Can Missing One Day of Cymbalta and Vyvanse Cause Withdrawal Symptoms?
Yes, missing a single day of Cymbalta (duloxetine) can absolutely cause withdrawal symptoms including rebound anxiety, even after just one missed dose, though Vyvanse discontinuation after one day is less likely to be the primary culprit.
Understanding Duloxetine (Cymbalta) Withdrawal
Duloxetine has a well-documented discontinuation syndrome that can occur rapidly after missing doses. 1
- Duloxetine withdrawal symptoms occur at rates ≥1% and include: dizziness, headache, nausea, diarrhea, paresthesia, irritability, vomiting, insomnia, anxiety, hyperhidrosis, and fatigue 1
- These symptoms can begin within 24-48 hours of the last dose, which aligns perfectly with your patient's timeline 2
- SNRIs like duloxetine (along with paroxetine and venlafaxine) are among the antidepressants most likely to cause withdrawal symptoms, even after brief interruptions 3, 4
- Research specifically documents that withdrawal symptoms can occur after missing a single dose of SNRI medications 5
Understanding Lisdexamfetamine (Vyvanse) Withdrawal
Vyvanse withdrawal after one day is possible but typically manifests differently than what's described as "strange symptoms" or anxiety. 6
- Amphetamine withdrawal symptoms include: dysphoric mood, depression, fatigue, vivid unpleasant dreams, insomnia or hypersomnia, increased appetite, and psychomotor retardation or agitation 6
- These symptoms typically develop after prolonged use followed by abrupt discontinuation, not after missing a single dose 6
- At the 20mg dose (relatively low), acute withdrawal after one day would be unlikely to cause significant symptoms 6
Colonoscopy Medication Considerations
Procedural medications are unlikely to be causing her current symptoms, but drug interactions during the procedure warrant consideration. 3
- Standard colonoscopy sedation (midazolam, fentanyl, propofol) does not typically cause post-procedure anxiety or "strange symptoms" beyond 6-12 hours 3
- However, if fentanyl was used during the procedure, there is a theoretical risk of serotonin syndrome when combined with duloxetine (an SNRI with serotonergic activity), though this would have manifested during or immediately after the procedure, not the next day 3
- Ondansetron (commonly given for nausea during colonoscopy) combined with duloxetine also carries serotonin syndrome risk, but again, this would be acute 3
Clinical Recommendation
The patient's symptoms are most consistent with duloxetine discontinuation syndrome, not Vyvanse withdrawal or colonoscopy medications. 1, 4
Immediate Management:
- Resume duloxetine 20mg immediately - symptoms should improve within 24-48 hours of restarting 1, 2
- Monitor for resolution of anxiety, dizziness, and other withdrawal symptoms 1
- Educate the patient that duloxetine should never be stopped abruptly, even for one day 1, 7
Future Procedural Planning:
- For future procedures, duloxetine should be continued on the day of the procedure unless there is a specific contraindication 3
- SNRIs like duloxetine are generally safe to continue perioperatively and stopping them increases risk of withdrawal syndrome 3, 7
- Vyvanse can typically be held on the day of procedures without significant withdrawal risk at therapeutic doses 6
Important Caveat:
- While duloxetine withdrawal is the most likely explanation, if symptoms persist after resuming medication or worsen, consider serotonin syndrome from drug interactions during the colonoscopy (though timing makes this less likely) 3, 1
- Serotonin syndrome would present with neuroexcitatory symptoms, autonomic dysfunction, and neuromuscular abnormalities - not just anxiety alone 3
The key teaching point: SNRIs like duloxetine have short half-lives and can cause withdrawal symptoms even after missing a single dose, particularly at the 24-48 hour mark. 5, 2, 4