Quick answer: the best-documented GHRP 2 side effects come from Japan’s label for its one-time diagnostic injection: a feeling of warmth in 16.0% of people, plus stomach rumbling, sweating, thirst, hunger, drowsiness, nausea and other mostly short-lived reactions.[1] GHRP-2 also raises prolactin, ACTH and cortisol, and clearly increases hunger.[3][4] FDA cites reports of increased insulin needs, infection, pancreatitis and deaths of critically ill study subjects, though causality has not been established.[2]
This guide covers each source of safety data, the hormone effects, what longer studies found, and who should be cautious. For background, see our GHRP-2 profile and the growth hormone peptides hub.
Where GHRP-2 safety data come from
Human safety information on GHRP-2 is real but limited:
- Japan’s label, based on a single 100 mcg IV dose used to diagnose growth hormone deficiency.[1]
- Small research studies from the 1990s and 2000s in healthy adults, older adults, children and critically ill patients, mostly lasting hours to weeks.[3][7][11]
- FDA’s compounding review, which placed injectable and nasal GHRP-2 on its list of substances that may present significant safety risks on September 29, 2023.[2]
No large or long-term controlled safety trial has been published.
Side effects listed on Japan’s label
Japan’s label groups reactions by how often they occurred:[1]
| How often | Reported reactions |
|---|---|
| 5% or more | Feeling of warmth (16.0%), stomach rumbling, raised white blood cell count |
| 0.1% to under 5% | Low blood pressure, nausea, stomach discomfort, bloating, drowsiness, runny nose, sweating, thirst, feeling dazed, cold sweat, hunger, tiredness, unsteadiness |
| Frequency unknown | Raised ALT (a liver enzyme), stomach pain, dizziness, shifts in white cell types, bitter taste, back pain, headache, facial flushing |
Most of these appeared around a single test dose. The label also says:[1]
- Pregnancy: do not use in women who are or may be pregnant.
- Breastfeeding: weigh the benefits; in rats, the drug passed into milk.
- Pituitary tumors: similar drugs given to people with pituitary adenomas have caused pituitary apoplexy (bleeding into the gland), with vision problems, headache and vomiting.
- Young children: it was not tested in children under 4.
Hunger and appetite
Increased hunger is the clearest effect of GHRP-2 outside the hormone system:
- Healthy men: during a 270-minute infusion under the skin, seven men ate 35.9% more at a buffet than on saline, and every one ate more.[4]
- Lean and obese adults: in 19 people, food intake rose about 10% at a low dose and 34% at a higher dose, regardless of weight.[5]
- Children: 7 of 10 children taking GHRP-2 by mouth for a year reported more appetite in the first 6 months, but their BMI score did not rise significantly.[6]
That can be welcome in people trying to gain weight, but it is a problem for anyone using GHRP-2 hoping to lose fat.
Cortisol, ACTH and prolactin
GHRP-2 is not selective for growth hormone. In six healthy young adults in Turin, single IV doses raised prolactin, ACTH and cortisol. The ACTH and cortisol rise was similar to that caused by CRH, the body’s own stress-hormone signal; the prolactin rise was smaller than with TRH.[3]
These were short rises after a single dose. In critically ill adults, a 21-hour infusion did not change their already high cortisol levels.[7] In pigs, GHRP-2 raised ACTH and cortisol while the related peptide ipamorelin did not; see GHRP-2 vs ipamorelin.[16]
Blood sugar and insulin
FDA says it is aware of reports of increased insulin requirements to maintain blood sugar in people given GHRP-2.[2] A 2018 review of growth hormone secretagogues as a class found them generally well tolerated but noted concern about rising blood sugar because of reduced insulin sensitivity.[9] A 2026 endocrine review listed abnormal blood sugar among the adverse effects clinicians see in people self-administering these peptides, along with prolactin and cortisol rises, appetite changes, fluid retention, muscle and joint aches, and injection-site reactions.[15]
Findings in critically ill patients
FDA’s safety list mentions deaths of critically ill study subjects, infection and pancreatitis in people who received GHRP-2, while stating that causality has not been established.[2] The published Belgian intensive-care studies used GHRP-2 infusions in people who were already severely ill.[7][8]
In one of them, 33 men with prolonged critical illness were randomized to 5 days of placebo, GHRP-2 alone or GHRP-2 with other hormones. By day 5, blood lactate and white blood cell counts had risen in the groups given GHRP-2 alone or with TRH, but not in the group that also received GnRH.[8] These trials were small and not designed to judge safety.
What longer use looked like
- Fading response: in 9 healthy men given 100 mcg under the skin daily for 5 days, the growth hormone peak fell from 83 to 51 micrograms per liter. This loss of effect is called tachyphylaxis.[10]
- 30-day infusion: in older adults, safety screening tests stayed normal during a month of continuous infusion.[11]
- Children: in six children given rising doses under the skin for 8 months, no adverse effects or toxicity were observed.[12] A nasal spray used for 6 to 24 months was described as well tolerated.[13]
- Single case: a woman in Japan with severe, long-standing anorexia nervosa used nasal GHRP-2 before meals for a year; the authors reported no obvious adverse effects and weight gain of 6.7 kg.[14]
These studies were small, so they cannot rule out rarer or delayed harms.
Product quality and immune risks
FDA’s reasons for listing injectable and nasal GHRP-2 also include possible immune reactions caused by clumped peptide (aggregation) or peptide-related impurities, and an unnatural amino acid that makes the product harder to test.[2] GHRP-2 sold online is not an approved medicine in the US, so its content, dose and sterility are not checked by FDA. For more, see our overviews of peptide side effects and injection-site reactions.
Who should be cautious
Talk carefully with a clinician before any GHRP-2 use if you:
- Are pregnant, trying to conceive or breastfeeding.[1]
- Have a known pituitary tumor.[1]
- Have diabetes, prediabetes or need insulin.[2]
- Are trying to lose weight, given the hunger effect.[5]
For doses that have been studied, see our GHRP-2 dosage guide. For related peptides, see GHRP-2 vs GHRP-6 vs hexarelin and ipamorelin side effects.
Questions to ask a clinician
- What human safety data support the way you want me to use GHRP-2?
- Will you check my blood sugar, IGF-1, prolactin and cortisol?
- Which symptoms should make me stop and call you?
- Is there an FDA-approved option for my goal?
Report suspected side effects to your clinician and to FDA’s MedWatch program. This is general information, not medical advice.
