1. Criteria

At least one hypomanic episode has occurred.

At least one major depressive episode has occurred.

There has never been a manic episode.

The occurrence of hypomanic and major depressive episodes is not better explained by schizophrenia-spectrum or other psychotic disorders.

Symptoms cause clinically significant distress or impairment, largely through depressive symptoms or unpredictability of mood cycling.

A hypomanic episode is a distinct period of persistently elevated, expansive, or irritable mood together with persistently increased activity or energy.
The episode lasts at least 4 consecutive days and is present most of the day, nearly every day.
During the episode, 3 or more manic-type symptoms are present to a significant degree, or 4 if the mood is only irritable.
The manic-type symptoms are grandiosity, decreased need for sleep, increased talkativeness, flight of ideas or racing thoughts, distractibility, increased goal-directed activity or psychomotor agitation, and excessive involvement in high-risk activities.
The episode represents an unequivocal change in functioning that is uncharacteristic of the person when not symptomatic.
The disturbance in mood and functioning is observable by others.
The episode is not severe enough to cause marked impairment, require hospitalization, or include psychotic features.
The episode is not attributable to a substance.

If a full manic episode occurs at any point, the diagnosis is no longer bipolar II disorder and instead falls within bipolar I disorder.

2. Context

Bipolar II disorder lives in the space between recurrent depression and a history of unmistakable hypomania, without any true manic episode. In real life, many patients come to treatment because of depression, while the hypomanic periods are only recognized later in the story.
No mania: The boundary is important. If the person has ever had a full manic episode, the diagnosis is no longer bipolar II.
Hypomania threshold: Hypomania still has to be a real episode. It lasts at least 4 days, is noticeable to others, and reflects a clear change from baseline.
Depressive burden: Most of the suffering often comes from the depressive side, which is why bipolar II is so often missed early on.
Clinical focus: Quick severity and improvement tracking across bipolar states.

3. Validated scales

CGI-BP

Quick severity and improvement tracking across bipolar states.

YMRS

Useful when hypomanic symptoms are active or suspected.

MADRS

Helpful for monitoring the depressive pole over time.

4. FDA approved treatments

FDA-indicated medications used in bipolar depression or maintenance contexts relevant to bipolar II

FDA labels are not always bipolar-II-specific, but these agents are commonly drawn from bipolar depression and maintenance indications; verify the exact product labeling.

Common off-label medications

Interventional psychiatry modalities

ECT is used for severe bipolar depression or mixed states.
Ketamine is being studied and used selectively in refractory bipolar depression.
TMS is under study and sometimes used off-label in bipolar depression.

5. Top management articles

The CANMAT and ISBD guidelines for the management of patients with bipolar disorder Bipolar Disorders, 2018 update lineage
Treatment of bipolar disorder The Lancet, 2013
Bipolar II disorder: modelling, measuring, and managing Focused review literature

Simple Psych

Bipolar II Disorder

1. Criteria

Criterion A

Criterion B

Criterion C

Criterion D

Criterion E

Hypomanic episode definition

Manic episode boundary