GHRP 6 side effects in human studies are mostly hormonal and short-lived. At a 1 mcg per kg IV dose, cortisol and prolactin about doubled in healthy men, and flushing was the main symptom reported in hospital testing.[1][9] Hunger is GHRP-6’s best-known effect, but it comes from animal and ghrelin studies, not a controlled human GHRP-6 trial.[3][4] FDA also cites a potential rise in blood sugar and immune reactions from impure compounded products.[12]

This guide sorts what is measured in people from what is assumed. For background, see our GHRP-6 profile, GHRP 6 dosage and the growth hormone peptides hub.

Where GHRP-6 safety data come from

We found no approval trials for GHRP-6. Human safety information comes from:

  • Short hormone studies in small groups of healthy men, mostly single IV doses in the late 1980s and 1990s.[1][2]
  • Diagnostic test studies in hospital patients, again with a single dose.[9][10]
  • Cuban stroke trials, where GHRP-6 was given with epidermal growth factor (EGF) twice daily for a week.[13][14]
  • A 2026 review that pulls together side effects reported across growth hormone-releasing peptides, including people using them without a prescription.[5]

No study followed people taking GHRP-6 for months.

Hunger and appetite

GHRP-6 releases growth hormone through its own receptor, the growth hormone secretagogue receptor,[15] which is also the receptor for ghrelin, the hunger hormone made mainly in the stomach:[4]

  • Rats: injected into the brain, GHRP-6 caused eating in a dose-related way, separately from its effect on growth hormone.[3]
  • Ghrelin in people: an IV ghrelin infusion made all nine volunteers in a London study eat more at a buffet, by 28% on average.[4]
  • Review: a 2026 review lists appetite changes among the reported side effects of this peptide class.[5]

We found no controlled human study measuring hunger or food intake on GHRP-6 itself. For people trying to lose weight, a hunger boost works against the goal. For a peptide in the same family with less effect on stress hormones in animals, see ipamorelin vs GHRP-6.

Cortisol and ACTH

GHRP-6 activates the body’s stress-hormone system (ACTH from the pituitary, then cortisol from the adrenal glands):

  • Single IV dose: in 18 healthy men, cortisol rose about twofold at 1 mcg per kg, but not at 0.1 or 0.3 mcg per kg.[1]
  • Repeated doses at night: four IV doses of 50 mcg raised overnight ACTH and more than doubled cortisol in the first half of the night compared with placebo.[6]
  • Route matters: a nasal dose showed a trend toward more ACTH without a cortisol rise, and an oral dose changed neither.[7]
  • As a test: because it reliably activates this system, 1 mcg per kg has been tried as a test for adrenal insufficiency, with no detectable side effects.[8]
  • FDA lists a potential effect on cortisol among its safety concerns.[12]

In pigs, GHRP-6 raised ACTH and cortisol while ipamorelin did not.[15] These are short rises after single doses; the effect of months of use is unknown. People with Cushing’s syndrome, adrenal problems or diabetes should not assume the rise is harmless.

Prolactin

Prolactin is another hormone released by the pituitary gland.

  • Healthy men: prolactin about doubled after 1 mcg per kg IV, but not at lower doses.[1]
  • Japan: prolactin and cortisol rose slightly but significantly after a 1 mcg per kg IV dose.[11]
  • First human study: LH, FSH, TSH and ACTH did not change with a 30-minute infusion of up to 2.5 mcg per kg; prolactin was not reported in the summary.[2]

Blood sugar and insulin

  • FDA: its compounding safety review cites a potential increase in blood glucose due to decreased insulin sensitivity.[12]
  • Human data: in a Japanese study, GHRP-6 did not change insulin or blood sugar, including over seven nasal doses given every 8 hours.[11]
  • Review: a 2026 review lists dysglycaemia (blood sugar disturbance) among side effects reported with this class.[5]

If you have diabetes or prediabetes, this is worth discussing before any growth hormone-related peptide.

Flushing and other short-term effects

  • Flushing: the only side effect seen with GHRP-6 in a Hamburg diagnostic study of 20 patients.[9]
  • No adverse events reported: in a 250-person diagnostic study using GHRP-6 plus GHRH,[10] and in the first human study, where it was described as safe and well tolerated.[2]
  • Sleep: repeated IV doses increased light (stage 2) sleep without changing deep sleep.[6]
  • Class effects: a 2026 review lists fluid retention, muscle and joint aches, and injection-site reactions across growth hormone-releasing peptides.[5]
  • Unusual blood levels: in a Cuban pharmacokinetic study, 4 of 9 men had unexpected spikes in GHRP-6 levels during clearance, which the authors called atypical.[17]

Serious adverse events in the stroke trials

The largest safety data set comes from Cuban stroke patients, who are seriously ill to begin with:

  • Phase I/II (36 patients): serious adverse events occurred in 9 of 16 on standard care and in 5 of 20 given EGF plus GHRP-6. Only two events, in one patient, were attributed to the treatment.[14]
  • Phase III COURAGE-2 (188 patients): serious adverse events occurred in 30 of 95 treated patients and 18 of 93 on standard care. None were judged treatment-related, and the difference was not statistically significant.[13]

These patients also received EGF, so the results cannot be pinned on GHRP-6 alone.

  • Immune reactions: FDA warns that compounded GHRP-6 may trigger immune reactions for certain routes because the peptide can clump and carry impurities.[12]
  • Compounding: FDA lists GHRP-6 as a significant safety risk for outsourcing facilities (since September 29, 2023)[12] and in category 3, nominated without adequate support, for traditional pharmacies on its May 14, 2026 list.[16]
  • Not approved: we found no FDA approval for GHRP-6.

Who should be especially cautious

Based on its hormone effects and FDA’s concerns, people who should talk to a doctor first include those with:[1][12]

  • Diabetes, prediabetes or insulin resistance
  • Cushing’s syndrome, adrenal disease or a pituitary tumor
  • High prolactin or unexplained breast symptoms
  • An eating disorder, or a goal of weight loss
  • Pregnancy or breastfeeding (we found no human data)

Questions to ask a clinician

  • Which blood tests (glucose, HbA1c, prolactin, cortisol, IGF-1) should we check?
  • Are my symptoms better explained by something we can test and treat?
  • Which approved options fit my goals?

This is general information, not medical advice.