Quick answer: the sermorelin side effects reported most often in clinical trials were temporary facial flushing and pain at the injection site.[1] Trials also found that most children developed antibodies to sermorelin, and one study saw fasting glucose and insulin rise.[3][4] Long-term safety in adults has not been studied.
This guide covers what the trials recorded, what anti-doping and medical reviewers flag, who should be cautious and what to ask a clinician. For the full background, see our sermorelin profile and the growth hormone peptides hub.
How sermorelin can cause side effects
Sermorelin is a short version of growth hormone-releasing hormone (GHRH). It prompts the pituitary gland to release growth hormone, which raises IGF-1.[1] Its side effects fall into three groups:
- Injection effects: reactions where the needle goes in.
- Hormone effects: results of more growth hormone and IGF-1, such as changes in blood sugar or fluid balance.
- Immune effects: the body making antibodies against the peptide.
Side effects reported in clinical trials
| Side effect | What was seen |
|---|---|
| Facial flushing | Most commonly reported effect, temporary[1] |
| Injection-site pain or irritation | Commonly reported; mild irritation in 3 of 40 children in one trial[1][3] |
| Antibodies to sermorelin | 39 of 40 children in a Shanghai trial[3] |
| Higher fasting glucose and insulin | Seen in a year-long UK study in children[4] |
| Higher blood phosphate | Seen in older men on twice-daily dosing[6] |
Flushing and injection-site pain
A 1999 drug review of the Geref program found that both single IV doses and repeated daily injections under the skin were well tolerated. Transient facial flushing and pain at the injection site were the most common adverse events.[1] For general tips on spotting a problem, see our guide to peptide injection-site reactions.
Pediatric trials
- Geref International Study: 110 children were treated nightly for up to a year. The authors reported no adverse changes in blood chemistry or hormones, no change in fasting glucose and no excessive IGF-1, and described treatment as well tolerated.[2]
- Radiation-induced deficiency: in 9 children in the UK, no adverse events attributable to sermorelin were seen over a year.[5]
- Shanghai randomized trial: no serious side effects were seen in 60 children, though 3 reported mild injection-site irritation.[3]
Studies in older men
- Two weeks of twice-daily injections: no effect on fasting glucose, blood pressure, or routine blood chemistry and blood counts. Blood phosphate rose.[6]
- Six weeks of 2 mg nightly: no significant adverse effects were observed in 11 men, and weight, glucose, insulin and lipids did not change.[7]
- A related analog: in a 16-week study of a modified GHRH fragment (not sermorelin itself), the only adverse effect was temporarily raised blood fats, which resolved by the end of the study.[8]
These studies were small, short and in healthy volunteers, so rare side effects would be missed.
Antibodies: the immune response to sermorelin
In the Shanghai trial, all 20 children on the higher dose and 19 of 20 on the lower dose developed antibodies against sermorelin.[3] The reassuring findings:
- Antibody levels did not track with how much children grew.
- No antibodies to growth hormone itself were detected.
- Antibodies had almost disappeared by 9 months after stopping.
Still, the same trial found IGF-1 rose at first and then fell back to pre-treatment levels, and growth was well below that seen on growth hormone.[3]
Blood sugar and metabolic effects
The evidence on blood sugar is mixed:
- In 18 London children with short stature given twice-daily injections for a year, fasting blood glucose and insulin both rose during therapy.[4]
- The Geref International Study found no change in fasting glucose.[2]
- In older men, two weeks of treatment did not change fasting glucose, and six weeks did not change glucose tolerance.[6][7]
The U.S. Anti-Doping Agency warns that growth hormone excess from sermorelin can contribute to insulin resistance and raise diabetes risk.[9] A 2026 endocrine review of growth hormone-axis peptides likewise listed dysglycemia (abnormal blood sugar), fluid retention, muscle and joint aches and injection-site reactions among the adverse effects clinicians see.[10] People with diabetes or prediabetes should discuss monitoring before starting.
Swelling, joint pain and long-term risks
USADA says users commonly report swelling and fluid build-up in the arms, legs and face, as well as joint and nerve pain. It also notes that chronic growth hormone excess is linked to high blood pressure and an enlarged heart.[9] These are known effects of too much growth hormone, but sermorelin trials have not measured how often they occur in adults using it for months or years.
A 2026 sports medicine review noted that for many unapproved peptides used in sports medicine, including sermorelin, rigorous human safety data are scarce.[12]
Product quality risks
FDA determined in 2013 that Geref was not withdrawn for safety or effectiveness reasons.[11] But today’s sermorelin is not Geref. USADA warns that black-market or unregulated sermorelin may be contaminated or mislabeled.[9] Side effects from a poorly made product may have nothing to do with sermorelin itself.
For more on product sources, see compounded vs research-grade peptides and our overview of peptide side effects.
Stopping sermorelin
In the London short-stature study, growth slowed below its pre-treatment rate during the first 3 months off therapy (catch-down growth), then returned to the old rate by 6 to 12 months.[4] No published study has followed adults after stopping.
Who should be cautious
The trials do not provide a formal list of people who should avoid sermorelin, because the official label is no longer published. Based on how it works and the findings above, discuss it carefully with a clinician if you:
- Have diabetes, prediabetes or insulin resistance.
- Have high blood pressure or heart disease.
- Have a history of cancer; a 2026 review flagged biologically plausible but unproven concerns that growth hormone-axis peptides could promote cell growth.[10]
- Are pregnant or breastfeeding, as no safety data exist.
- Compete in tested sport; sermorelin is prohibited and an exemption is highly unlikely.[9]
For dosing details, see our sermorelin dosage guide. For a side-by-side with a related peptide, see sermorelin vs ipamorelin.
Questions to ask a clinician
- Which side effects should make me stop and call you?
- Will you check fasting glucose, HbA1c and IGF-1 before and during treatment?
- Is there an FDA-approved alternative for my condition?
- Where is the product made, and how is its quality tested?
Report suspected side effects to your clinician and to FDA’s MedWatch program.
