Side-by-side · Research reference
GHRP-2vsThymalin
Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.
APhase 2Reviewed15/42 cited
BHuman-MechanisticDraft12/40 cited
GHRP-2
Hexapeptide GHRP · Phase 2 (clinical diagnostic)
SQ · Multiple sites · 1–3×/day
Thymalin
Immune restorer · Russian peptide bioregulator
IM · Daily for 5–10 days · 1-2×/year
01Mechanism of Action
Parameter
GHRP-2
Thymalin
Primary target
Ghrelin receptor (GHS-R1a) on anterior pituitaryBowers 1990
T-cell precursors + thymus-axis maturation pathwayKhavinson 2002
Pathway
GHS-R1a → Gαq → Ca²⁺ → GH vesicle exocytosisBowers 2002
Modulation of T-cell differentiation + thymic hormone restoration in age-involuted thymusKhavinson 2002
Downstream effect
Strong GH pulse + IGF-1 elevation; appetite increase via ghrelin agonismBowers 2002
Restored T-cell populations, improved immune surveillance, reduced infection rates in elderlyKhavinson 2002
Feedback intact?
Yes, with somatostatin feedback active
—
Origin
Synthetic hexapeptide; developed by Bowers/Tulane group in the 1980sBowers 1990
Polypeptide fraction isolated from calf thymus extractKhavinson 2002
Antibody development
—
—
02Dosage Protocols
Parameter
GHRP-2
Thymalin
Frequency
1–3× per day
Once daily during cycle
Lower / starter dose
50 mcg per dose
2.5 mg / day
Duration
8–12 weeks on / 4 off (anecdotal)
5–10 day cycles, 1–2× per year
Reconstitution
Bacteriostatic water
Saline or bacteriostatic water
Timing
Pre-sleep + fasted preferred
Morning preferred
04Side Effects & Safety
Parameter
GHRP-2
Thymalin
Prolactin elevation
Mild but measurable
—
Hunger
Strong appetite increase
—
Injection site reaction
Mild erythema
Mild erythema at IM site
IGF-1 elevation
Strong; monitor with chronic high-dose use
—
Cancer risk
Contraindicated in active malignancy
—
Pregnancy / OB
Avoid
Avoid
Allergic reaction
—
Rare hypersensitivity to bovine-derived polypeptide
Autoimmune flare
—
Theoretical risk in active autoimmune disease
Long-term safety
—
Limited Western data
Absolute Contraindications
GHRP-2
- ·Active malignancy
- ·Pregnancy / breastfeeding
Thymalin
- ·Pregnancy / breastfeeding
- ·Bovine protein hypersensitivity
Relative Contraindications
GHRP-2
- ·Untreated diabetes
Thymalin
- ·Active autoimmune disease
- ·Concurrent immunosuppressant therapy
05Administration Protocol
Parameter
GHRP-2
Thymalin
1. Reconstitution
Add 2 mL bacteriostatic water to 5 mg vial → 2.5 mg/mL.
Add 1–2 mL saline or bacteriostatic water per 10 mg vial.
2. Injection site
SQ — abdomen or thigh. Rotate sites.
Intramuscular — deltoid or gluteal. Rotate sites.
3. Timing
Pre-sleep + fasted preferred.
Morning preferred during cycle.
4. Storage
Lyophilised: room temp, light-protected. Reconstituted: refrigerate ≤30 days.
Lyophilised: refrigerate, light-protected. Reconstituted: use immediately.
5. Needle
29–31G, 4–8 mm insulin syringe.
23–25G, 25–38 mm IM needle.
06Stack Synergy
GHRP-2
+ CJC-1295 (no DAC)
StrongGHRP-2 + CJC-1295-no-DAC is a higher-amplitude alternative to the ipamorelin + CJC-1295 stack. GHRP-2 produces a stronger pulse but with cortisol + prolactin signal — choose when maximum GH amplitude is the goal and the side-effect tolerance is acceptable.
- GHRP-2
- 100–200 mcg SQ · pre-sleep
- CJC-1295 (no DAC)
- 100 mcg SQ · same injection
- Primary benefit
- High-amplitude GH pulse, body composition
Thymalin
+ Thymosin α-1
ModerateThymalin is a polypeptide complex; Thymosin α-1 is a single purified peptide. Both target the thymus-axis but at different levels — Thymalin restores broad thymic signaling; Tα-1 provides a specific molecular activator. Anecdotally combined for elderly immune support.
- Thymalin
- 5–10 mg IM · daily × 7 days
- Thymosin α-1
- 1.6 mg SQ · 2× weekly during the cycle
- Primary benefit
- Broad thymic restoration + targeted immune activation