No, Delusional Thinking is Not an Established GLP-1 Side Effect
Delusional thinking is not a recognized or documented side effect of GLP-1 receptor agonists based on current clinical evidence, guidelines, and extensive safety data from randomized controlled trials. This appears to be misinformation rather than a legitimate medical concern.
What the Evidence Actually Shows
The most comprehensive and recent meta-analysis of 86 randomized controlled trials involving 133,378 participants found no association between GLP-1 receptor agonists and psychiatric disorders overall (RR 0.96; 95% CI 0.85-1.08) 1. This high-quality systematic review specifically examined multiple psychiatric outcomes and found no increased risk for:
- Depression (RR 0.88)
- Anxiety (RR 0.92)
- Bipolar disorder (RR 1.19)
- Delirium (RR 1.11)
- Schizophrenia (RR 1.45)
None of these categories include or suggest delusional thinking as a side effect 1.
Documented Side Effects from Guidelines
The actual common adverse effects of GLP-1 receptor agonists are gastrointestinal, not psychiatric 2:
- Nausea (occurs in ~25% of patients)
- Vomiting (up to 10%)
- Diarrhea (up to 10%)
- Dyspepsia
- Constipation
- Abdominal fullness
- Gallbladder disorders
- Cardiac arrhythmia/tachycardia (if symptomatic)
Emerging Psychiatric Research Context
While recent research has explored potential neuropsychiatric effects of GLP-1 receptor agonists, the focus has been on:
- Potential therapeutic benefits for substance use disorders, particularly alcohol use disorder 3, 4
- Possible neuroprotective effects and reduced dementia risk 4
- Mixed evidence on depression and anxiety (with conflicting results largely due to methodological limitations and confounding by indication) 4
Importantly, even in these exploratory studies examining psychiatric effects, delusional thinking or psychotic symptoms are not reported as adverse events.
The Single Case Report Caveat
One 2026 case report described dysphoria and aggression (not delusions) in a patient with underlying major depressive disorder who started tirzepatide 5. This isolated case does not establish causality and involved mood symptoms, not psychotic symptoms like delusions.
Clinical Bottom Line
If a patient on a GLP-1 receptor agonist develops delusional thinking, look for alternative explanations:
- Underlying psychiatric disorder
- Other medications
- Metabolic derangements (hypoglycemia, electrolyte abnormalities)
- Concurrent medical illness
- Substance use
The claim that GLP-1 receptor agonists cause delusional thinking lacks any credible scientific support and should be dismissed as misinformation.