Tesamorelin Side Effects: What the Research Reports
Hormonal, Growth Hormone & Body Composition Research
In the 26-week, placebo-controlled phase 3 trials of tesamorelin, which enrolled 806 adults with HIV and excess abdominal fat, the most common side effects were joint pain, redness and itching at the injection site, swelling in the legs and muscle aches (Egrifta FDA label, 2012). Most ran a few percentage points above placebo; joint pain, for example, was reported by 13.3% on tesamorelin against 11.0% on placebo. In the first of those trials, 412 patients, adverse events did not differ significantly between the two groups (Falutz et al., N Engl J Med, 2007). This page sets out what the trials recorded and what the longer studies add.
Findings
- In 543 tesamorelin and 263 placebo participants, the most frequent effects were joint pain (13.3% against 11.0%), injection-site redness (8.5% against 2.7%), injection-site itching (7.6% against 0.8%), leg swelling (6.1% against 2.3%) and muscle aches (5.5% against 1.9%).
- Effects such as swelling, joint pain and carpal tunnel symptoms are linked to the rise in growth hormone and were either transient or resolved when treatment stopped, according to the label.
- Pooled 52-week data found tesamorelin generally well tolerated, with no clinically meaningful changes in glucose at weeks 26 and 52 (Falutz et al., J Clin Endocrinol Metab, 2010).
- In a 12-month trial in 61 people with HIV and fatty liver, fasting glucose and HbA1c changes did not differ from placebo; injection-site complaints were more frequent but none was judged serious (Stanley et al., Lancet HIV, 2019).
View product →What is tesamorelin?
Tesamorelin is a synthetic analogue of growth hormone-releasing hormone (GHRH), the hypothalamic signal that tells the pituitary gland to release growth hormone. It is built on the full 44-amino-acid sequence of human GHRH (Falutz et al., 2010), with a small chemical change explained in Tesamorelin: One Small Change to a Natural Hormone. Because it works by raising the body’s own growth hormone, and in turn insulin-like growth factor 1 (IGF-1), most of its side effects follow from that rise. It is the active ingredient of Egrifta, approved in the United States in 2010 to reduce excess abdominal fat in adults with HIV-associated lipodystrophy. The efficacy record is covered in Tesamorelin and Visceral Fat: The Trial Record.
What did the phase 3 trials report?
Two multicentre, double-blind trials randomised 806 patients two to one to daily tesamorelin or placebo for 26 weeks, followed by a 26-week safety extension (Falutz et al., J Clin Endocrinol Metab, 2010). The label pools the adverse reactions from the first 26 weeks.
Common effects
| Effect | Tesamorelin | Placebo |
|---|---|---|
| Joint pain | 13.3% | 11.0% |
| Injection-site redness | 8.5% | 2.7% |
| Injection-site itching | 7.6% | 0.8% |
| Pain in arms or legs | 6.1% | 4.6% |
| Leg or ankle swelling | 6.1% | 2.3% |
| Muscle aches | 5.5% | 1.9% |
Source: Egrifta FDA label (2012), 26-week main phase, combined studies.
Effects linked to growth hormone
The label groups several effects under fluid retention, which it attributes to the induction of growth hormone release: swelling, joint pain and carpal tunnel syndrome (1.5% against 0%). Tingling (paresthesia, 4.8% against 2.3%) and reduced skin sensation (hypoesthesia, 4.2% against 1.5%) were also more frequent. These effects were either transient or resolved when treatment was stopped.
Injection-site reactions
Reactions at the injection site, including redness, itching, pain, irritation and bruising, occurred in 24.5% of tesamorelin participants and 14.4% of placebo participants during the first 26 weeks. Among those who continued for a further 26 weeks, the incidence was 6.1%.
Hypersensitivity and other effects
Hypersensitivity reactions, including itching, redness, flushing, hives and other rashes, occurred in 3.6% of tesamorelin participants. Nausea was close to placebo (4.4% against 3.8%), and vomiting was reported by 2.6% against none on placebo.
How many stopped?
In the 26-week main phase, 9.6% of tesamorelin participants and 6.8% of placebo participants stopped because of adverse reactions. Apart from hypersensitivity, the commonest reasons were growth hormone-related effects (4.2%) and injection-site reactions (4.6%). In the extension, 2.4% of those who stayed on tesamorelin stopped because of adverse events (Egrifta FDA label, 2012).
What happened to blood sugar and IGF-1?
Because growth hormone opposes some of insulin’s actions, glucose was a primary safety measure. Mean fasting glucose and fasting insulin did not differ significantly from placebo after 26 weeks. Mean HbA1c, a marker of average blood sugar over about three months, rose from 5.26% to 5.39% on tesamorelin against 5.28% on placebo, and 4.5% of tesamorelin participants reached an HbA1c of 6.5% or more against 1.3% on placebo (Egrifta FDA label, 2012). A 2014 trial in 50 patients found a small rise in fasting glucose at two weeks that was no longer significant over six months (Stanley et al., JAMA, 2014).
IGF-1 rose by 81% in the 2007 trial (Falutz et al., 2007). The label reports that 47.4% of participants had IGF-1 above two standard deviation scores at 26 weeks, and recommends monitoring IGF-1 during treatment.
What does the research show about longer-term use?
In the pooled 52-week analysis, the reduction in visceral fat was maintained in those who stayed on tesamorelin, treatment was generally well tolerated, and there were no clinically meaningful changes in glucose at weeks 26 or 52 (Falutz et al., 2010). The longest placebo-controlled study ran 12 months in 61 people with HIV and fatty liver: tesamorelin reduced liver fat by 37% relative to baseline, glucose and HbA1c changes did not differ between groups, and the extra injection-site complaints were not judged serious (Stanley et al., Lancet HIV, 2019). That trial is covered in Tesamorelin and Liver Fat.
Antibodies to tesamorelin were detected in 49.5% of participants after 26 weeks. Participants with and without antibodies had similar reductions in visceral fat and similar IGF-1 responses, so the antibodies did not appear to alter the effect (Egrifta FDA label, 2012).
How does it compare with growth hormone itself?
Tesamorelin raises growth hormone through the pituitary’s own release pattern rather than supplying it directly, which is the main difference researchers draw between the two. The comparison is set out in Tesamorelin vs HGH, and its relationship to other growth hormone peptides in CJC-1295 + Ipamorelin vs Tesamorelin.
Why research-grade quality and storage matter
Every Vistara Labs product is third-party tested, with certificates on the lab reports page. Tesamorelin is supplied as a lyophilised (freeze-dried) powder; handling before and after mixing is covered in How Long Does Tesamorelin Last? and the tesamorelin reconstitution guide. Orders ship from within Canada by Canada Post Xpresspost.
Tesamorelin is supplied for laboratory research use only. The human data above come from clinical trials carried out under medical supervision.
Frequently asked questions
What side effects did tesamorelin trials report most often?
In the 26-week phase 3 trials, the most common were joint pain (13.3% against 11.0% on placebo), injection-site redness (8.5% against 2.7%), injection-site itching (7.6% against 0.8%), leg swelling (6.1% against 2.3%) and muscle aches (5.5% against 1.9%).
Why does tesamorelin cause joint pain and swelling?
The label attributes swelling, joint pain and carpal tunnel symptoms to fluid retention linked to the rise in growth hormone. These effects were either transient or resolved when treatment stopped.
What did tesamorelin research show about blood sugar?
Mean fasting glucose and insulin did not differ from placebo at 26 weeks, and pooled 52-week data showed no clinically meaningful changes in glucose. Mean HbA1c rose slightly, from 5.26% to 5.39%, and 4.5% reached an HbA1c of 6.5% or more against 1.3% on placebo.
What did the longest tesamorelin trial report on safety?
In a 12-month placebo-controlled trial in 61 people with HIV and fatty liver, glucose and HbA1c changes did not differ between groups, and the extra injection-site complaints were not judged serious.
Where can I buy tesamorelin in Canada?
Vistara Labs supplies tesamorelin as a lyophilised vial for laboratory research, third-party tested and shipped from within Canada by Canada Post Xpresspost.
Product details from vistaralabs.ca, October 2026. Sources: Falutz J et al. Metabolic effects of a growth hormone-releasing factor in patients with HIV. N Engl J Med. 2007. PMID 18057338. Falutz J et al. Effects of tesamorelin (TH9507), a growth hormone-releasing factor analog, in HIV-infected patients with excess abdominal fat: a pooled analysis of two multicenter, double-blind placebo-controlled phase 3 trials with safety extension data. J Clin Endocrinol Metab. 2010. PMID 20554713. Stanley TL et al. Effect of tesamorelin on visceral fat and liver fat in HIV-infected patients with abdominal fat accumulation. JAMA. 2014. PMID 25038357. Stanley TL et al. Effects of tesamorelin on non-alcoholic fatty liver disease in HIV: a randomised, double-blind, multicentre trial. Lancet HIV. 2019. PMID 31611038. US Food and Drug Administration. Egrifta (tesamorelin for injection) prescribing information. 2012. FDA label.
More on this: Tesamorelin in Canada: A Researcher’s Buying Guide.
All products supplied by Vistara Labs are intended for laboratory research use only. They are not drugs, are not approved for human or veterinary use, and are not intended to diagnose, treat, cure or prevent any condition. Nothing on this page constitutes medical advice or guidance for use in humans.
References
Tesamorelin has been studied in randomised placebo-controlled trials measuring body composition and liver fat directly.
- Effects of tesamorelin, a growth hormone-releasing factor, in HIV-infected patients with abdominal fat accumulation: a randomized placebo-controlled trial with a safety extensionRandomised placebo-controlled trial with safety extension; 404 people with HIV-associated abdominal fat accumulation.
- Effects of tesamorelin on non-alcoholic fatty liver disease in HIV: a randomised, double-blind, multicentre trialRandomised, double-blind, multicentre trial in people with HIV and non-alcoholic fatty liver disease, 12 months.
Links open the study record on PubMed so the source can be checked directly. Listing a study is not a claim that its findings apply to any other use, product or route of administration. Research use only.
