Evidence-graded answer
Does GLP-1 cause dehydration?
Indirectly, yes — appetite suppression often reduces total fluid intake, and titration-week nausea/vomiting/diarrhea cause direct fluid losses. Acute kidney injury cases in surveillance data almost all trace back to severe dehydration.
Many patients stop noticing thirst as appetite drops. Setting a daily fluid target (2-3 L for most adults) and using a marked water bottle helps prevent gradual dehydration.
Watch for: dark concentrated urine, dizziness on standing, dry mouth, fatigue. These warrant fluid intake catch-up and, if vomiting persists, a call to the prescriber.
Electrolyte-balanced fluids (broth, oral rehydration salts) during illness or vomiting prevent the dehydration-AKI cascade.