Important: This page is for educational purposes only. Do not stop any medication without consulting your doctor. If you have experienced vision changes while on a GLP-1 drug, seek immediate ophthalmologic evaluation.
NAION: The Vision Loss Side Effect (Now Subject of Lawsuit)
Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION) is the most serious newly identified side effect of GLP-1 drugs. A 2024 Harvard study found a 4–7x elevated risk in GLP-1 users. NAION causes sudden, often permanent vision loss and is the basis of MDL 3163.
Symptoms: Sudden painless vision loss in one eye upon waking, altitudinal visual field defect, loss of color vision.
If you experienced NAION after taking a GLP-1 drug, you may qualify for a lawsuit.
Common GLP-1 Side Effects (Labeled)
These side effects are listed on current drug labels and are well-established:
Gastrointestinal (Most Common)
- Nausea — very common, especially during dose escalation (affects 40–50% of users)
- Vomiting — common, particularly in early treatment phases
- Diarrhea — common, usually transient
- Constipation — common, especially with weight-loss doses
- Abdominal pain — cramping, bloating, gastroparesis symptoms
- GERD / acid reflux — worsened gastroesophageal reflux
- Gastroparesis (delayed gastric emptying) — can cause severe complications
Metabolic / Endocrine
- Hypoglycemia — low blood sugar, especially when combined with insulin or sulfonylureas
- Diabetic retinopathy complications — labeled warning; rapid improvement in blood sugar can temporarily worsen diabetic eye disease
- Thyroid C-cell tumors — black box warning; rodent studies showed increased risk (clinical significance uncertain)
Cardiovascular
- Increased heart rate — tachycardia reported in clinical trials
- Blood pressure changes — usually decrease; abrupt changes may affect optic nerve perfusion
Renal / Kidney
- Acute kidney injury — linked to dehydration from GI side effects; labeled warning
Pancreatitis
- Acute pancreatitis — labeled warning; patients with history of pancreatitis should use caution
Unlabeled / Emerging Side Effects
These side effects have been identified in research or adverse event reports but have not been added to US drug labels:
Eye / Vision
- NAION — Harvard study (July 2024): 4.28x elevated risk in diabetes patients; 7.64x in obesity patients. NOT on US label as of March 2026.
- Other vision changes — blurred vision, visual field abnormalities reported in post-market data
Neurological / Psychiatric
- "Ozempic brain" — colloquial term for cognitive fog, reduced mental sharpness reported anecdotally by users
- Suicidal ideation — FDA issued a safety communication (2023) requiring further study; preliminary evidence inconclusive
- Anesthesia complications — aspiration risk during general anesthesia due to delayed gastric emptying; FDA guidance updated 2023
Musculoskeletal
- "Ozempic face" / muscle loss — facial wasting and lean muscle mass reduction from rapid weight loss; not a drug-specific effect but weight-loss-related
- Bone density — potential for decreased bone mineral density with significant weight loss
GLP-1 Side Effects by Drug
| Side Effect | Ozempic | Wegovy | Mounjaro | Trulicity |
|---|---|---|---|---|
| Nausea | ✓ | ✓✓ | ✓✓ | ✓ |
| NAION risk (Harvard) | 4.28x | 7.64x | Under study | Under study |
| Pancreatitis | Labeled | Labeled | Labeled | Labeled |
| Gastroparesis | Reported | Reported | Reported | Reported |
| Thyroid C-cell (black box) | Yes | Yes | Yes | Yes |
What to Do If You Experienced Side Effects
- Vision changes: Seek immediate ophthalmologic evaluation. Discontinue GLP-1 drug only per your doctor's guidance.
- Severe GI symptoms: Contact your prescribing physician. Serious gastroparesis may require hospitalization.
- Report to FDA: File a MedWatch report at fda.gov/safety/medwatch
- Legal options: If you were diagnosed with NAION, use our eligibility checker to explore your legal options.