never be combined?
Semaglutide, Tirzepatide, Retatrutide and Liraglutide all act on the incretin receptor family. Running two together stacks agonism at the same receptors instead of adding a new mechanism, and every published escalation reference for each one assumes it is the only incretin present.
Does a Synergistic verdict mean the combination is safe?
No. It means the two mechanisms are distinct rather than competing, which is a statement about pharmacology and nothing else. Safety in humans is not established for these compounds — they are research chemicals, and this tool is educational.
Does the tool tell me how much to use or when?
No, and it never will. PepGuru publishes measurement math and mechanism references, not protocols. For the vial arithmetic on any compound in your stack, use the linked calculator.
Can I share a stack?
Yes. Copy link puts your exact selection in the URL, so anyone opening it sees the same analysis.
