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Growth hormone secretagogue — selective pentapeptide (research compound) · safety
Ipamorelin side effects
The ipamorelin side effects reported most often are any side effect appearing after treatment started and no specific common reaction has been isolated. The full list is below, with the cited trial report cited at the bottom of the page.
Rarer, but worth being able to spot: unknown long-term risk.
The sources describe these effects in relation to the dose and to the early weeks.
Ipamorelin is a peptide five amino acids long. It makes the pituitary gland let out a pulse of growth hormone. Clinics and sellers offer it for muscle gain, fat loss, deeper sleep and faster recovery — the things people expect of growth hormone.
The pulse itself is measured and real. What follows from the pulse is not. The two completed trials tested how quickly the gut restarted after bowel surgery, and neither one beat placebo. No trial has measured muscle, fat, sleep or aging.
At a glance
Common reactions listed
2
Serious reactions listed
1
Boxed warning
No label exists
Strongest source
Human trial
Common reactions
The full list, as reported across the available trial evidence. There is no approved label to read frequency bands off, so these are the trials’ own figures.
| Reaction | Frequency |
|---|---|
| Any side effect appearing after treatment started | 87.5% of the ipamorelin group against 94.8% on placebo, across 114 patients in the week after bowel resection |
| No specific common reaction has been isolated | The published reports say people handled it well and name no distinct common reaction. The trials were never designed to characterize one outside post-surgical care |
Serious reactions to watch for
These are rarer, and they are the ones clinicians monitor for. Seek medical care if you have symptoms.
| Reaction | Frequency |
|---|---|
| Unknown long-term risk | No long-term safety data exists. The longest human exposure on record is seven days of intravenous dosing in hospital — monitor |
When to seek medical care
The trial report does not give a separate list of serious reactions. There is also no approved label. That gap does not mean serious reactions cannot happen. This compound has been studied in fewer people and for less time than an approved drug.
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When these effects tend to occur
The cited evidence describes these effects in relation to the dose and to the early period of taking it, rather than as a constant background throughout.
When a study reports how side effects changed over time, it describes the group as a whole. It cannot predict one person’s experience.
Common questions
How long do ipamorelin side effects last, and do they go away?
The sources do not commit to a set number of days. What they describe is a pattern — reactions cluster after you start and after each increase, then ease while the dose is held steady. Any page quoting an exact number of days is quoting something the sources do not say.
What are the most common ipamorelin side effects?
Any side effect appearing after treatment started and no specific common reaction has been isolated — the table above has the rest, each with its frequency band and source.
Does ipamorelin have a boxed warning?
No, because a boxed warning is part of an FDA-approved label and ipamorelin has no approved label. That reflects what regulatory review has and has not covered, not a finding that serious risks were looked for and ruled out.
Can the ipamorelin dose be lowered if side effects are hard to tolerate?
That decision belongs to the prescribing clinician. No approved schedule exists for this compound, so there is no labeled framework for adjusting a dose. That leaves the prescriber as the only place the decision can sit.
Does ipamorelin cause hair loss?
Hair loss is not among the reactions listed on this page for ipamorelin, because the cited trial report cited here does not carry it. Anything missing from the tables is outside what can be sourced here rather than ruled out, and a symptom that worries you belongs with a clinician.
Is fatigue a listed ipamorelin side effect?
No — the cited trial report cited here does not list it. That describes what was reported, not proof that the symptom cannot happen.
Is constipation a listed ipamorelin side effect?
Not separately. If a source groups stomach and gut events together, this page keeps that group intact. It does not invent named reactions the source never listed.
What should someone do about a serious ipamorelin reaction?
Contact a clinician promptly, and emergency services if symptoms are severe or getting worse quickly. The section above describes what those reactions actually look like, so they can be spotted early rather than explained away.
Do the frequencies on this page mean the chance it happens to one person?
No. These figures describe groups in a study. A band shows how often a reaction appeared under that trial’s conditions. It cannot predict what will happen to one person.
Related
The schedule these reactions were recorded against, the comparisons, and the sourcing rules behind every grade on this page.
Ipamorelin without an approved label: what exists instead
Which ipamorelin amounts the trials actually gave
Ipamorelin concentration and dose-draw tool
The generic calculator behind the ipamorelin one
Where ipamorelin sits among the source-checked pages
Where ipamorelin stands with the regulator, and when
Why some ipamorelin values are missing on purpose
- Beck DE, Sweeney WB, McCarter MD; Ipamorelin 201 Study Group. Prospective, randomized, controlled, proof-of-concept study of the ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. Int J Colorectal Dis 2014;29(12):1527-34retrieved 2026-08-12Human trial
- Dominikowski A, Rękoś Z, Olejarz M, Szczepanek-Parulska E, Domin R, Ruchała M. The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration. Front Endocrinol 2026;17 — Table 1, ipamorelin safety-signal rowretrieved 2026-08-12limited human data