Weight Management
GLP-1 Side Effects: What Patients Should Know Before Starting
Nausea, diarrhea, and other gastrointestinal symptoms are the most common side effects of GLP-1 weight loss medications. Here is what the labels say and how a supervised program manages them.
Reviewed by the clinical team at Zest Regen Health · October 6, 2026 · 7 min read
Content managed by Phil Kim, Lucky Consulting Group
The most common side effects of GLP-1 weight loss medications are gastrointestinal: nausea, diarrhea, vomiting, constipation, and abdominal pain. These are prescription drugs, not lifestyle products, and the decision to start one should happen with a clinician who reviews your history, manages dosing, and monitors your response. At Zest Regen Health in Columbia, Maryland, GLP-1 support is offered within a medically supervised weight loss program, never as a self-directed purchase.
Which GLP-1 medications are we talking about?
The FDA-approved products most people mean by GLP-1 weight loss drugs are semaglutide (Wegovy) and tirzepatide (Zepbound). Both are injectable prescription medications for adults with obesity or overweight plus a weight-related condition, used together with diet and physical activity. They affect appetite signals and slow stomach emptying, which is a main reason digestive symptoms dominate the side effect lists on their labels.
The most common side effects
According to the FDA-approved prescribing information, the side effects reported by at least 5 percent of people taking these medications are gastrointestinal: nausea, diarrhea, vomiting, constipation, and abdominal pain, along with indigestion and burping. Headache, fatigue, dizziness, and injection-site reactions also appear on the labels. Gastrointestinal symptoms are often most noticeable when the dose increases, and they frequently lessen over time as the body adjusts.
| Side effect | How it is commonly managed |
|---|---|
| Nausea | Most common; gradual dose increases and smaller meals help |
| Diarrhea, vomiting, constipation | Hydration and diet adjustments; report persistent symptoms |
| Injection-site reactions | Mild redness or discomfort at the injection site |
| Headache, fatigue, dizziness | Reported on the labels; tell your clinician if persistent |
The boxed warning: what it is
Both Wegovy and Zepbound carry a boxed warning about thyroid C-cell tumors, based on findings in rodent studies. Because of this, neither medication should be used by anyone with a personal or family history of medullary thyroid carcinoma or with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). This is one reason a medical history review is required before prescribing, not a formality.
Other warnings on the labels
- Acute pancreatitis: seek care for severe abdominal pain that does not go away
- Gallbladder disease: gallstones and gallbladder inflammation have been reported
- Kidney injury: severe vomiting or diarrhea can cause dehydration, so hydration matters
- Severe allergic reactions: rare, and require immediate medical attention
- A history of pancreatitis, severe stomach emptying problems, or certain kidney conditions changes the risk discussion
What changed on the labels recently
In January 2026, the FDA asked manufacturers to remove the warnings about suicidal thoughts and behavior from GLP-1 medication labels after a comprehensive review, including a meta-analysis of placebo-controlled trials, found no increased risk. The FDA still advises monitoring mental health during treatment. In December 2025, the FDA approved a once-daily oral form of semaglutide for weight management, adding an option beyond injectables.
Why medical supervision matters
Side effects are common, but they are also manageable in a structured program: starting at the low end of the dosing range, increasing gradually only when tolerated, counseling on meal size and hydration, and checking in with follow-up visits and labs. A program that hands you a vial and never follows up cannot do any of that. The practical difference is being treated as a patient rather than a customer.
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Sources & further reading
- Wegovy prescribing information (Novo Nordisk)
- Zepbound prescribing information (Eli Lilly)
- FDA: FDA requests removal of suicidal behavior and ideation warning from GLP-1 RA medications (January 2026)
- FDA: FDA's concerns with unapproved GLP-1 drugs used for weight loss
- FDA: FDA approves new medication for chronic weight management (Zepbound)
Next step
If you are considering a GLP-1 medication, the first step is a medical evaluation, not a prescription. Book a free 15-minute consultation at the Columbia clinic to review your history, discuss candidacy and risks, and see whether a supervised GLP-1 program fits your goals.
Talk with our care team about this topic
A member of our clinical team can answer your questions at the Columbia, Maryland clinic. If GLP-1 Weight Loss Programs may be appropriate for you, the first step is a consultation.
Care at Zest Regen Health is physician-guided. Meet our physicians, who evaluate patients at the Columbia, Maryland clinic.