The types of bipolar disorder, and how they compare

Bipolar disorder is defined by swings between elevated states (mania or the milder hypomania) and depressive lows. The types differ mainly in how high the highs go — and, counter-intuitively, the type with the less dramatic highs is not the milder illness. The depressive burden of bipolar II is often heavier and longer.

Telling the types apart is a clinical job that hinges on a careful history of the high periods, which are easy to miss or misremember as simply "feeling good". The bipolar screening here is a first step for spotting that pattern; the comparison below is the one people most often search for.

The main types, one by one

Bipolar I disorder

Defined by at least one full manic episode — a week or more of extreme elevation, energy, or irritability severe enough to disrupt life or require hospital care. Depressive episodes usually occur too, but are not required for the diagnosis.

Bipolar II disorder

Defined by at least one hypomanic episode (a milder, shorter high that never tips into full mania) plus at least one major depressive episode. Not "mild bipolar" — the depressions are often the dominant, most disabling feature.

Cyclothymic disorder

Two years or more of numerous hypomanic and depressive symptoms that never quite meet the threshold for a full episode. Chronic and low-grade, but disruptive, and it can progress to bipolar I or II.

Bipolar I vs Bipolar II

The distinction people search for most: the single difference that separates the two, why bipolar II is not "the mild one", and why the difference changes treatment. Read more →

See also the bipolar disorder overview and the full symptoms guide.