Every pair below earned a page because someone plausibly has to pick between the two. Thirty compounds allow 435 pairings; generating all of them would be page count, not information.
GLP-1 & incretins
Tirzepatide vs SemaglutideThe most-asked comparison on the site, and the one with the most evidence behind it.Retatrutide vs TirzepatideRetatrutide adds a third receptor, glucagon, to tirzepatide's two.Retatrutide vs SemaglutideOne receptor versus three.Survodutide vs RetatrutideBoth add glucagon receptor activity to GLP-1.Mazdutide vs SurvodutideMechanistically close to interchangeable: both are GLP-1 plus glucagon dual agonists without a GIP arm.Cagrilintide vs SemaglutideNot really an either-or.
Growth & repair
HGH (Somatropin) vs TesamorelinSupplying growth hormone versus prompting the pituitary to release its own.Ipamorelin vs CJC-1295Two different ways to raise GH, frequently sold together.Tesamorelin vs IpamorelinBoth raise the body's own growth hormone, by different doors: tesamorelin at the GHRH receptor, ipamorelin at the ghrelin receptor.HGH (Somatropin) vs CJC-1295The most common substitution question in this group, and the one where the evidence gap is widest.AOD-9604 vs HGH (Somatropin)AOD-9604 is a fragment of hGH, residues 176-191, isolated on the theory that this region carries the fat-metabolizing activity without the growth or glucose effects.BPC-157 vs TB-500The most common pairing in the repair category, usually sold and dosed together.BPC-157 vs GHK-CuBoth are sold for tissue repair, but they come from opposite ends of the evidence spectrum.TB-500 vs GHK-CuBoth trade on a parent molecule's reputation.KPV vs BPC-157Both are sold for gut inflammation, and KPV is the more interesting of the two on route: it is taken up by intestinal epithelium through the PepT1 transporter, which makes oral dosing mechanistically plausible in a way it is not for most peptides.MOTS-c vs SS-31Both target mitochondria, and they sit at opposite ends of development.
Longevity, immune & other
Semax vs SelankTwo Russian-developed peptides, frequently sold as a pair, both stabilized the same way with a Pro-Gly-Pro extension.DSIP vs SelankBoth are sold for sleep or calm and both come out of the same Soviet-era and Swiss research traditions.Humanin vs MOTS-cTwo peptides encoded in mitochondrial DNA rather than the nuclear genome, and the two compounds on this site with the most similar evidence profile: real human observational data about endogenous levels, and nothing at all about administering them.Epithalon vs Thymosin Alpha-1Both are short peptides with claimed immune or longevity effects, and they differ enormously in how independently they have been studied.NAD+ vs GlutathioneThe two compounds here most often sold as IV drips, and both share the same structural problem: the molecule being infused is not the one that has to get inside cells.5-Amino-1MQ vs NAD+Two different approaches to the same idea of raising NAD availability.SNAP-8 vs GHK-CuBoth are cosmetic peptides applied to skin, working on completely different problems: SNAP-8 targets expression lines by damping muscle signaling, GHK-Cu targets collagen and wound healing.