Hi, Butterfly. Charlotte'sWeb sketched in some of the main points, but there are some serious errors in the details. Let's start over:   The distinguishing point between BP I and BP II is the severity of the mania. Let's start with BP II. Think "mania lite," clinically known as hypomania. We're talking euphoric and over-exuberant on one hand, and irritated on the other. In either case, these are high-energy states where inhibitions get lost and impulse control is difficult. Those in hypomania can be extremely sociable, creative, productive, sexual - or very grouchy (think road rage).   With BP II, hypomania is as high as things crank up. You're more out of character than out of control. People may look at you funny, and you may get in trouble, but no one is about to dial 911.   People with BP I can also experience hypomania, but this time the tendency is to cycle up into full-blown mania. Here, things are out of control. You are no longer in charge of your brain. You may be euphoric, you may experience raging anger. Unless you are treated right away, you are at risk of getting into serious trouble. Jail, job loss, relationship bust-ups - anything can happen.   What tends to get lost in the hypomania and mania distinctions is that both BP Is and BP IIs are depressed way more than they're manic or hypomanic. Both are essentially depressions with speed bumps. BP IIs have a particularly rough time in the depression phase. Their depressions tend to last longer, with little relief. Many BP IIs only cycle up to a very light hypomania that can easily be mistaken for normal. Thus, they tend to get misdiagnosed with depression and mistreated on antidepressants, which may make them worse.   Psychiatrists are starting to catch on to the fact that the depressive phase of the illness needs to be addressed. The antipsychotic Seroquel has an FDA indication for treating BP depression (as does combo Zyprexa-Prozac), but these should not be regarded as long-term meds due to their side-effect profiles. Lamictal, a mood stabilizer has been used to treat BP depression, but has been underwhelming in clinical trials (it has an FDA indication for preventing BP relapse).   One way to treat BP depression is to stabilize the mood cycle - ie, if you're not cycling, then you're not cycling down. Lithium, Depakote, Tegretol, and Lamictal are the most common mood stabilizers. All are generic. They can be used for BP I and BP II.   The same principle applies for cycling up, which is why mood stabilizers are also used against mania and hypomania on BP I and BP II.   Psychiatrists will take a number of things into consideration in prescribing mood stabilizers. Lithium works reasonably well against both depression and mania/hypomania. Depakote and Tegretol are a lot stronger on the mania side and weak on the depression side. Lamictal is much stronger on the depression side and weaker on the mania side.   Ideally, BP Is and IIs should only be treated with mood stabilizers, but antipscyhotic meds work well against mania and psychotic features in mania. Antipsychotic meds are very useful for 911 manic states, when meds overkill is advisable, but owing to their side effects are problematic for the long term. Unfortunately, many psychiatrists fail to take their patients off antipsychotics. A lot of this has to do with drug industry marketing rather than good science.   Just to totally confuse you, the antipsychotic Seroquel is often prescribed in tiny doses to both BP Is and IIs as a sleep aid.   Finally: It is a mistake to consider BP II a light version of BP I. The depressions in BP II are more prevalent and devasting. Depression is also more disabling and life-threatening than mania. Thus, both types of bipolar need to be taken equally seriously.