South African healthcare professionals and patients are increasingly taking note of a growing body of research suggesting that GLP-1 medications like Ozempic, Wegovy, and Mounjaro may be causing side effects that have largely flown under the radar. While nausea, fatigue, constipation, and diarrhoea have long been recognised as common complaints among users of these weight-loss and diabetes drugs, a significant new study has uncovered a range of unexpected symptoms that weren’t previously well-documented in clinical settings.
The research, published in Nature Health, represents one of the most comprehensive attempts to capture the real-world experiences of GLP-1 users by analysing over 410,000 Reddit posts mentioning semaglutide or tirzepatide. What researchers discovered was striking: among the 67,008 users who self-reported using these medications, 43.5% posted about experiencing at least one side effect. More intriguingly, the study highlighted several symptoms that have largely been dismissed or overlooked by mainstream medical discourse, including menstrual irregularities, chills, and hot flashes.
For South Africans considering or currently using these medications, the findings raise important questions about what we’re being told versus what patients are actually experiencing. As we reported earlier on SA Report, the rise of GLP-1 drugs has been meteoric, with demand far outstripping supply in many parts of the country. Yet our understanding of their full impact on the human body remains incomplete.
Dr Jeffrey Lee, a board-certified plastic surgeon based in Boston, offered SA Report valuable insights into why these hidden side effects might be occurring and what the medical community should understand about reports emerging from social media platforms. According to Lee, while gastrointestinal issues remain the most commonly observed side effects in clinical practice, the mechanism of action for GLP-1 medications extends far beyond the digestive system.
Understanding the hidden side effects of GLP-1 drugs
The crux of the matter lies in how GLP-1 agonists work on multiple systems within the body simultaneously. These drugs don’t simply suppress appetite in the stomach—they act directly on the hypothalamus, the part of the brain that regulates temperature, hormones, and numerous core bodily functions. This broader systemic action explains why some patients report experiencing symptoms that seem entirely unrelated to weight loss or blood sugar management.
Lee acknowledged that whilst gastrointestinal complaints like nausea and bloating are typically temporary and dose-dependent, the lesser-known side effects highlighted in the Reddit study merit serious consideration. However, he stressed an important caveat: many of these symptoms haven’t yet been well-established clinically, and researchers simply don’t have enough evidence to confirm whether they’re directly caused by the medication or influenced by secondary factors such as rapid weight loss, metabolic changes, or individual variations in physiology.
One particularly fascinating finding from Lee’s clinical experience relates to how GLP-1 drugs may dampen the brain’s reward response system. Reports have emerged of patients with alcohol dependency experiencing decreased urges to drink whilst taking these medications, suggesting that the drugs blunt reward pathways in the brain. Whilst this mechanism could prove beneficial in certain contexts—helping patients break harmful habits—it may also translate into a flattening of emotional experiences, which some users interpret as apathy or reduced libido.
Patient behaviour plays a critical role in determining which side effects manifest and how severely they’re experienced. Lee explained that individuals who restrict their caloric intake beyond what the medication is already suppressing may experience irritability and mood swings, whilst those who rely entirely on the medication’s appetite-suppressing effects might notice fewer emotional fluctuations altogether. This interplay between medication and behaviour is crucial for understanding the full picture of GLP-1 side effects.
The challenge facing medical professionals and patients alike is that social media platforms like Reddit capture anecdotal, self-reported experiences entirely devoid of clinical context. Without knowing whether a patient is taking other medications, has underlying health conditions, or is engaging in extreme dietary restriction, it becomes nearly impossible to determine causality. A symptom might appear to be caused by the GLP-1 drug when it’s actually the result of rapid weight loss, drug interactions, or other confounding factors.
Lee was forthright about the limitations inherent in using Reddit data for medical research. Self-reported data from social platforms introduces significant bias, as it typically captures only a narrow, more vocal subset of users. Those experiencing severe side effects are more likely to post about their experiences than those having positive outcomes, skewing the overall picture. Furthermore, the Reddit demographic may not adequately represent the broader population using these medications in terms of age, gender, medical history, or dosage patterns.
Despite these limitations, Lee argued that studies like the Nature Health research can serve a valuable purpose as an early warning signal. They generate hypotheses that can guide more rigorous, controlled clinical trials—the gold standard for drawing definitive medical conclusions. As these drugs become increasingly prevalent across South Africa and the world, the need for well-designed, prospective studies examining their full range of effects grows ever more urgent. Until then, patients and healthcare providers must remain vigilant, communicate openly about unexpected symptoms, and approach social media claims with appropriate scepticism while remaining open to possibilities that formal medical research may not yet have fully explored.