Thymosin Beta-4 vs MK-677 (Ibutamoren)
Side-by-side comparison of key properties, dosing, and research.
Recovery & RepairAnti-Aging & Longevity
Thymosin Beta-4Growth Hormone Peptides
MK-677 (Ibutamoren)- Summary
- Thymosin Beta-4 is an endogenous 43-amino acid peptide that is the primary intracellular actin sequestering peptide. It promotes tissue repair, reduces inflammation, regenerates hair follicles, and protects cardiac tissue. Closely related to TB-500 (the active fragment), it is used for systemic tissue recovery and anti-aging.
- MK-677 (Ibutamoren) is an orally active, non-peptide ghrelin receptor agonist that increases growth hormone and IGF-1 levels. Unlike injectable GHRPs, it can be taken orally and has a 24-hour half-life, making it convenient for sustained GH optimization.
- Half-Life
- Not well characterized; likely similar to TB-500 (~1–2 hours)
- 24 hours
- Admin Route
- SubQ, IM
- Oral
- Research
- —
- —
- Typical Dose
- 5–10 mg
- 10–25 mg
- Frequency
- 2x per week (loading), then 1x per week (maintenance)
- Once daily
- Key Benefits
- Systemic tissue repair and regeneration
- Promotes cardiac recovery after myocardial infarction
- Hair follicle regeneration and anti-hair-loss
- Anti-inflammatory (systemic)
- Wound healing acceleration
- Neuroprotection after brain injury
- Protects against ischemia-reperfusion injury
- Anti-aging at cellular level
- Synergizes powerfully with BPC-157
- Increases lean muscle mass
- Enhances bone density
- Improves sleep quality and REM sleep
- Accelerates recovery from training
- Increases appetite
- May improve skin elasticity and appearance
- Supports fat loss while maintaining muscle
- Oral administration — no injections required
- 24-hour half-life allows once-daily dosing
- Side Effects
- Generally very well tolerated
- Injection site reactions
- Mild fatigue at initiation (repair signaling)
- Rare: mild inflammatory response
- +1 more
- Increased appetite (significant in some users)
- Water retention and puffiness
- Elevated blood glucose / insulin resistance (monitor in diabetics)
- Lethargy initially
- +2 more
- Stacks With
- —
- —