Propranolol and weight gain
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Propranolol and Weight Gain: Clinical and Experimental Evidence
Propranolol and Weight Gain in Adults
Several studies and case reports have found that propranolol, a non-selective beta-blocker, can be associated with weight gain in adults. Long-term use of propranolol after myocardial infarction led to a sustained increase in body weight compared to placebo, with an average difference of about 1.2 kg after one year, and this effect persisted over several years regardless of age or sex . Case reports have also described rapid and significant weight gain, even with short-term, low-dose propranolol, sometimes accompanied by increased appetite and overeating 14. These effects may be due to propranolol’s impact on metabolism, appetite, and possibly insulin resistance 145.
Mechanisms: Appetite, Metabolism, and Insulin Resistance
Propranolol may reduce the body’s thermogenic response to food and total energy consumption, which can contribute to weight gain . Experimental studies in animals have shown that propranolol can lead to increased weight, higher insulin levels, and a tendency toward higher blood glucose and free fatty acids, suggesting the development of insulin resistance and reduced fat breakdown . These metabolic changes may explain why propranolol is not ideal for patients who need to lose weight, such as those with high blood pressure .
Propranolol and Weight Gain in Special Populations
In children and infants, the evidence is less clear. One study in very low birth weight infants treated with propranolol for hemangiomas found that weight gain remained normal during treatment, suggesting that the drug does not necessarily cause weight gain in this population . However, in adults, especially those using propranolol for migraine prevention or psychiatric side effects, weight gain has been observed, though it is generally less pronounced than with some other medications like amitriptyline or divalproex sodium .
Propranolol, Thyroid Function, and Weight
Propranolol can affect thyroid hormone metabolism, particularly by reducing the conversion of thyroxine (T4) to triiodothyronine (T3). In hyperthyroid patients, this can halt weight loss and even lead to weight gain when T3 levels drop significantly . This effect is specific to patients with thyroid disorders and may not apply to the general population.
Weight Gain Not a Universal Side Effect
Despite these findings, increased appetite and weight gain are not commonly listed among the most noticeable side effects of propranolol, and some reviews suggest that these effects are relatively uncommon compared to other side effects like bradycardia or hypotension . Additionally, in some experimental settings, propranolol did not alter weight gain patterns in rats exposed to other metabolic challenges 69.
Conclusion
Propranolol is associated with weight gain in some adults, particularly with long-term use, and may increase appetite and alter metabolism, leading to increased body weight. The risk appears to be lower in children and infants, and not all patients experience this side effect. When prescribing propranolol, especially for patients concerned about weight, clinicians should monitor body weight and consider alternative medications if weight gain becomes problematic 13457.
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