Head to head

Hexarelin vs MK-677

GH secretagogue

Side-by-side on recovery and sleep, dosing, kinetics and evidence — with an honest verdict at the end.

Verdict

Route decides this one, not potency

On overlap and evidence these are close enough that the data cannot pick a winner. What it can tell you is that Hexarelin means a needle and a reconstitution step and MK-677 does not. For most people that, plus whether they will actually keep to once daily dosing, is what really decides it.

What you are actually choosing between

Both are classed here as growth hormone secretagogues, so this is a within-class choice: the mechanism is broadly shared and what separates them is kinetics, route, and how much has actually been tested.

The overlap is recovery and sleep and muscle growth. On this site's goal weighting — an editorial priority score, not a measure of effect size — Hexarelin rates 3/5 for recovery and sleep and MK-677 rates 5/5. Outside that overlap only MK-677 goes further, carrying weight for appetite control; Hexarelin's declared goals stop at the overlap.

The evidence

Neither has an evidence edge — both sit at the same tier. Hexarelin: controlled human trials behind it, without an approval; human GH-response data is real, but the response blunts within weeks. MK-677: controlled human trials behind it, without an approval; never approved, and trials flagged higher fasting glucose. Anyone telling you one is clearly better supported than the other is going beyond what is published.

How they differ in practice

Hexarelin is a subcutaneous injection and an intramuscular injection; MK-677 is taken by mouth. That is the difference most people actually feel: Hexarelin means reconstituting a vial and injecting; MK-677 does not require either. If needles are the deciding factor, this line settles it before any of the rest matters.

The kinetics are roughly 24× apart — 24 h for MK-677 against 1 h for Hexarelin — and yet both are dosed once daily. That schedule is convention rather than clearance, which is worth knowing before you assume the two behave the same way between doses.

Committed time differs: Hexarelin runs 4 weeks, MK-677 runs 16 weeks.

Risk and difficulty

MK-677 is rated intermediate here and Hexarelin advanced. That rating is about how much can go wrong in handling, dosing and monitoring, not about how well either works.

Source notes

What the evidence actually says

Verbatim, so you can check the verdict above against what it was built from.

Hexarelin

Synthetic hexapeptide ghrelin receptor (GHS-R1a) agonist and one of the most potent GH secretagogues studied in humans, with additional cardiac data. Its defining practical problem is tachyphylaxis: repeated dosing blunts the GH response over roughly two to four weeks, which is why it is cycled short rather than run continuously. It also lacks the selectivity of ipamorelin, so prolactin and cortisol elevation are expected at higher doses.

MK-677 (Ibutamoren)

Orally active, long-acting ghrelin receptor (GHS-R1a) agonist that raises GH and IGF-1 for around 24 hours per dose. It has been through multiple human trials, including a two-year study in older adults, but was never approved for any indication and trials also flagged increased fasting glucose and reduced insulin sensitivity. It is a non-peptide small molecule, so it is taken by mouth rather than injected.

Side by side

The numbers

Hexarelin compared with MK-677
Attribute	Hexarelin	MK-677
Class	GH secretagogue	GH secretagogue
Routes	Subcutaneous, Intramuscular	Oral
Dose range	50 mcg–200 mcg (typical 100 mcg)	10 mg–25 mg (typical 15 mg)
Frequency	Once daily	Once daily
Half-life	1 h	24 h
Cycle length	4 weeks	16 weeks
Experience	Advanced	Intermediate
Evidence	Controlled human trials	Controlled human trials
Contraindications	Pregnant / nursing Active malignancy Under 18	Pregnant / nursing Active malignancy Under 18
Side effects	Marked receptor desensitisation — the GH response falls off within a few weeks of continuous daily use, so cycles are kept short with washout periods Raises prolactin and cortisol more than ipamorelin does Strong hunger spike within 20 to 30 minutes of dosing Water retention, puffiness and numb or tingling hands Head rush, flushing or transient light-headedness after injection Injection site irritation	Pronounced increase in appetite, often within the first few days Water retention, puffiness in the face and ankles, and rapid scale weight gain Raised fasting blood glucose and reduced insulin sensitivity — a real concern for anyone prediabetic or diabetic, and worth monitoring with bloodwork on longer runs Lethargy or grogginess the morning after a pre-bed dose Numbness or tingling in the hands, sometimes carpal-tunnel-like Vivid dreams and deeper but occasionally disrupted sleep Mild joint aches at higher doses

Turn a typical dose into a mark on the syringe: Hexarelin

Goals

Where they overlap, and where they do not

Goal	Hexarelin	MK-677
recovery and sleep	Hexarelin: 3/5	MK-677: 5/5
muscle growth	Hexarelin: 4/5	MK-677: 4/5
injury repair	Hexarelin: 3/5	MK-677: 2/5
longevity	Hexarelin: 1/5	MK-677: 2/5
appetite controlone only	Hexarelin: —	MK-677: 5/5
fat lossone only	Hexarelin: 2/5	MK-677: —
skin and hairone only	Hexarelin: —	MK-677: 2/5

They overlap on 4 goals and diverge on 3. Weights are this site’s editorial priority score out of 5 — how central a goal is to why people use a compound. They are not effect sizes and two 5s do not mean two equal results.

Go deeper

MonographHexarelinMechanism, protocol, storage, sources.MonographMK-677 (Ibutamoren)Mechanism, protocol, storage, sources.ToolReconstitution calculatorTurn either dose above into a mark on the syringe.

Other comparisons with these two

Educational information only, not medical advice. Talk to a licensed clinician before starting, changing, or stopping anything.