Here's the short version. Sermorelin principally stimulates growth hormone release; that mechanism does not establish a testosterone benefit. The studies measured growth hormone and IGF-1. None of the controlled ones showed testosterone going up, and the one paper that did report a rise was in men who were already taking testosterone.
Is sermorelin testosterone, or a growth hormone?
Neither. Sermorelin is a copy of the first 29 amino acids of growth-hormone-releasing hormone, the signal that tells the pituitary to release growth hormone.
Think of it as a messenger one step up the chain. Growth hormone then prompts the liver to make IGF-1, which does much of growth hormone's work in the body. Testosterone runs on a different chain, from the pituitary to the testes. Pushing on one chain doesn't automatically move the other, and the cited studies do not establish a testosterone treatment effect.
Sermorelin was once an approved brand, Geref. FDA withdrew the approvals in 2009 at the maker's request and later said that wasn't for safety or effectiveness reasons [5]. Today it comes from compounding pharmacies.
Does sermorelin raise testosterone?
No controlled trial shows it does. The studies that gave sermorelin, or the same molecule, to older adults reported growth hormone and IGF-1, not a testosterone rise.
One 1992 study did touch on testosterone. Older men started with lower testosterone than young men, as you'd expect with age. The paper's summary doesn't report testosterone changing during treatment [1]. The six-week and 16-week studies don't report testosterone at all [2] [3].
| Study | Who | Growth hormone | IGF-1 | Testosterone |
|---|---|---|---|---|
| Corpas 1992 [1] | 10 older men, 14 days per dose level, GHRH 1-29 | Up at the higher amount | Up at the higher amount | Lower than young men at the start; no change reported |
| Vittone 1997 [2] | 11 healthy older men, 6 weeks, no placebo group | Night-time release up | No change | Not reported |
| Khorram 1997 [3] | 19 older men and women, 16 weeks, a close analog of GHRH 1-29 | Up | Up 28% | Not reported |
| Sigalos 2017 [4] (chart review) | 14 men on testosterone therapy, sermorelin plus two other peptides | Not measured | Up | Rose from about 90 days, but the men were already on testosterone |
None of these studies was a placebo-controlled trial of sermorelin's effect on testosterone.
What sermorelin does raise: growth hormone and IGF-1
In older adults it raised growth hormone, and in some studies IGF-1. The size of the effect varied a lot.
- Given twice a day for 14 days, the higher of two amounts brought growth hormone and IGF-1 in older men up to the levels of young men [1].
- A close analog of the same molecule raised IGF-1 by 28% in older men and women over 16 weeks [3].
- Given once at night for six weeks, it raised night-time growth hormone, but IGF-1 didn't change [2].
Whether higher IGF-1 builds muscle is its own question, covered in does sermorelin build muscle. For timing, see how long sermorelin takes to work.
The study sellers cite
A 2017 chart review of 14 men on testosterone, who took sermorelin with two other growth-hormone peptides, found IGF-1 rose. It can't show what sermorelin did on its own [4].
The men were 29 to 39 and had low testosterone. Their IGF-1 rose on the three-peptide mix. Testosterone and free testosterone also rose from about 90 days, according to the full paper [4].
That sounds like support until you look at the design. Every man was on testosterone therapy throughout. There was no comparison group, so a testosterone rise could reflect the therapy they were already taking, changes to it, or the other two peptides. Out of 105 charts reviewed, only 14 met the authors' rules for inclusion.
Does sermorelin increase estrogen?
The cited evidence does not establish that sermorelin raises estrogen. A PubMed search for sermorelin with estrogen or estradiol returned one paper: the chart review above. It found no significant change in estradiol at any follow-up [4].
That paper had one more wrinkle. Seven of the 14 men were on estrogen-blocking drugs at some point, and their IGF-1 rise trended smaller, though the difference fell short of statistical significance [4]. That's a fact about one small group, not a rule. Your prescriber can check hormone levels if estrogen is a concern.
What testosterone treatment is approved for
FDA-approved testosterone products are for men with low testosterone caused by an identifiable medical condition, confirmed by blood tests.
Labels list two kinds: primary hypogonadism, where the testes don't make enough, and hypogonadotropic hypogonadism, where the pituitary or hypothalamus doesn't send the signal. The diagnosis needs morning testosterone below the normal range on at least two separate days [6].
That's changing at the edges. Current labels still say safety and effectiveness in "age-related hypogonadism" haven't been established [6]. In June 2026, FDA asked makers to remove that line and revise the prostate safety information [7].
Part of FDA's reasoning was TRAVERSE, a trial of more than 5,200 men on a testosterone gel or placebo. Serious heart events were about the same in both groups: 7.0% against 7.3% [7]. Testosterone still carries real side effects, which is why it needs a diagnosis and follow-up labs. Sermorelin has no trial of that size for any outcome.
If low testosterone is what you're dealing with, start with what testosterone therapy is and the hormones shortlist.
Sermorelin with testosterone?
Whether to combine them is a prescriber's decision. No controlled trial has tested the pair. For how the two compare side by side, see sermorelin or testosterone.
If you're weighing sermorelin itself, see how to get sermorelin and what sermorelin costs. And if weight is part of the goal, does sermorelin help with weight loss covers that evidence.