How is bipolar II disorder different from bipolar I disorder?

People with BPI and BPII disorder both experience a combination of depressive and hypomanic episodes. However, people diagnosed with BPI disorder experience full manic episodes, which are longer and more severe ‘highs’. People diagnosed with BPII disorder do not experience full manic episodes.

Diagram shows the types of 'low' and 'high' episodes in BPI versus BPII.

Bipolar II disorder (BPII) Bipolar I disorder (BPI)
'Lows'
  • Similar in both. Unlikely to include psychotic experiences.
  • Similar in both. May include psychotic experiences.
'Highs'
  • Shorter, milder
  • Can usually carry out work, social, and family commitments as normal or with minimal disruption
  • Does not usually require hospitalisation.
  • No psychotic experiences
  • Longer, more severe; includes mania
  • Difficulties carrying out work, social, and family commitments as normal
  • May require hospitalisation
  • May include psychotic experiences

People with BPII disorder tend to experience more depressive episodes and have less time between episodes, compared to BPI disorder. Although the highs are shorter and milder in BPII disorder, the lows can be just as severe. Like BPI, BPII is a serious condition and can affect a person’s life.