Sermorelin and HGH are often sold as two routes to the same place, higher growth hormone, but they act at different points in the same chain of signals and carry very different legal and evidence records. This page follows each from the point where it acts to what trials measured.
Two different points in one chain
The hypothalamus releases growth-hormone-releasing hormone (GHRH), the pituitary answers by releasing growth hormone, and growth hormone drives the liver to make IGF-1. Sermorelin is the first 29 amino acids of GHRH, the shortest synthetic fragment with the full activity of the natural hormone, and it acts on the pituitary to release growth hormone [1]. The other peptides that act on this chain, including the ghrelin mimetics, are compared in growth hormone peptides.
HGH in a prescription is somatropin, recombinant human growth hormone [3]. It is the end product, injected directly, so it does not depend on the pituitary at all.
That difference decides who each can help. Sermorelin needs a pituitary able to respond, which is why one approved form was a test of whether the pituitary could secrete growth hormone at all [2]. Somatropin works whether or not the gland responds, which is why its label covers adults whose growth hormone deficiency began in childhood or in adult life.
| Sermorelin | HGH (somatropin) | |
|---|---|---|
| What it is | A 29-amino-acid fragment of GHRH | Recombinant growth hormone |
| Where it acts | The pituitary, which then releases growth hormone | Directly, with no pituitary step |
| Approved uses | Children with idiopathic GH deficiency; a pituitary test (both discontinued) | Several childhood growth disorders and adult GH deficiency |
| Current status | Compoundable: FDA found it was not withdrawn for safety or effectiveness | Approved brand products; distribution limited by statute |
| Head-to-head trial in adults | None | None |
Why one is compounded and the other is not
Sermorelin was approved as GEREF: a 0.05 mg ampule in 1990 for testing the pituitary, and 0.5 mg and 1.0 mg vials in 1997 for idiopathic growth hormone deficiency in children with growth failure [2]. Both were discontinued in 2008, and FDA withdrew the approvals effective June 18, 2009.
In a 2013 notice, FDA determined that neither product had been withdrawn for reasons of safety or effectiveness [2]. That finding underpins sermorelin’s compounding status today, and it is a statement about why the product left the market, not a new review of how well it works.
Somatropin is still sold as approved brand products. A current label lists pediatric growth failure from growth hormone deficiency, Prader-Willi syndrome, birth small for gestational age, Turner syndrome and idiopathic short stature, plus adult growth hormone deficiency of either childhood or adult onset [3].
The one comparison that exists: growth in children
No trial has randomized adults to sermorelin or HGH. The nearest comparison comes from children with idiopathic growth hormone deficiency, and even there a 1999 review states that the recommended sermorelin dosage had not been directly compared with somatropin [1].
Across separate studies, the same review found that increases in height velocity with subcutaneous sermorelin at 30 micrograms per kilogram a day were smaller than with once-daily somatropin at 30 micrograms per kilogram. Once-daily sermorelin at bedtime did produce catch-up growth in most of the children treated, sustained over 12 months.
What each did in healthy older adults
The sermorelin record in older adults is small. In one study, 11 healthy men aged 64 to 76 with low IGF-1 injected 2 mg of GHRH each night for 6 weeks [5]. Nighttime growth hormone release rose, but IGF-1 did not change, and neither did muscle or fat measured by DEXA scan.
Two of six strength measures improved in that study, with no significant adverse effects. The authors concluded that single nightly doses were less effective than multiple daily doses at producing growth hormone or IGF-1 effects. What the rest of the sermorelin record shows is covered in does sermorelin work.
HGH has a larger record, pooled in a 2007 systematic review of randomized trials in healthy adults with a mean age of 69 [6]. It covered 220 people who received GH, at a mean starting dose of 14 micrograms per kilogram a day for a mean of 27 weeks.
+2.1 kg
lean body mass with GH vs no GH in healthy older adults (95% CI 1.3 to 2.9)
Liu 2007
−2.1 kg
fat mass with GH vs no GH (95% CI −2.8 to −1.35)
Liu 2007
0.1 kg
change in body weight, not significant (P = 0.87)
Liu 2007
Those body-composition changes came with side effects. People given GH were significantly more likely to have soft-tissue swelling, joint pain, carpal tunnel syndrome and breast enlargement, and somewhat more likely to develop diabetes or impaired fasting glucose [6]. The review concluded that GH cannot be recommended as an antiaging therapy.
In young, fit adults, a 2008 review of 303 people given GH found the same 2.1 kg gain in lean mass, but strength and exercise capacity did not appear to improve [7]. Swelling and fatigue were more common with GH.
The somatropin label lists fluid retention, including swelling, joint pain and carpal tunnel syndrome, as frequent, especially in adults [3]. Its warnings also cover glucose intolerance and diabetes, and it is contraindicated in active cancer.
What this means for a patient
The trade-off is between a direct hormone with a measurable effect and a documented side-effect profile, and an indirect signal whose effect depends on the pituitary and whose adult evidence is thin. Whether sermorelin's effect in adults is smaller, larger or simply different is unknown, because no adult trial has measured the two side by side.
What sermorelin trials actually used is set out in sermorelin dosage. Its closest relative with an active approval is covered in tesamorelin vs sermorelin.
The Strut Health review covers one seller that prescribes sermorelin for sleep and recovery. For sleep options with human studies behind them, start at the sleep goal page.