Maintenance Treatment with Mood Stabilizers in Euthymic Bipolar II Disorder
Yes, maintenance treatment with a mood stabilizer should be initiated and continued in patients with bipolar II disorder, even when they are currently euthymic and asymptomatic. The evidence strongly supports that maintenance therapy is always initiated upon diagnosis of bipolar disorder and should continue for at least 2 years after the last episode 1.
Core Recommendation
The WHO guidelines explicitly state that lithium or valproate should be used for maintenance treatment of bipolar disorder, with treatment continuing for at least 2 years after the last episode 1. This recommendation applies to bipolar disorder broadly, including bipolar II. The decision to continue maintenance treatment beyond 2 years should preferably be made by a mental health specialist 1.
Why Maintenance Treatment is Essential
Bipolar II disorder is characterized by recurrent episodes, with depressive episodes outnumbering hypomanic episodes by a ratio of 39:1 2. The disorder carries significant risks:
- High suicide risk: The rate of completed suicide in bipolar II is at least equivalent to bipolar I disorder, with approximately 15-20% of individuals with bipolar disorder dying by suicide 2, 3
- Functional impairment: Despite being perceived as "milder," bipolar II causes significant functional and cognitive impairment 2
- Recurrence without treatment: Patients who stop maintenance treatment have 2x the risk for relapse compared to those who continue (70% vs 36%) 4
First-Line Medication Options
Based on the guidelines, your primary choices are:
Lithium - Broadest evidence base across treatment scenarios 5
- Requires close clinical and laboratory monitoring
- Should only be initiated where monitoring facilities are available 1
Valproate - Alternative first-line option 1
- Requires baseline liver function tests, complete blood counts, and pregnancy tests
- Monitor serum levels and hepatic/hematological indices every 3-6 months
Lamotrigine - Evidence for preventing depressive episodes 5, 3
- Particularly relevant given the predominance of depressive symptoms in bipolar II
Important Clinical Considerations
The "euthymic and asymptomatic" state does not negate the need for treatment. This is a common pitfall - the absence of current symptoms reflects the natural course of bipolar disorder between episodes, not resolution of the underlying condition. The goal of maintenance therapy is to:
- Prevent new episodes of depression and hypomania
- Prevent milder subsyndromal symptoms between episodes
- Maintain functional capacity 6
Special Considerations for Bipolar II
While one older study questioned the need for mood stabilizers in bipolar II patients given low conversion rates to bipolar I 7, this perspective is not supported by current guidelines or more recent evidence. The 2025 state-of-the-art review emphasizes that bipolar II requires the same serious approach to maintenance treatment as bipolar I, given the substantial morbidity, mortality risk, and functional impairment 2.
Antidepressant monotherapy should never be used - if antidepressants are needed for depressive symptoms, they must always be combined with a mood stabilizer 1. Antidepressant monotherapy can worsen prognosis and may induce hypomanic episodes 2.
Monitoring Requirements
Once maintenance treatment is established:
- Lithium: Monitor levels, renal and thyroid function, and urinalysis every 3-6 months 8
- Valproate: Monitor serum levels, hepatic and hematological indices every 3-6 months 8
- Educate patients about early warning signs of mood episodes for prompt intervention
When to Consider Discontinuation
Discontinuation may only be considered in type II disorder with mild symptoms after several years of stability, with gradual tapering while closely monitoring for relapse 6. This decision should be made in consultation with a mental health specialist, considering the increased risk of relapse, possible adverse effects, and individual preferences 1. Any discontinuation attempt requires thorough patient and family education about early signs of relapse.
The default position should be to maintain treatment - the risks of recurrence (including suicide, functional impairment, and progression of illness) substantially outweigh the burden of maintenance pharmacotherapy in most cases.