Can Vyvanse Cause Loose Stools?
Yes, Vyvanse (lisdexamfetamine) can cause diarrhea and loose stools as a documented adverse effect, occurring in approximately 7% of adult patients treated for ADHD—significantly higher than placebo (0%). 1
Evidence from FDA Drug Labeling
The official FDA prescribing information for Vyvanse clearly lists diarrhea as a common adverse reaction:
- In adults with ADHD: Diarrhea occurred in 7% of patients taking Vyvanse compared to 0% taking placebo in controlled 4-week trials 1
- In pediatric patients (ages 13-17): Gastrointestinal adverse events were among the reasons for treatment discontinuation 1
- In adults with binge eating disorder: Diarrhea was not specifically highlighted as a top adverse event, though gastrointestinal effects remain common 1
The FDA labeling also notes that the most common gastrointestinal side effects include decreased appetite, nausea, vomiting, and diarrhea, with these effects being dose-related 1
Mechanism and Clinical Context
Amphetamine-based medications like Vyvanse affect gastrointestinal motility through sympathetic nervous system stimulation, which can accelerate intestinal transit and reduce fluid absorption, leading to loose stools 1. This is a class effect of stimulant medications used for ADHD 2.
Management Considerations
If loose stools occur with Vyvanse:
- Assess severity: Mild diarrhea (1-2 loose stools daily) may be tolerable and self-limiting as the body adjusts to the medication 1
- Dietary modifications: Eliminate lactose-containing products, high-osmolar supplements, caffeine, and alcohol, which can worsen gastrointestinal symptoms 3
- Hydration: Maintain adequate fluid intake, though avoid excessive plain water which can worsen secretory diarrhea 4
- Symptomatic treatment: If diarrhea persists and is bothersome, loperamide (starting 2-4 mg) can be used to manage symptoms 5, 6
- Timing considerations: Taking Vyvanse with food may help reduce gastrointestinal side effects, though the medication can be taken with or without food 1
When to Be Concerned
Contact your healthcare provider if you experience:
- Severe diarrhea (≥6 loose stools daily) 3
- Signs of dehydration: Dizziness on standing, decreased urination, extreme thirst 3, 7
- Blood in stool 3
- Fever or severe abdominal pain 3, 7
- Weight loss beyond expected appetite suppression effects 1
These symptoms warrant immediate medical evaluation and may require discontinuation or dose adjustment of Vyvanse 1.