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Bipolar I disorder vs. bipolar II disorder: What's the difference?

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Bipolar IBipolar IIDifferencesTreatmentsDiagnosisSummary
Bipolar I disorder causes slightly different symptoms of mania to bipolar II disorder. Bipolar I also does not always cause episodes of depression, but bipolar II does. 
Medically reviewed by Yalda Safai, MD, MPH
Written by D. M. Pollock
Updated on May 15, 2023

If you have a type of bipolar disorder, your moods can change from very high to very low. This can feel like periods of intense energy, then shifts to episodes of sadness or hopelessness. 

Bipolar I and II disorders are the most common types of bipolar disorder. While they both cause frequent emotional shifts and are generally considered very similar, bipolar I and II have some differences in their symptoms. 

The main difference lies in how intensely you experience periods of mania with each type. Bipolar I disorder causes episodes of mania, while bipolar II causes less severe episodes, which are known as hypomania. Bipolar II disorder always causes major depressive episodes, while bipolar I disorder may or may not cause this. 

Learning more about how the two types are different can help you manage your condition most effectively. 

Bipolar I

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For a professional to diagnose you with bipolar I disorder, you must experience manic episodes that last at least 7 days. Typically, but not always, depressive episodes can also occur. These symptoms of major depression can last for 2 weeks or longer.

Sometimes, symptoms of these two emotional states can occur side-by-side. These are called mixed feature episodes, and researchers believe they may be due to an imbalance of certain chemicals in the brain. 

People experiencing bipolar I disorder may require medical attention to help manage their symptoms during episodes of mania. 

During a manic episode, you may feel:

  • high energy
  • extremely irritable 
  • restlessness
  • higher energy levels than usual
  • the need for less sleep than usual 
  • lack of tiredness
  • difficulty concentrating

During a manic episode, you may find it difficult to perform well at work, in your social life, or in any other responsibilities that you typically manage. 


Bipolar II

Bipolar II disorder involves a person experiencing at least one major depressive episode and one hypomanic episode. During a hypomanic episode, you may notice the same behaviors and feelings as during a manic episode, but not as intense. Hypomanic episodes typically last a few days, but this can vary between people. 

Symptoms of bipolar II disorder are not typically severe enough to require hospitalization in people experiencing a hypomanic episode. 

Sometimes, mental health professionals may misdiagnose bipolar II disorder as major depression. This is because the depressive symptoms of bipolar II disorder can be the reason that a person seeks medical help, since hypomanic episodes may feel good or even improve performance at school or in the workplace.

Key differences 

Bipolar I and II disorders are very similar. In short, what makes them different is the severity of manic episodes and the presence of depressive episodes. The following table provides a short summary of the differences.

Bipolar I disorderBipolar II disorder
At least one manic episode lasting at least one week, or requiring medical attention.At least one hypomanic episode.
May not include an episode of major depression.At least one episode of major depression

Manic episodes

Bipolar I disorder involves severe manic episodes that may require hospitalization to help manage symptoms. These episodes typically last at least one week and affect your ability to work and socialize.

Bipolar II disorder involves periods of hypomania, which can cause you to feel less intense manic symptoms that typically last at least a few days. Hypomania does not affect your ability to function at work, or in your personal life or cause any symptoms of psychosis. 

Major depressive episodes

Another main difference between bipolar I and II disorder is the prevalence of depressive episodes. For a healthcare professional to diagnose someone with bipolar II disorder, they must experience at least one major depressive episode that lasts at least 2 weeks

On the other hand, with bipolar I disorder, you may still experience major depressive episodes, but professionals can still diagnose you with the condition if you do not experience them. 

A depressive episode may include:

  • an inability to feel joy
  • decrease or increase in appetite or body weight
  • fatigue (low energy)
  • lack of energy
  • excessive guilt
  • difficulty making decisions
  • worthlessness
  • suicidal thoughts

If you or someone you know is considering suicide or self-harm, please seek support:

While you wait for help to arrive, stay with someone and remove any weapons or substances that can cause harm. You are not alone.

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Cyclothymia disorder

Cyclothymia disorder is another type of bipolar disorder. This is a rare condition where you experience the emotional ups and downs of bipolar disorder, but they are mild and more frequent in comparison to those in bipolar I or II disorder. You may notice your mood shift up and down from your personal baseline.

People diagnosed with both bipolar I and bipolar II disorders can experience aspects of cyclothymia, but research shows that most people affected by it are categorized as experiencing bipolar II.

Treatments for bipolar I and II

Whether you have bipolar I or II disorder, a healthcare professional will typically recommend medications and therapy to help manage your symptoms. It is important to follow the professional’s instructions regarding lifestyle choices, such as:

  • alcohol
  • exercise
  • diet
  • sleep
  • managing stress

Medications

Each person with a diagnosis of bipolar disorder will receive a personalized treatment plan depending on their individual needs. You can work with a healthcare professional to find the best treatment for you. 

Some medications that you may be recommended include:

  • Mood stabilizers: These medications help manage hypomanic or manic episodes. Examples include lithium (Lithobid) and valproic acid (Depakene).
  • Antidepressants: A mental health professional may recommend an antidepressant medication to help with any episodes of major depression. They may prescribe you these medications alongside a mood-stabilizing medication. Examples include sertraline (Zoloft) and fluoxetine (Prozac).
  • Antipsychotic medications: These medications can help manage mania that causes hallucinations or behavioral changes. Examples include olanzapine (Zyprexa) and aripiprazole (Abilify).

Researchers still debate the effectiveness of antidepressants in treating bipolar disorder. According to one 2018 review of studies, they are still safest in treating bipolar disorder II. Discussing your options with a healthcare professional can be helpful.

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Therapy methods

Talk therapy can help teach you how to manage the symptoms of bipolar disorder. It works by helping you learn how to identify and manage difficult emotions and behaviors that are affecting your life. 

It can be helpful for your family members too, guiding them on how they can best support you. 

Cognitive behavioral therapy (CBT) is a common type of therapy for helping manage bipolar disorder. It involves both one-to-one and group sessions. CBT can help you manage your thoughts and find healthy ways to deal with problems. 

If you find talk therapy and medications do not help, other therapies can help treat bipolar disorder. One example is electroconvulsive therapy (ECT). This procedure stimulates your brain using electricity (while you’re under anesthesia) to help reduce symptoms. 

Diagnosis

mental health professional typically diagnoses bipolar disorder. As a specialist, they will know what questions to ask you. These may include questions about your behavior that you may not be able to answer easily. Bringing a friend or family member with you to your appointment may help you answer these questions. 

A diagnosis will involve the professional looking at your medical history and current symptoms of bipolar disorder. They may perform a blood test and physical checkup to rule out other causes for your symptoms. 

Summary

Bipolar I disorder involves an episode of mania that lasts at least one week and may or may not cause major depressive episodes. Bipolar II disorder causes hypomania, which is less severe than mania, and diagnosis requires a person to experience an episode of major depression. 

Regardless of the type of bipolar disorder you have, a healthcare professional will likely recommend a combination of medication and therapy to help manage your symptoms.

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