Background Clenbuterol, while not classified as an anabolic-androgenic steroid (AAS), is commonly used alongside AAS for aesthetic purposes due to its thermogenic effects. Comparisons of its side effect profile relative to AAS remain limited. This study aimed to examine the side effects between participants classified as consuming either AAS and clenbuterol (clenbuterol group) or AAS without clenbuterol (AAS group).

Methods The sample (N = 1146) was drawn from the 2024 Global Drug Survey, and comprised solely males reporting either AAS only (n = 949), or AAS and clenbuterol (n = 197), in the previous 12 months. Binary logistic regression analyses assessed associations between use of compound type (clenbuterol group vs. AAS group) and four self-reported side effects: negative impact on heart, restlessness/irritability, irrational excitability, and rapid mood fluctuation. Age was included as a covariate in all models.

Results The clenbuterol group had significantly higher odds of reporting negative impacts on their heart (adjusted odds ratio [aOR] = 2.76, p < .001), rapid mood fluctuations (aOR = 1.73, p = .010), and irrational excitability (aOR = 1.61, p = .032) compared to the AAS group. Conversely, clenbuterol consumption was not a significant predictor of restlessness/irritability (aOR = 1.36, p = .122).

Conclusions Men consuming clenbuterol alongside AAS report higher rates of side effects than those consuming AAS alone. These findings underscore the need for targeted health promotion messaging regarding clenbuterol consumption for physique enhancement.