Comparison
GHRP-6 vs Rapamycin
Side-by-side of GHRP-6 and Rapamycin. Every row below is pulled from the compound schema and will update as our data grows. For deeper reads, follow through to each compound page.
GHRP-6
First-generation hexapeptide ghrelin-receptor agonist. Pioneered the GHS-R1a pathway in the 1980s. Produces the strongest hunger response among GHRPs and a mo.
Rapamycin
Rapamycin for longevity: sirolimus, an mTOR inhibitor with ITP mouse lifespan data. Off-label geroprotective dosing remains investigational.
Effects at a glance
GHRP-6
- •First-generation hexapeptide ghrelin-receptor agonist; foundational to the GHRP class
- •Strongest appetite stimulation of any synthetic GHRP at equivalent GH doses
- •Produces measurable cortisol and prolactin rise alongside the GH pulse
- •Anecdotal protocols use 100 to 200 mcg subcutaneously 2 to 3 times daily on an empty stomach
- •Largely superseded by ipamorelin (cleaner profile) and GHRP-2 (stronger pulse) for body-composition use
- •Banned by WADA under S2; detection methods validated in accredited labs
Rapamycin
- •Inhibits mTORC1 signaling by binding FKBP12, reducing protein synthesis and relieving autophagy suppression
- •ITP mouse program reproduced lifespan extension of ~10 to 25% across multiple genetic backgrounds and sexes
- •Mannick trials showed improved influenza vaccine response in elderly adults using analogs of rapamycin
- •PEARL human trial reported acceptable safety at 5 to 10 mg weekly with some functional and lean-mass signals
- •Common dose-limiting adverse effects include stomatitis, acne-like rash, and mildly elevated lipid markers
- •CYP3A4 substrate: grapefruit, ketoconazole, and clarithromycin substantially raise rapamycin exposure
Side-by-side
| Attribute | GHRP-6 | Rapamycin |
|---|---|---|
| Category | peptide | pharmaceutical |
| Also known as | Growth Hormone Releasing Peptide 6, SKF-110679, Histidyl-D-Tryptophyl-Alanyl-Tryptophyl-D-Phenylalanyl-Lysinamide | Sirolimus, Rapamune |
| Half-life (hr) ↗ | 0.5 | 62 |
| Typical dose (mg) ↗ | 0.1 | 6 |
| Dosing frequency | 2-3x daily | weekly (longevity protocols); daily for transplant indication |
| Routes | subcutaneous, intravenous | oral |
| Onset (hr) | 0.25 | 1 |
| Peak (hr) | 0.5 | 2 |
| Molecular weight | 872.44 | 914.17 |
| Molecular formula | C46H56N12O6 | C51H79NO13 |
| Mechanism | Hexapeptide agonist of GHS-R1a (ghrelin receptor). Suppresses hypothalamic somatostatin and stimulates pituitary somatotrophs, with strong central NPY/AgRP appetite signaling and modest cortisol and prolactin release. | Binds FKBP12, and the resulting complex inhibits mTORC1, reducing protein synthesis and autophagy suppression downstream of nutrient and growth-factor signaling. |
| Legal status | Not FDA approved; research-use-only grey market; banned by WADA | Prescription only (off-label for longevity) |
| WADA status | banned | allowed |
| DEA / Rx | Not scheduled (research chemical) | Rx only (not a controlled substance) |
| Pregnancy | Insufficient data; not recommended | Not recommended |
| CAS | 87616-84-0 | 53123-88-9 |
| PubChem CID | 9919072 | 5284616 |
| Wikidata | Q5519921 | Q410174 |
Safety profile
GHRP-6
Common side effects
- intense hunger
- water retention
- vivid dreams
- head pressure or flushing
- tingling at injection site
- transient lethargy
Contraindications
- pregnancy
- active malignancy
- history of pituitary tumor
- uncontrolled diabetes
- prolactin sensitivity
Interactions
- CJC-1295: synergistic GH release; commonly co-administered(minor)
- sermorelin: additive GH release via parallel GHRH and ghrelin pathways(minor)
- insulin: sustained GH can blunt insulin sensitivity over weeks(moderate)
- corticosteroids: blunt GH response and amplify cortisol load(moderate)
Rapamycin
Common side effects
- mouth ulcers (stomatitis)
- acne-like rash
- GI upset
- altered lipid panel
- delayed wound healing
Contraindications
- active infection
- severe hepatic impairment
- planned surgery (delayed wound healing)
- pregnancy
- live vaccines within dosing window
Interactions
- strong CYP3A4 inhibitors (ketoconazole, clarithromycin, grapefruit): substantially raises rapamycin levels, toxicity risk(major)
- strong CYP3A4 inducers (rifampin, St John's wort): lowers rapamycin levels, reduced effect(major)
- ACE inhibitors: increased risk of angioedema(moderate)
- live vaccines: reduced vaccine efficacy due to immunosuppression(major)
Which Should You Take?
Rapamycin comes out ahead for most readers on the criteria we weight: 2 catalogued goals, prescription-only, oral dosing, with a Tier-A outcome catalogued. GHRP-6 is the right call when one of the conditionals below applies.
- → If your priority is growth-hormone axis, pick GHRP-6.
- → If your priority is appetite regulation, pick GHRP-6.
- → If your priority is healthspan extension, pick Rapamycin.
- → If your priority is immune support, pick Rapamycin.
Edge case: If you cannot self-administer injections, Rapamycin is the only oral option in this pair.
Default choice: Rapamycin. Wider use case, a Tier-A evidence outcome catalogued, and broader goal coverage. Reach for GHRP-6 only if your priority sits squarely in the goals it owns above.
This verdict is generated from each compound's schema (goals, legal status, evidence outcomes, dosing route). It updates automatically as our compound data evolves; the deeper read sits on each individual compound page.
Common questions
What is the difference between GHRP-6 and Rapamycin?
GHRP-6 and Rapamycin differ in category (peptide vs pharmaceutical), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, GHRP-6 or Rapamycin?
GHRP-6 half-life is 0.5 hours; Rapamycin half-life is 62 hours.
Can you stack GHRP-6 with Rapamycin?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
Go deeper