What Beauty Editors Should Know About GLP-1 Side Effects

When clients mention starting a new medication for weight loss, most beauty professionals think of nausea or digestive complaints. But as GLP-1 drugs—semaglutide (Ozempic, Wegovy, Rybelsus) and tirzepatide (Mounjaro, Zepbound)—become increasingly common, a new Nature Health study reveals that the side effects affecting appearance and confidence extend far beyond the expected gastrointestinal issues. Researchers who analyzed 400,000 Reddit posts over five years found an array of symptoms that patients experience but rarely discuss with their providers, let alone mention at their next salon appointment.

What the Study Uncovered

The AI-driven analysis identified posts from 67,008 GLP-1 users describing both well-documented side effects and surprising ones. While nausea, vomiting, constipation, and diarrhea remain the most commonly reported complaints, the research surfaced symptoms that don’t typically appear on medication labels: fatigue, menstrual irregularities, chills, and hot flashes. Other studies have linked GLP-1 use to hair loss and nail changes, suggesting the official list of known side effects will likely expand as more people take these medications.

The Known and Lesser-Known Effects

The study confirmed that gastrointestinal discomfort is still the dominant concern among users, typically appearing when starting the medication or increasing the dose. However, the researchers were careful to note that the link between GLP-1 use and the surprising side effects—menstrual changes, fatigue, chills, and hot flashes—was correlational, not necessarily causal. Some of these symptoms may stem from rapid weight loss itself rather than the drug directly, a distinction that matters when advising clients or colleagues.

The Gray Market Problem

An added complication: increasing numbers of people obtain GLP-1s outside standard medical channels and often follow more aggressive dosing schedules than prescribed, potentially increasing the risk of side effects. This lack of medical oversight means patients may not receive proper counseling about what to expect or how to manage symptoms effectively.

How Weight Loss Triggers These Changes

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Understanding why these side effects occur requires knowing what happens inside the body during rapid weight loss. Dr. Mir Ali, medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA, explains that beyond fat loss, significant hormonal shifts take place. Women typically experience drops in circulating estrogen levels, while men’s testosterone often increases. These hormone changes can account for some of the unexpected symptoms patients report.

The scale of weight loss is dramatic: patients using GLP-1s can shed up to 20% of their body weight over 72 weeks. This rate of change means the body has to adjust rapidly to a new diet, a new activity level, and fundamentally different hormone levels all at once.

Menstrual and Hormonal Side Effects

Among the lesser-known side effects, menstrual changes made the most sense to healthcare providers interviewed for this research. Kelley Gregorovic, MS, a board-certified family nurse practitioner at Tufts Medicine Weight and Wellness Center, notes that FDA adverse event reports have documented heavier-than-usual bleeding, blood clots, and bleeding between periods in some patients. These changes don’t prove the medication caused them, but they do warrant attention.

Weight Loss and Cycle Regularity

The relationship between rapid weight loss and menstruation is complex. For patients with PCOS or PCOS-related symptoms, weight loss can actually improve period regularity as insulin resistance and obesity improve. Conversely, rapid weight loss or insufficient calorie intake can disrupt cycles entirely. Rutuja Patel, DO, medical director of medical weight management at Northwestern Medicine Central DuPage Hospital, emphasizes that the speed and aggressiveness of weight loss matters significantly.

The Perimenopause Complication

Many women starting GLP-1s are in their 40s and 50s—an age range where perimenopause itself causes menstrual changes. Gregorovic points out that when a woman in midlife begins a GLP-1 and her periods change, attributing the shift solely to the medication ignores the fact that her weight, metabolic health, and hormones are all changing simultaneously. This overlap makes it genuinely difficult to isolate the medication’s specific role.

Fatigue and Nutritional Concerns

Fatigue emerged as one of the most commonly flagged symptoms in the study. Dr. Ali attributes much of this to the dramatic dietary shift and weight loss that accompany GLP-1 use, noting that energy typically improves once patients stabilize at a new weight and establish consistent eating and exercise routines. However, Gregorovic approaches fatigue as a detective would—asking whether patients are eating enough total calories, getting sufficient protein, staying hydrated, losing weight too rapidly, or losing muscle mass alongside fat.

If those factors check out, she digs deeper with blood work to identify potential anemia, nutritional deficiencies, or thyroid dysfunction. Appetite suppression from GLP-1s can sometimes become so severe that patients inadvertently under-eat, creating or worsening fatigue. This is especially relevant for beauty professionals who interact with clients regularly and may notice energy or appearance changes that warrant a conversation.

Temperature Sensitivity and Other Effects

Hot flashes and chills were flagged in the study but appear less common than other side effects. Both Dr. Ali and Dr. Patel described these as relatively infrequent complaints in their practices. When they do occur, one mechanism may be straightforward: the loss of body fat reduces natural insulation, making patients feel cold more easily. Adequate nutrition becomes crucial here as well, since the body needs sufficient nutrients to regulate temperature effectively.

When Clients Should Contact Their Doctor

The takeaway from the research is that healthcare communication matters. Gastrointestinal side effects—nausea, constipation, diarrhea, vomiting—remain the most common and are typically managed through dietary adjustments. These tend to resolve with time. Appetite suppression that feels excessive warrants a conversation with the prescribing doctor about nutrient levels and the appropriateness of current weight loss speed.

Any new symptom deserves attention, especially if it’s persistent or disruptive to daily life. A symptom that appears and disappears may be unrelated to the medication, but if it’s affecting work, sleep, confidence, or appearance—or if it persists beyond one or two cycles in the case of menstrual changes—patients should involve their doctor and, when relevant, a gynecologist. Dr. Patel emphasizes that when patients repeatedly report a change coinciding with starting GLP-1s, that report deserves investigation, even if the medication doesn’t ultimately turn out to be the cause.

For beauty professionals, the practical takeaway is simple: clients on GLP-1s are experiencing more than the nausea and digestive issues that dominate public discussion. Being aware of the full spectrum of potential side effects allows for more informed conversations and may help clients feel less alone in what they’re experiencing.