GHRP-2 common uses, half-life, side effects and more

GHRP-2 is a synthetic peptide that makes the pituitary release its own growth hormone. It copies the action of the hunger hormone ghrelin so it also increases appetite. It is approved in Japan as a single injection used to test whether someone lacks growth hormone. That is a diagnostic use rather than a treatment. It is approved nowhere else and is sold elsewhere as an unregulated research chemical. It also raises cortisol and prolactin. That is the main reason many people choose ipamorelin instead.

• Raising growth hormone without injecting growth hormone itself
• Deliberate appetite stimulation when eating more is the goal
• Recovery, sleep, and body composition (community use)
• Testing for growth hormone deficiency (the approved use in Japan)
• Stacking with a growth hormone releasing hormone analog

One to three times daily in community practice

The approved diagnostic dose for adults is a single 100 mcg injection into a vein taken fasting. Children are dosed at 2 mcg per kg into a vein up to a 100 mcg cap. Community practice is 100 to 300 mcg under the skin one to three times a day. One clinic chart review used 100 mcg three times a day alongside two other peptides. That review covered 14 men and ran no control group. Those amounts do fall inside the range people have received under the skin in studies. The claim that about 100 mcg saturates the pituitary is false. Growth hormone kept climbing at twice that dose and roughly doubled again at ten times it. The 100 mcg figure is a diagnostic dose for a vein rather than a ceiling for an injection under the skin.

The measured half-life is about 33 minutes. That figure comes from the only human pharmacokinetic study. It gave a single dose into a vein to ten children. Nobody has measured the half-life in adults or after an injection under the skin. The growth hormone rise peaks around 25 minutes and is over well before the next natural pulse.

• A feeling of heat or warmth affecting about one in six people
• Stomach rumbling
• Low blood pressure, nausea, or stomach discomfort
• Drowsiness
• Increased hunger and food intake
• Headache or dizziness

GHRP-2 activates the ghrelin receptor on the pituitary and in the hypothalamus. The pituitary then releases its own growth hormone. That growth hormone raises IGF-1 from the liver. One human experiment raised the brain's brake on growth hormone artificially. The GHRP-2 response held steady while the response to the natural releasing hormone fell by nearly forty percent. It does not work by lowering that brake. It works in spite of it. It also leans on your own growth hormone releasing signal. People whose receptor for that signal is broken still respond but at a small fraction of the normal size. It also stimulates the stress axis and raises cortisol, ACTH, and prolactin. The one study that compared it with ipamorelin head to head found ipamorelin left cortisol and ACTH alone. That study was done in pigs. Neither compound moved prolactin in it.

GHRP-2 has a genuine human evidence base. It is an approved diagnostic in Japan and has published dose-response studies in adults and children. The evidence that it does anything useful over the long run is much weaker. The only controlled trial of long-term use gave a nasal spray to 126 short children for 48 weeks and found no growth benefit over placebo. Earlier uncontrolled studies had reported faster growth. Those gains did not survive a control group. The longest human exposure on record is 12 months in ten children given it by mouth.

• It is banned in sport at all times under the growth hormone section of the prohibited list
• A single dose raises cortisol enough to serve as a clinical test of adrenal function so this is a real stress-hormone response rather than a lab curiosity
• Nobody has measured what repeated dosing does to cortisol over weeks or months
• Growth hormone and IGF-1 drive cell growth so it is not for anyone with a current or past cancer
• Its approved label contraindicates use in pregnancy and animal studies show it passes into milk
• A seized vial sold as GHRP-2 was found to contain a different and uncharacterized peptide