Mirtazapine and Sexual Dysfunction
Mirtazapine is associated with lower rates of sexual dysfunction compared to most other antidepressants, particularly SSRIs, and may actually improve sexual function in depressed patients. 1
Mechanism and Comparative Profile
Mirtazapine's favorable sexual side effect profile is likely due to its unique pharmacological properties:
- Acts as an alpha-2 adrenergic antagonist and blocks serotonin 5-HT2 and 5-HT3 receptors 2
- Unlike SSRIs, which commonly cause sexual dysfunction through stimulation of post-synaptic serotonin 5-HT2 receptors 2
Comparison with Other Antidepressants
- SSRIs have high rates of sexual dysfunction (63% of patients on second-generation antidepressants experience at least one adverse effect) 3
- Hierarchy of sexual side effects among antidepressants:
- Highest risk: Paroxetine
- Moderate risk: Sertraline, fluoxetine
- Lower risk: Fluvoxamine, mirtazapine
- Lowest risk: Bupropion 1
Evidence for Mirtazapine's Effect on Sexual Function
Multiple studies demonstrate mirtazapine's favorable sexual side effect profile:
In depressed patients taking mirtazapine:
- Women showed improvement in sexual desire (41%), arousal/lubrication (52%), and orgasm satisfaction (48%)
- Men showed more modest improvements in desire (10%), arousal/erection (23%), and orgasm satisfaction (14%) 2
When substituting mirtazapine for SSRIs in patients with SSRI-induced sexual dysfunction:
- 58% of patients had complete return to normal sexual functioning
- An additional 11% reported significant improvement in sexual function
- All patients maintained their antidepressant response 4
In a 6-month naturalistic study:
- 71.1% of patients with baseline sexual dysfunction returned to normal sexual functioning
- Only 4 patients withdrew or required dose reduction due to mirtazapine-induced sexual dysfunction 5
Clinical Implications
When to Consider Mirtazapine
- For patients concerned about sexual side effects when initiating antidepressant therapy
- As an alternative for patients experiencing sexual dysfunction with other antidepressants, particularly SSRIs 4
- For patients with depression who already have sexual difficulties, as mirtazapine may improve rather than worsen sexual function 2
Potential Drawbacks
While mirtazapine has advantages regarding sexual function, be aware of its other common side effects:
- Sedation (especially at lower doses)
- Weight gain (reported in some patients)
- Irritability
- Muscle soreness and stiffness 4
Monitoring Recommendations
- Assess baseline sexual function before starting treatment
- Regularly monitor for changes in sexual function throughout treatment
- Be aware that sexual side effects are often underreported by patients 1
Sexual dysfunction can significantly impact quality of life and medication adherence. The evidence suggests mirtazapine is a good option for patients where sexual function is a priority concern.