Naltrexone is NOT a mood stabilizer and should not be used for that purpose
Naltrexone is FDA-approved only for opioid and alcohol use disorders, not for mood stabilization in bipolar disorder or other primary mood disorders. The evidence provided does not support its use as a mood stabilizer in the traditional psychiatric sense.
What Naltrexone Actually Does
Naltrexone is a mu-opioid receptor antagonist with two FDA-approved indications 1:
- Treatment of opioid dependence (maintaining abstinence)
- Treatment of alcohol dependence
The drug works by blocking opioid receptors, preventing the euphoric effects of opioids and reducing alcohol cravings 2.
The Mood Stabilization Confusion
The confusion likely stems from two distinct contexts where naltrexone intersects with mood:
1. Naltrexone-Bupropion Combination for Depression (Not Mood Stabilization)
When combined with bupropion (an antidepressant), naltrexone-bupropion ER has shown some benefit for depressive symptoms, not bipolar mood stabilization 3:
- A small open-label study showed improvement in depressive symptoms sustained at 24 weeks in women with major depressive disorder 3
- This is treating unipolar depression, not stabilizing bipolar mood swings
- The antidepressant effect comes primarily from the bupropion component, not naltrexone 3
- It is "reasonable to prioritize naltrexone-bupropion ER for appropriate patients with depressed mood" 3 - but this refers to depression in the context of obesity treatment, not primary mood disorder treatment
2. Low-Dose Naltrexone (LDN) Research
Recent research on low-dose naltrexone (1-4.5 mg daily) as augmentation for depression shows mixed results:
- One small proof-of-concept trial (n=12) showed some benefit for breakthrough depressive symptoms when added to dopaminergic antidepressants 4
- A larger randomized controlled trial (n=37) found no difference between LDN and placebo for moderate depression 5
- These studies examined depression treatment, not mood stabilization for bipolar disorder
What About Depression as a Side Effect?
The FDA label warns about depression and suicidality with naltrexone 1, though the evidence is contradictory:
- Depression, suicide attempts, and suicidal ideation have been reported in post-marketing surveillance, but no causal relationship has been demonstrated 1
- Multiple studies in opioid-dependent patients found naltrexone did not worsen depressive symptoms 6, 7
- One study showed patients adherent to naltrexone had fewer depressive symptoms than non-adherent patients 6
- A double-blind placebo-controlled trial in healthy volunteers found naltrexone did not significantly alter mood over 2 months 8
True Mood Stabilizers for Bipolar Disorder
For actual mood stabilization in bipolar disorder, evidence-based treatments include 9:
- Lithium
- Valproate/divalproex
- Carbamazepine
- Atypical antipsychotics (olanzapine, risperidone, quetiapine, aripiprazole)
- Lamotrigine (particularly for bipolar depression)
Critical Clinical Pitfalls
- Do not confuse "mood improvement" with "mood stabilization" - these are fundamentally different therapeutic goals
- Naltrexone blocks opioid receptors - it cannot be used in patients requiring opioid pain management 3
- Hepatotoxicity risk - liver function tests should be monitored at baseline and every 3-6 months 2
- Monitor for depression/suicidality in all patients taking naltrexone, particularly those under 24 years 3, 1
Bottom Line
Naltrexone has no established role as a mood stabilizer. Its only psychiatric indication is substance use disorders (opioid and alcohol dependence). While naltrexone-bupropion may help with unipolar depression in specific contexts (primarily obesity treatment), this does not translate to mood stabilization for bipolar disorder or other conditions requiring true mood stabilizers.