Taking a GLP-1? Here Are 5 Side Effects Nobody Warned You About
By Eddie Khoriaty, BPharm, R.Ph., C.Ph.
GLP-1 receptor agonists have transformed the way type 2 diabetes and obesity are managed. While most patients are informed about common side effects like nausea and appetite suppression, there are several lesser-known effects that often catch people off guard. As a pharmacist, I regularly field questions about these unexpected reactions.
Let’s take a look at five surprising effects of GLP-1 medications, and what you can do if they happen to you:
1. Food Aversions and Taste Changes
Many people expect to feel less hungry on GLP-1s, but what surprises them is the sudden aversion to specific foods. It's not uncommon for formerly beloved items like coffee, chicken, or eggs to suddenly seem unappetizing. Greasy or sugary foods are frequent culprits too.
This goes beyond appetite suppression; GLP-1s influence the gut-brain axis and may alter dopamine signaling, the pathway associated with reward and pleasure. When dopamine is disrupted, the brain stops associating food with satisfaction, which can explain those abrupt taste changes.
An example not related to GLP-1s would be, disulfiram – a drug that is given to alcoholics which makes them feel sick if they drink alcohol. It’s difficult to derive pleasure from a beer if halfway through you start to vomit, turn red, and your heart is beating a mile a minute. The bottom line is that when something takes the fun out of a particular activity, such as eating or drinking, it’s generally altering the release of dopamine which would usually accompany that activity.
If you notice your preferences shifting, it’s not all bad news. Use it as a chance to explore lighter, more nutrient-dense foods. Just ensure you're still hitting your protein goals and covering your nutritional bases with the right supplements.
2. Hair Shedding (Telogen Effluvium)
While hair loss is now formally recognized on newer GLP-1 labels, (such as Zepbound, where alopecia was reported in 4% to 5% of patients in clinical trials) it is a frequent topic of concern. In most cases, this shedding isn't caused directly by the medication itself, but rather by telogen effluvium: a temporary shift in the hair growth cycle triggered by rapid weight loss, caloric changes, and metabolic stress.
Maintaining adequate protein intake (about 0.8–1g per pound of ideal body weight) is essential. Nutrients like iron, B12, biotin, and zinc are also key to hair health. Lab work can help identify and address any deficiencies. A well-rounded supplement like GILA Renew can help fill in nutritional gaps, especially for those focusing on hair, skin and nail health during weight loss. I recommend getting your labs checked if shedding is significant or prolonged.
On a personal note, my wife and I struggled to meet our protein targets until we began meal prepping and using protein shakes. We prep a shake mix in the morning with protein powder, collagen, peanut butter, and almond milk - ready to go all day. It’s made a huge difference, and we’re always open to hearing your tips too.
3. Gallbladder Issues
One of the more serious but still under-discussed risks of GLP-1 use is the increased chance of developing gallstones or gallbladder inflammation. Rapid weight loss can cause cholesterol to collect in the bile and form stones, which may result in sharp abdominal pain or nausea.
To reduce your risk, aim for gradual weight loss (1–2 lbs. per week), stay well-hydrated, and don’t skip meals. If you experience upper right abdominal pain or nausea after eating, especially fatty meals, let your healthcare provider know right away.
4. Mood Changes and Brain Fog
Some patients report feeling emotionally flat, anxious, or mentally foggy on GLP-1 medications. Others say they feel more focused and calmer. The difference lies in how these medications affect serotonin and dopamine levels - the same neurotransmitters that regulate mood and cognition.
When starting on any new drug (including the GLP-1 class) pay attention to how you’re feeling mentally, not just physically. If you notice a shift in mood or mental clarity, don’t ignore it. Reach out to your provider. Sometimes a dosage adjustment or different medication can make all the difference.
5. Resting Heart Rate Changes (and Lightheadedness)
Here’s one most people don’t expect: GLP-1 medications actually tend to increase your baseline resting heart rate by a few beats per minute. However, patients often confuse this with low heart rate because they experience spells of dizziness, fatigue, or lightheadedness when standing up. This is usually caused by dehydration or sudden blood pressure drops rather than a slowing heart. Smartwatches are great for tracking these trends over time. If you notice persistent spikes in your resting heart rate, drops below 50 bpm, or feel symptomatic, it’s worth bringing up with your healthcare provider.
Final Thoughts
GLP-1 medications are powerful tools, I’m truly grateful to practice pharmacy at a time when we have access to treatments that can make such a difference. But with great tools comes the responsibility to use them wisely. It’s my job not just to dispense medications, but to help people understand how they work in the real world, not just in clinical trials.
We’re still learning about this class of drugs as more people use them, and more data becomes available. If you have questions, or if you’re curious about supplements that can support your health while on GLP-1 therapy, visit our Ask the Pharmacist page. I’m always here to help!
For more help managing treatment, visit our complete GLP-1 Resource Center.
Be well,
Pharmacist Eddie
Continue Learning About Metabolic Health
- When to Stop Losing Weight on GLP-1s
- How the Gila Monster Revolutionized Appetite Control
- What Are GLP-1 Medications? A Pharmacist's Guide
- How to Preserve Muscle While Losing Weight
← Explore the Metabolic Health Hub
Medical Disclaimer
The information provided in this article is intended for educational purposes only and should not be considered medical advice. It is not intended to diagnose, treat, cure, or prevent any disease, or to replace the advice of your physician or other qualified healthcare provider.
Always consult your healthcare provider before making changes to your diet, exercise routine, medications, or supplement regimen, especially if you have a medical condition, are pregnant or nursing, or take prescription medications.
Individual health needs vary, and the information presented may not be appropriate for every person.