SNRIs Are Reasonable to Try and May Actually Help Your Patient's Anxiety
An SNRI is unlikely to worsen anxiety compared to Prozac and may even provide superior anxiety relief, particularly if you choose venlafaxine or duloxetine and titrate slowly from a low starting dose. 1
Why SNRIs Won't Necessarily Cause Anxiety
- SNRIs are evidence-based treatments for both MDD and GAD, with high-certainty evidence showing they improve anxiety symptoms in patients with generalized anxiety disorder 2
- The American College of Physicians found that venlafaxine may actually be superior to fluoxetine (Prozac) for treating anxiety symptoms in patients with depression 1, 3
- While SNRIs work through noradrenergic mechanisms that theoretically relate to the "fight or flight" response, paradoxically they are effective anxiolytics due to complex interactions with serotonin and other neurotransmitters 1
Evidence Supporting SNRIs for Anxiety Disorders
- Four randomized controlled trials with 911 patients demonstrated that SNRIs significantly improved primary anxiety symptoms compared to placebo in patients aged 6-18 years with social anxiety, generalized anxiety, separation anxiety, or panic disorder 1
- SNRIs as a class showed no difference in suicidal ideation or behavior compared to placebo, though they were associated with increased fatigue/somnolence 1
- Duloxetine is FDA-approved for generalized anxiety disorder in children and adolescents ≥7 years old, providing regulatory support for SNRI use in anxiety 1
Practical Implementation Strategy
Start low and go slow to minimize activation:
- Begin with a low dose and titrate cautiously to reduce the risk of initial anxiety exacerbation, dizziness, and sedation 1
- Consider starting duloxetine at 30 mg once daily for 1 week before increasing to 60 mg once daily, as this approach reduces nausea (the most common adverse effect) 1
- For venlafaxine extended-release, titrate over 2-4 weeks to reach an efficacious dose of 150-225 mg/day 1
Monitoring Requirements
- Monitor blood pressure and pulse regularly, as SNRIs have been associated with sustained clinical hypertension and increased heart rate 1
- Track height, weight, pulse, and blood pressure at each visit; no specific laboratory tests are routinely recommended 1
- Watch for behavioral activation/agitation during the first few weeks, which can occur but is uncommon 1
Common Pitfalls to Avoid
- Don't abruptly discontinue SNRIs - they require a slow taper to avoid discontinuation syndrome, particularly with venlafaxine 1
- Venlafaxine may carry greater suicide risk than other SNRIs and has been associated with overdose fatalities, so consider duloxetine as first choice if suicide risk is elevated 1
- Duloxetine should be discontinued immediately if jaundice, hepatomegaly, or signs of liver dysfunction develop, as hepatic failure has been reported 1
- Avoid combining SNRIs with MAOIs due to contraindication from serotonin syndrome risk 1
Why This Patient May Actually Benefit
- Since your patient has both MDD and GAD, SNRIs target both conditions simultaneously through dual serotonin and norepinephrine reuptake inhibition 4, 5
- Initial studies suggest dual-acting agents may have advantages over selective reuptake inhibitors in patients with comorbid anxiety and depression 4
- The fact that Prozac (an SSRI) was tried suggests the patient may benefit from the additional noradrenergic mechanism that SNRIs provide 4, 5