Side effects of Tesamorelin: joint pain, water retention, and changes in blood sugar levels

The most commonly reported side effects of tesamorelin include injection site reactions, joint pain, muscle discomfort, mild fluid retention, swelling, and occasional changes in blood sugar regulation, although clinical trials have generally shown tesamorelin to be relatively well-tolerated by most participants [1–9]. Tesamorelin works by increasing the activity of natural growth hormone (GH) and insulin-like growth factor-1 (IGF-1), and it is thought that some adverse effects are related to increased stimulation of these hormonal pathways.

Joint pain is one of the more commonly reported adverse events in tesamorelin studies. Some participants experienced arthralgia, or joint pain, along with stiffness, muscle aches, or discomfort in the arms and legs [1,2,8]. These symptoms are similar to effects sometimes observed with therapies that increase GH and IGF-1 signaling. In most studies, joint-related adverse events were described as mild to moderate, not severe.

Water retention and mild swelling were also observed during tesamorelin treatment. Some individuals developed peripheral edema, which is the accumulation of fluids causing swelling in areas such as the hands, feet, or ankles [1,3,8]. Growth hormone signaling may affect sodium and water balance in tissues, which may contribute to temporary fluid retention in some individuals. Clinical studies generally considered these effects manageable and rarely required discontinuation of treatment.

Reactions at the injection site are among the most frequently reported side effects of tesamorelin. Redness, itching, irritation, mild pain, bruising, or swelling around the administration site have often been described in clinical trials [1–4]. Since tesamorelin is administered daily as a subcutaneous injection, meaning an injection into the fatty tissue under the skin, mild local skin reactions may occur during treatment.

Blood glucose levels and glucose metabolism were closely monitored in studies of tesamorelin because the GH and IGF-1 pathways can affect insulin sensitivity and glucose regulation. Most large clinical trials found that tesamorelin did not cause significant worsening of fasting glucose levels or HbA1c in most participants [2–7]. HbA1c is a blood test that reflects average blood sugar levels over several months. For example, Stanley et al. (2019) observed no significant differences in fasting glucose or HbA1c between the tesamorelin group and placebo during a 12-month study on HIV-associated nonalcoholic fatty liver disease (NAFLD) [5]. Similarly, the pooled phase III study by Falutz et al. (2010) demonstrated stable blood glucose control despite significant reductions in visceral fat and increases in IGF-1 levels [2].

However, some studies have observed slight increases in blood sugar markers in some participants. Rahman et al. (2023) reported mild increases in HbA1c in some responder and non-responder groups during additional analyses of phase III trials, although the changes were generally small [8]. Baker et al. (2012) also observed a slight increase in fasting insulin levels in older adults receiving tesamorelin during cognitive function studies, although values remained within normal physiological limits [9]. Because tesamorelin can increase IGF-1 levels and affect glucose metabolism, regular monitoring of blood sugar and IGF-1 levels is often recommended during treatment.

Other less frequently reported adverse events observed in trials of tesamorelin include:

• muscle pain (myalgia)
• tingling or numbness (paresthesia)
• nausea
• headache
• mild hypersensitivity reactions or allergic reactions
• Elevated IGF-1 levels
• Bruising or irritation at the injection site

Importantly, long-term clinical studies have generally shown tesamorelin to be relatively safe and well-tolerated when used under appropriate medical supervision [1–8]. Falutz et al. (2008) demonstrated sustained reductions in visceral fat over 52 weeks without significant worsening of glycemic control or major systemic toxicity [3]. A meta-analysis published by Badran et al. (2026) also showed that tesamorelin improved body composition and reduced liver fat without causing serious adverse events or major glycemic disturbances, although joint pain, muscle pain, tingling, and injection site reactions occurred more frequently than in the placebo group [10].

Because tesamorelin increases GH and IGF-1 activity, caution is generally advised in individuals with active cancer, uncontrolled diabetes, severe endocrine disorders, or significant metabolic instability. It is important to be monitored by a qualified healthcare professional during treatment.

Disclaimer

The content is for educational and scientific information purposes only and should not be interpreted as medical advice, diagnosis, or therapeutic recommendation. Tesamorelin is a prescription medication that may cause adverse effects and requires medical supervision, laboratory monitoring, and individual assessment by a qualified healthcare professional.