Sermorelin side effects: what the Geref label and studies reported

The most common side effect of sermorelin is a reaction where the needle went in: pain, swelling or redness in about 1 patient in 6. Almost everything else on record was rare in the studies that counted it. The catch is who those studies enrolled. The numbers come mainly from children taking Geref, the discontinued brand, plus a few very small adult studies. We found no published safety data on adults using compounded sermorelin for months or years, and there is no current FDA label listing warnings, because there is no currently approved product.

A note on the main source. FDA’s website does not carry the full Geref label. The rates below come from a prescribing text reproduced by RxList, with an FDA revision date of October 2, 2001. It is unbranded, and its dose line conflicts with other sources, so we use it here for safety information only and treat it as a secondary copy.

Sermorelin side effect rates

The text gives no placebo comparison for these rates, and the largest trial behind them was open label. An event in the table happened during treatment. That does not prove the drug caused it.

The 1999 BioDrugs review gives a slightly different ranking, naming transient facial flushing and injection site pain as the most common adverse events. Part of the gap may be route. When sermorelin was given into a vein as a one-off diagnostic test, the Geref text lists flushing of the face, injection site pain, redness or swelling, nausea, headache, vomiting, altered taste, pallor and tightness in the chest.

What the smaller studies reported

Reassuring as that list looks, a study of 19 people cannot detect a problem that affects 1 person in 500. It also cannot detect something that takes years to appear.

When sermorelin side effects start and fade

No published study we found gives a timeline for sermorelin side effects. What exists is scattered. Injection reactions appear at the injection, by definition, and the Geref text does not say how long they last. The BioDrugs review calls the facial flushing transient. In Khorram 1997, high blood lipids came and went within the 16 weeks. Positive antibody tests often turned negative by the next check, according to the Geref text.

Thyroid changes behave differently, because they do not announce themselves at the injection. That is why the text relies on blood tests rather than symptoms.

What may help

The Geref text gives only a few practical instructions, and they are the ones a compounded user can actually apply:

• Rotate injection sites. The text recommends rotating them periodically. The injection sites guide shows the usual areas.
• Do not inject a cloudy solution or one with visible particles.
• Keep it clean. Wipe the vial stopper with an antiseptic before puncturing it, and use a sterile, disposable syringe and needle.
• Mix gently. The text says to swirl with a gentle rotary motion. The steps are in how to reconstitute.
• Follow the storage instructions. Geref vials were refrigerated, but the pharmacy’s label governs a compounded product.
• Use a puncture-resistant container for syringes and needles, and never reuse them.

We could not find a reputable clinical source for other tips, such as icing the site, so we have not listed any.

Thyroid, antibodies and lab changes

Thyroid. In the largest study, 8 of 110 children were already on thyroid replacement and 5 more started it during sermorelin treatment. The Geref text calls for thyroid hormone tests before and throughout treatment, and for replacement when indicated.

Antibodies. A large share of patients tested positive for anti-GRF antibodies at least once. The text says their meaning is unclear, that a positive test often turned negative at the next check, and that they did not appear to affect growth or link to a particular side effect.

Lab values. Blood levels of phosphorus, alkaline phosphatase, growth hormone and IGF-1 may rise. Phosphate rose in Corpas 1992 as well. A prescriber reading routine results should know you are on it.

Pituitary response. In Kirk 1994, overnight growth hormone levels and growth hormone responses to GHRH fell during a year of treatment, and growth slowed to 3.89 cm a year in the three months after stopping.

Does sermorelin cause cancer?

No study has shown that sermorelin causes cancer, and no study was designed to detect it. The Geref text says long-term animal studies for carcinogenicity and fertility were not performed. It does report no evidence of genetic toxicity to date.

The concern comes from the biology. Sermorelin raises growth hormone and IGF-1, and the label for its relative tesamorelin calls growth hormone a known growth factor, bars use in active cancer, and warns that the effects of prolonged high IGF-1 are unknown. That warning is written about tesamorelin, not sermorelin. Still, the same mechanism is why anyone with active cancer or a past cancer has a reason for caution here.

What tesamorelin’s label suggests to watch for

Tesamorelin works the same way and has a modern label built on hundreds of patients. Its warnings include fluid retention (swelling, joint pain, carpal tunnel syndrome), glucose intolerance and allergic reactions. Fluid retention did not appear in the Geref list, and the dose and population were different, so none of these can be read across as sermorelin rates. They do show what a careful prescriber might watch for, since no long adult sermorelin study has looked.

What we cannot tell you about compounded sermorelin

Everything above describes pharmaceutical Geref or study drug. A compounded vial is a different situation. HHS notes that FDA does not review compounded drugs for safety, effectiveness or quality before they are marketed. FDA’s 2024 ipamorelin briefing also found compounded vials combining sermorelin with ipamorelin, so a reaction may not come from sermorelin at all.

Products sold online “for research use only” sit further out still: 21 CFR 312.160 allows them only for laboratory animal or test-tube work, they are not legal to use on people, and none of the figures here says anything about what is in them.

Who should not use it, or should be careful

• Known sensitivity to sermorelin or any ingredient. This is the one contraindication in the Geref text.
• Active cancer or a past cancer, for the reasons above.
• Pregnancy. Pregnancy Category C: animal studies found minor variations in rat and rabbit fetuses at 3 and 6 times the human dose, and there are no adequate human studies. The text says use only if the potential benefit justifies the risk.
• Nursing. Whether sermorelin passes into breast milk is not known, and the text advises caution.
• Diabetes or prediabetes, because growth hormone works against insulin.
• Untreated hypothyroidism, which can jeopardize the response.
• Growth hormone deficiency caused by a lesion inside the skull. Such patients were not studied, and the text does not recommend treating them.
• Glucocorticoid treatment, which may inhibit the response.
• Kidney or liver disease. The text says no data are available.

The Geref text also says the recommended dose should not be exceeded. It gives no overdose data, and adults have no recommended dose at all, so see sermorelin dosage for what the studies used.

Red flags: when to get help

Get emergency help right away for signs of a serious allergic reaction:

• Trouble breathing
• Swelling of the face, mouth, lips or tongue
• Rash or hives

RxList’s drug summary also says to call 911 for sudden vision loss, blurred or tunnel vision, eye pain, or halos around lights; fast, irregular or pounding heartbeats, shortness of breath, or passing out; and severe headache, confusion, slurred speech, arm or leg weakness, or trouble walking.

Call the prescriber soon for:

• An injection site that stays painful, red or swollen
• High blood sugar readings, especially with diabetes or prediabetes
• New swelling, joint pain, or numbness in the hands, the fluid-retention signs named on the tesamorelin label
• Any new or returning cancer symptom
• A new pregnancy
• A thyroid test that has not been done or is overdue

Suspected side effects can be reported to FDA MedWatch at 1-800-FDA-1088. With a compounded product, tell the pharmacy that made it as well.