Mood stabilizers are medications used to regulate fluctuations in mood. They are primarily used to treat bipolar disorder, a psychiatric illness in which a patient experiences extreme swings in mood, ranging from mania to depression.

This class of medications consists of lithium and certain anticonvulsant medications. These medications are useful in both the immediate treatment of current symptoms of an episode and in preventing future episodes.

The cause of bipolar disorder is not well understood. However, it appears that brain chemistry plays a major role in its development. Brain chemicals called neurotransmitters convey messages between the nerves. Dysregulations in the functions of these neurotransmitters are believed to cause alterations in mood.

Mood stabilizers are believed to work by changing the levels of neurotransmitters and the response of the receptors that receive those transmitters in the brain. For instance, lithium, a common treatment for bipolar disorder, appears to affect the neurotransmitter dopamine by interfering with its receptors while promoting the increase of serotonin, another neurotransmitter. Some recent studies have implied that mood stabilizers might have neuroprotective effects (e.g., keep brain cells from dying when stressed).

Some people respond better to one mood stabilizer than another. Factors such as other medical conditions (e.g., kidney disease) and side effects help determine which mood stabilizer a physician may prescribe.

Treatment with mood stabilizers is often lifelong. Patients who stop taking them will usually relapse, often within the first six months. Treatment following relapse can be more difficult, because medication may no longer be effective in some patients. Relapses can be severe, so medications are tapered off slowly if a physician feels a change in therapy is necessary.

Mood stabilizers may take a few days to several weeks to reach maximum effectiveness. They may be prescribed alone, together with other mood stabilizers, with antidepressants, or with other agents to treat specific symptoms (e.g., insomnia, hallucinations).