Peptide Comparison
MK-677 (Ibutamoren)vsIpamorelin
The oral growth hormone secretagogue that tricks your body into producing more GH — no needles required.
A uniquely selective growth hormone booster that tells your pituitary to release more GH without messing with your cortisol or other hormones—making it the 'clean' choice among growth hormone peptides.
At a Glance
Quick
comparison
Dose Range
MK-677 (Ibutamoren)
10–25 mg
Ipamorelin
100–300 mcg
Frequency
MK-677 (Ibutamoren)
Once daily
Ipamorelin
Multiple times daily
Administration
MK-677 (Ibutamoren)
Oral (capsule or liquid)
Ipamorelin
Subcutaneous injection
Cycle Length
MK-677 (Ibutamoren)
8-12 weeks
Ipamorelin
8-12 weeks
Onset Speed
MK-677 (Ibutamoren)
Moderate (1-2 weeks)
Ipamorelin
Moderate (1-2 weeks)
Evidence Level
MK-677 (Ibutamoren)
Moderate human trials (Phase 1-2)
Ipamorelin
Moderate human trials (Phase 1-2)
Efficacy
Benefit
ratings
Muscle and body composition
Recovery and athletic performance
Sleep quality and metabolic health
GH Selectivity
Recovery Support
Safety Profile
Technical Data
Compound
specifications
MK-677 (Ibutamoren)
Molecular Formula
C27H36N4O5S
Molecular Weight
528.7 g/mol
Half-Life
4-6 hours (IGF-1 elevation persists ~24 hours)
Bioavailability
High oral bioavailability
CAS Number
159634-47-6
Ipamorelin
Molecular Formula
C38H49N9O5
Molecular Weight
711.85 g/mol
Half-Life
2 hours
Bioavailability
High when injected subcutaneously
CAS Number
170851-70-4
Protocols
Dosing
tiers
MK-677 (Ibutamoren)
Ipamorelin
Applications
Best
suited for
MK-677 (Ibutamoren)
Older Adults (60+) Seeking Body Composition Improvements
MK-677 was designed for aging populations. It restores GH and IGF-1 to youthful levels, increases lean mass, and improves physical function in people over 60. A 2-year clinical trial showed a 1.1 kg gain in fat-free mass with only modest fat gain—ideal for maintaining strength in older age.
Athletes and Fitness Enthusiasts Wanting Recovery Support
Oral dosing makes MK-677 convenient for athletes. It enhances muscle protein synthesis, speeds recovery after intense training, and supports lean mass building without the hassle of injections.
People with Chronic Wasting or Protein Deficiency
Clinical trials show MK-677 helps treat protein-energy wasting in kidney disease and other conditions. It stimulates appetite (a feature in these populations) and preserves muscle tissue—making it useful for those losing mass despite good nutrition.
Ipamorelin
Clean GH Boost Seekers
If you want the benefits of increased growth hormone without spiking cortisol or other stress hormones, Ipamorelin is uniquely selective. Unlike GHRP-2 or GHRP-6, it won't raise your cortisol levels even at doses 200 times higher than needed for GH release.
Recovery-Focused Athletes
Ipamorelin shines for athletes who want better recovery between training sessions. The GH boost helps repair muscle tissue faster, and since it doesn't mess with other hormones, you can use it consistently without the rollercoaster effects.
Anti-Aging Enthusiasts
Growth hormone naturally declines as we age, contributing to muscle loss, fat gain, and reduced vitality. Ipamorelin offers a gentle way to restore more youthful GH levels without the risks of actual HGH therapy.
Those Recovering from Steroid Use
Research shows Ipamorelin can help counteract the muscle and bone-weakening effects of glucocorticoid medications. If you've been on steroids for medical reasons, this peptide may help you rebuild what you've lost.
Safety Profile
Side
effects
MK-677 (Ibutamoren)
Common
- Increased appetite
- Mild water retention or edema
- Elevated fasting glucose
Uncommon
- Joint or muscle pain
- Carpal tunnel syndrome or nerve compression symptoms
- Mild nausea or digestive upset
Serious
- Glucose dysregulation and diabetes risk
Ipamorelin
Common
- Mild headache
- Injection site reactions
- Water retention
- Increased appetite
Uncommon
- Tingling in hands or feet
- Joint stiffness
Serious
- Allergic reaction
Research Status
Safety
& evidence
MK-677 (Ibutamoren)
Evidence Level
Moderate human trials (Phase 1-2)
FDA Status
Research compound
Safety Overview
MK-677 has been studied in hundreds of humans over 2+ years and is generally well tolerated. Most side effects are mild and manageable, especially with lower starting doses. The lack of injection requirement makes it safer than injectable GH in terms of infection risk and sterility concerns. However, it is not FDA approved and should be viewed as a research compound.
Contraindications
- xUncontrolled diabetes or severe glucose dysregulation
- xActive cancer or high cancer risk requiring caution with IGF-1 elevation
- xPregnancy or breastfeeding
Ipamorelin
Evidence Level
Moderate human trials (Phase 1-2)
FDA Status
Research compound
Safety Overview
Ipamorelin has shown a favorable safety profile in both animal and human studies. What makes it stand out is its remarkable selectivity—it releases growth hormone without significantly affecting cortisol, ACTH, or other hormones. In clinical trials, it was well-tolerated with mostly mild, temporary side effects. Phase 2 trials in patients recovering from surgery showed no significant safety concerns compared to placebo.
Contraindications
- xActive cancer or history of cancer
- xPregnancy or breastfeeding
- xPituitary disorders or tumors
- xKnown allergy to peptide components
- xChildren and adolescents (growth plates still open)
Decision Guide
Which is
right for you?
Choose MK-677 (Ibutamoren) if...
- Building lean muscle mass and strength
- Improving overall body composition in aging adults
- Enhancing athletic recovery and performance
- Supporting metabolic health and fat loss
Choose Ipamorelin if...
- Muscle recovery and growth
- Anti-aging and vitality
- Body composition improvement
- Sleep quality enhancement