What is sermorelin, the growth hormone secretagogue?
Sermorelin is a synthetic analog of growth hormone-releasing hormone (GHRH), the hypothalamic peptide that signals the pituitary gland to release growth hormone. Unlike exogenous recombinant human growth hormone (rhGH), sermorelin works by stimulating the pituitary’s own growth hormone production. This preserves the natural pulsatile release pattern and the pituitary’s feedback mechanisms.
Sermorelin has been studied since the 1970s and 1980s, with a substantial published literature on its effects on growth hormone secretion in healthy adults and older adults. It was the active ingredient in Geref, an FDA-approved drug discontinued in 2008, and licensed 503A pharmacies in the United States compound it with a prescribing clinician’s order.
Clinicians prescribing sermorelin typically use it for patients in growth hormone optimization protocols addressing body composition, recovery, and metabolic goals. The therapy requires clinician supervision because growth hormone axis modulation is not appropriate for everyone, and lab work before and during treatment is standard.
What is GHK-Cu, the copper peptide?
GHK-Cu (glycyl-L-histidyl-L-lysine copper) is a tripeptide that occurs naturally in human plasma, urine, and saliva. It binds copper ions and has been studied for its signaling role in tissue repair, skin maintenance, and anti-inflammatory response modulation. GHK-Cu levels in the body decline with age, from approximately 200 ng/mL in young adults to much lower levels in older adults.
The research literature on GHK-Cu is extensive in the context of skin biology and wound healing. Studies have examined its effects on collagen synthesis, fibroblast activity, and a range of gene expression changes associated with tissue maintenance. Work by Dr. Loren Pickart, who first identified GHK in the 1970s, provides much of the foundational literature.
It is important to distinguish between GHK-Cu formulations. Topical copper peptide products are widely available in cosmetic skincare and have a different regulatory and safety profile from injectable GHK-Cu. Injectable GHK-Cu is Category-unclassified under current FDA compounding rules and requires a clinician-supervised evaluation through a program consultation rather than a direct peptide checkout.
Why do clinicians discuss sermorelin and GHK-Cu together?
The interest in combining sermorelin and GHK-Cu in protocols stems from their targeting of different aspects of tissue maintenance and repair:
- Sermorelin addresses the growth hormone axis and the systemic signals that regulate lean mass retention, sleep quality, and metabolic function.
- GHK-Cu addresses more localized tissue signaling, particularly in skin and connective tissue maintenance, through copper-dependent enzymatic pathways.
A patient interested in both growth hormone optimization and skin or connective tissue support might present goals that lead a clinician to consider both. The combination is not a standardized protocol with published clinical trial data specifically on the combination; it is an individualized clinical decision based on the patient’s specific goals, history, and what formulations are accessible to them.
There is no trial on this pairing — combining two peptides is an individualized clinical judgment, not a protocol you should self-assemble.
What is the regulatory difference between sermorelin and GHK-Cu access?
One practical consideration in any discussion of sermorelin and GHK-Cu together is that their access pathways are not the same.
Sermorelin is clinician-prescribed. It was the active ingredient in Geref, an FDA-approved drug discontinued in 2008, and it is compounded by licensed 503A pharmacies and FDA-registered facilities with a clinician prescription. You can read more about it and begin an assessment at PepScribe’s sermorelin page.
Injectable GHK-Cu has a separate regulatory history. It was removed from FDA’s Category 2 list in April 2026 after its nominations were withdrawn, and it is not in Category 1 or on the 503A Bulks List. Non-injectable GHK-Cu is a separate matter: FDA said it will be added back to Category 1 and intends to consult its Pharmacy Compounding Advisory Committee before the end of February 2027. Questions about injectable GHK-Cu belong in a clinician-supervised program consultation.
If you are interested in a protocol that includes GHK-Cu, the appropriate path is a clinician consultation where they can evaluate your individual situation and determine what is available and appropriate for you. The Longevity & Cellular Health program is the relevant PepScribe consultation pathway.
What to ask a clinician before starting
If you are researching a sermorelin and GHK-Cu stack, here are the questions worth asking in a clinician consultation:
- What baseline labs do you need before starting sermorelin — specifically IGF-1 and a growth hormone panel?
- Is injectable GHK-Cu accessible through your compounding pharmacy partner, and what is their source and sterility testing protocol?
- Are there any interactions with my current medications or health history that change the risk-benefit calculation for either peptide?
- What monitoring checkpoints do you use during a combined protocol?
A clinician who is not comfortable engaging with these questions specifically is not the right clinician for a peptide stacking protocol. The complexity warrants someone who has direct experience with growth hormone secretagogue protocols and is current on the regulatory landscape for Category-unclassified peptides.
Frequently asked questions
What is the sermorelin and GHK-Cu stack?
Stacking refers to using two or more peptides simultaneously as part of a clinician-supervised protocol. Sermorelin is a growth hormone-releasing hormone analog that stimulates the pituitary to release growth hormone. GHK-Cu (copper peptide) is a naturally occurring plasma tripeptide studied for tissue maintenance. They target distinct mechanisms, which is the rationale for combining them in some protocols.
Is sermorelin FDA-approved for compounding?
Sermorelin was the active ingredient in Geref, an FDA-approved drug discontinued in 2008 for reasons FDA determined in 2013 were not safety or effectiveness, and licensed 503A compounding pharmacies in the United States compound it with a clinician's prescription. It has a well-established clinical use history and is one of the most researched compoundable growth hormone secretagogues.
What is GHK-Cu used for clinically?
GHK-Cu (glycyl-L-histidyl-L-lysine copper) is studied in the literature for skin and connective tissue maintenance, wound healing support, and anti-inflammatory signaling. It is found naturally in human plasma and declines with age. Injectable GHK-Cu is Category-unclassified under current FDA compounding rules; topical formulations have different regulatory status.
Can you stack sermorelin with GHK-Cu?
This is a question for a prescribing clinician. Combination protocols depend on your individual health history, goals, current medications, and which formulations are accessible through your pharmacy. A clinician familiar with peptide therapy can assess whether a combination approach makes sense for your situation.
What are the access differences between sermorelin and GHK-Cu injectable?
Sermorelin is prescribed by licensed clinicians and compounded by licensed 503A pharmacies and FDA-registered facilities. Injectable GHK-Cu was removed from FDA Category 2 in April 2026 after its nominations were withdrawn, and it is not on the 503A Bulks List. Questions about injectable GHK-Cu belong in a clinician-supervised program consultation.
