Is Tesamorelin safe? What do clinical trials show

Clinical trials generally indicate that tesamorelin is relatively safe and well-tolerated when used under appropriate medical supervision, although it can cause adverse effects, increase IGF-1 levels, and may not be suitable for individuals with certain medical conditions [1–11].

Clinical trials have consistently shown that tesamorelin effectively reduces visceral abdominal fat whilst maintaining an acceptable safety profile. In a randomised, placebo-controlled trial conducted by Falutz et al. (2007), tesamorelin reduced visceral fat by approximately 15% over 26 weeks without a significant deterioration in fasting glucose levels or insulin regulation [1]. Similar results were reported in the pooled Phase III studies conducted by Falutz et al. (2010), where tesamorelin continued to reduce abdominal fat and improve lipid markers, whilst remaining generally well tolerated [2]. Long-term extension studies also demonstrated that continuing tesamorelin therapy for up to 52 weeks maintained the benefits without the emergence of new serious safety concerns during treatment [3].

Research into HIV-associated non-alcoholic fatty liver disease (NAFLD) has also shown encouraging safety outcomes. Stanley et al. (2019) found that tesamorelin significantly reduced liver fat over 12 months with no significant difference in fasting glucose or HbA1c compared to placebo [4]. HbA1c is a blood test reflecting average blood sugar levels over several months. Fourman et al. (2020) further reported improvements in liver mitochondrial function and inflammatory pathways, without evidence of liver toxicity [5]. These findings are relevant as tesamorelin works via the growth hormone (GH) and insulin-like growth factor-1 (IGF-1) pathway, which can impact metabolism and cell growth signalling.

The most frequently reported adverse reactions to tesamorelin in clinical trials included:

• Injection site reactions
• Joint pain (arthralgia)
• muscle pain (myalgia)
• Mild swelling or water retention
• peripheral swelling (fluid accumulation in tissues)
• tingling or numbness (paresthesia)
• mild hypersensitivity reactions or allergic reactions [1–4,6,7]

The majority of adverse events were described as mild to moderate, rather than severe. Injection site irritation was among the most common complaints, as tesamorelin is administered daily via subcutaneous injection, meaning an injection into the fatty tissue just under the skin [1–3].

Tesamorelin can significantly increase IGF-1 levels, which is a major part of the drug's mechanism of action. Numerous clinical studies have consistently demonstrated elevated IGF-1 levels during treatment [1,2,8]. As persistently high IGF-1 levels can theoretically impact pathways related to cancer or metabolic regulation, regular monitoring of IGF-1 levels is often recommended during therapy.

The effect on blood sugar levels was also thoroughly investigated during tesamorelin treatment. Most studies showed generally stable fasting glucose levels and HbA1c, although some participants experienced slight increases in glucose-related markers [4,6,9]. Rahman et al. (2023) observed a mild increase in HbA1c in some participant groups during further analyses of phase III studies, however, the changes were typically minor [6]. Current evidence suggests that tesamorelin may have a more favourable glycaemic profile than direct growth hormone therapy, as it stimulates the body's natural pulsatile GH secretion instead of continuous exogenous growth hormone delivery.

Some individuals may not be suitable candidates for tesamorelin therapy. Typical contraindications and precautions include:

• active malignant disease
• Pregnancy
• known allergy or hypersensitivity to tesamorelin or its ingredients
• significant hypothalamic-pituitary disorders
• Pituitary tumours or previous pituitary surgery
• severe uncontrolled endocrine disorders [10]

Extra caution is often recommended for individuals with risk factors for diabetes, glucose intolerance, or a history of cancer, as tesamorelin affects GH and IGF-1 signalling pathways [10].

Long-term safety data for tesamorelin remain relatively promising, although studies beyond its use in HIV-related conditions are still somewhat limited. Falutz et al. (2008) demonstrated sustained reductions in visceral fat for 52 weeks with generally acceptable tolerability [3]. A more recent meta-analysis by Badran et al. (2026), encompassing randomised controlled trials, found that tesamorelin improved body composition, reduced liver fat, and increased lean body mass without causing severe adverse events or significant glucose metabolism disturbances [11]. However, the researchers noted a higher incidence of joint pain, muscle pain, paraesthesia, and injection site reactions compared to placebo.

Generally speaking, current clinical evidence suggests that tesamorelin is typically safe when prescribed and monitored appropriately by a medical professional, especially in the context of visceral fat accumulation associated with HIV and fatty liver disease. However, as tesamorelin affects hormonal pathways related to GH and IGF-1, thorough screening, monitoring, and individual medical assessment remain important throughout treatment.

Disclaimer

The content is for educational and informational purposes only and should not be interpreted as medical advice, diagnosis, or treatment recommendation. Tesamorelin is a prescription medication that affects hormonal pathways and may not be suitable for everyone. Tesamorelin should only be used under the supervision of a qualified healthcare professional with appropriate metabolic and endocrine health monitoring.

References

1. Falutz J, Allas, S., Blot, K., et al. (2007). Metabolic effects of a growth hormone-releasing factor in patients with HIV. The New England Journal of Medicine, 357(23), 2359–2370. https://doi.org/10.1056/NEJMoa072375
2. Falutz J, Mamputu, J. C., Potvin, D., et al. (2010). Effects of tesamorelin (TH9507), a growth hormone-releasing factor analogue, in human immunodeficiency virus-infected patients with excess abdominal fat: A pooled analysis of two multicentre, double-blind placebo-controlled phase 3 trials with safety extension data. The Journal of Clinical Endocrinology & Metabolism, 95(9), 4291–4304. https://doi.org/10.1210/jc.2010-0490
3. Falutz J, Allas, S., Mamputu, J. C., et al. (2008). Long-term safety and effects of tesamorelin, a growth hormone-releasing factor analogue, in HIV patients with abdominal fat accumulation. AIDS(14), 1719–1728. https://doi.org/10.1097/QAD.0b013e32830a5058
4. Stanley TL, Fourman, L. T., Feldpausch, M. N., et al. (2019). Effect of tesamorelin on non-alcoholic fatty liver disease in HIV-positive individuals: A randomised, double-blind, multicentre study. The Lancet HIV, 6(12), e821–e830. https://doi.org/10.1016/S2352-3018(19)30338-8
5. Fourman LT, Billingsley, J. M., Agyapong, G., et al. (2020). Effects of tesamorelin on hepatic transcriptomic signatures in HIV-associated NAFLD. JCI Insight, 5(16), e140134. https://doi.org/10.1172/jci.insight.140134
6. Rahman F, McLaughlin, T., Mesquita, P., et al. (2023) Effect of tesamorelin in people with HIV with and without dorsocervical fat: post hoc analysis of phase III double-blind placebo-controlled trial. Journal of Clinical and Translational Science, 7(1), e40. https://doi.org/10.1017/cts.2022.515
7. Russian SC, Ockene, M. W., Arpante, A. K., et al. (2024). Efficacy and safety of tesamorelin in people with HIV taking integrase inhibitors. AIDS, 38(12), 1758–1764. https://doi.org/10.1097/QAD.0000000000003965
8. Falutz J, Allas, S., Kotler, D., et al. (2005). Placebo-controlled dose-ranging study of a growth hormone-releasing factor in HIV-infected patients with abdominal fat accumulation. AIDS, 19(12), 1279–1287. https://doi.org/10.1097/01.aids.0000180099.35146.30
9. Baker LD, Barsness, S. M., Borson, S., et al. (2012). Effects of growth hormone-releasing hormone on cognitive function in adults with mild cognitive impairment and healthy older adults: Results of a controlled study. Archives of Neurology, 69(11), 1420–1429. https://doi.org/10.1001/archneurol.2012.1970
10. Tesamorelin. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. (2018). Tesamorelin. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases. Available at: NCBI Tesamorelin Overview
11. Badran AS, Helal, A., Shata, K. S., & Ayesh, H. (2026). Body composition, hepatic fat, metabolic, and safety outcomes of tesamorelin, a GHRH analogue, in HIV-associated lipodystrophy: A meta-analysis of randomised controlled trials. Obesity Research & Clinical Practice, 20(1), 2–12. https://doi.org/10.1016/j.orcp.2026.01.002