Mood Stabilizers for Bipolar Disorder: Lithium, Valproate, Lamotrigine, and Carbamazepine

When mood becomes intensely elevated, deeply depressed, or unpredictable enough to disrupt everyday life, treatment is often aimed at something more fundamental than simply making a person “feel better.” The goal is stability: reducing the severity of mood episodes and helping prevent them from returning.

This is where mood stabilizers play an important role.

In U.S. psychiatric practice, the term mood stabilizer commonly refers to medications used in the treatment of bipolar disorder, particularly lithium and several anticonvulsant medications. Certain second-generation antipsychotics can also have important roles in treating mania, bipolar depression, or preventing future episodes, depending on the specific medication and clinical situation.

Among the best-known traditional options are lithium, valproate, lamotrigine, and carbamazepine. They are sometimes discussed together, but they are not interchangeable. Each has its own strengths, limitations, safety considerations, and place in treatment.

Lithium: The Classic Mood Stabilizer

Lithium has been used in modern psychiatric treatment for decades and remains one of the most important medications for bipolar disorder.

In the United States, lithium is FDA-approved for treating acute manic and mixed episodes of bipolar I disorder and for maintenance treatment intended to reduce the recurrence of mood episodes.

What makes lithium particularly interesting is that it is not simply a sedative. Its precise mechanism in bipolar disorder is still not completely understood. Research suggests that lithium influences several cellular signaling systems involved in the regulation of brain activity rather than acting through one single neurotransmitter or receptor.

For someone experiencing mania, the desired effect is not to erase emotion or personality. The clinical goal is to reduce pathological mood elevation, racing thoughts, impulsivity, agitation, and other symptoms while allowing more stable functioning to return.

Lithium has also received considerable attention because research has associated long-term treatment with a potentially lower risk of suicide in people with mood disorders. However, the size and certainty of this effect remain debated: observational research and several earlier analyses have been supportive, while more recent analyses of randomized trials have found the evidence less conclusive.

Why Blood Tests Matter With Lithium

Lithium requires careful monitoring because the difference between an effective blood level and a potentially toxic level can be relatively narrow.

For this reason, clinicians monitor serum lithium concentrations and may also check kidney function, thyroid function, electrolytes, and calcium during treatment. Dehydration, major changes in salt intake, kidney problems, and interactions with medications such as some NSAIDs, diuretics, and blood-pressure medications can affect lithium concentrations.

This monitoring can sound inconvenient, but it has an important purpose: lithium can be highly useful when it is prescribed and followed carefully.

Valproate: Particularly Important in Mania and Mixed States

Valproate—often prescribed in the United States as divalproex sodium—was originally developed as an anticonvulsant. It later became an important treatment option in psychiatry.

Divalproex is FDA-approved for the treatment of acute manic or mixed episodes associated with bipolar disorder. Extended-release formulations are available, which can make once-daily treatment possible for some patients.

Its effects appear to involve several mechanisms, including changes in GABA signaling and modulation of voltage-sensitive ion channels. The result is a reduction in excessive neuronal excitability, although its mood-stabilizing action cannot be explained by one mechanism alone.

Valproate is often considered when mania is prominent or when symptoms of depression and mania appear together.

One important correction to a common misconception is that valproate does not eliminate the need for medical monitoring. Depending on the situation, clinicians may monitor valproate blood levels as well as liver function and blood-cell or platelet counts. The medication also carries important reproductive and pregnancy-related risks that must be discussed before treatment.

So although valproate can be very effective, convenience should never be confused with an absence of medical supervision.

Lamotrigine: More About Prevention Than Controlling Mania

Lamotrigine is another anticonvulsant that has become an important medication in bipolar treatment, but its role is quite different from that of lithium or valproate.

In the United States, lamotrigine is FDA-approved for maintenance treatment of bipolar I disorder, helping delay the return of mood episodes after an acute episode has already been treated. It is not FDA-approved as a treatment for acute mania, and its effectiveness for acute manic or mixed episodes has not been established.

Lamotrigine is particularly valued in clinical practice when prevention of depressive episodes is an important concern. Unlike several psychiatric medications, it is not typically associated with substantial weight gain, although—as with every medication—side effects and individual responses vary.

Its effects include actions on voltage-sensitive sodium channels and glutamate release, although the precise mechanism responsible for its benefit in bipolar disorder remains uncertain.

Why Lamotrigine Must Be Increased Slowly

Lamotrigine deserves special attention because it can cause skin reactions.

Most rashes are not life-threatening, but rare cases of Stevens-Johnson syndrome and toxic epidermal necrolysis have occurred. Because it is impossible to reliably determine at home whether a new rash will remain harmless, current prescribing information states that lamotrigine should generally be discontinued at the first sign of rash unless the rash is clearly unrelated to the medication.

The risk is one reason lamotrigine is started at a low dose and increased gradually. Increasing the dose too quickly or combining it with valproate without appropriate dose adjustment can raise the risk of serious skin reactions.

A new rash, fever, swollen lymph nodes, facial swelling, or other signs of a significant reaction should therefore be evaluated promptly by a healthcare professional.

Carbamazepine: Effective, but Interactions Require Attention

Carbamazepine is another anticonvulsant with a role in bipolar disorder. An extended-release form is FDA-approved for the treatment of acute manic or mixed episodes associated with bipolar I disorder.

Its therapeutic action is thought to involve stabilization of voltage-gated sodium channels, reducing repetitive neuronal firing.

Carbamazepine can be useful, but it has one characteristic that makes careful prescribing especially important: drug interactions.

The medication strongly affects liver enzymes involved in metabolizing many other drugs. As a result, carbamazepine can lower the blood concentrations and effectiveness of certain medications taken at the same time—including some hormonal contraceptives and other psychiatric medications.

It also requires appropriate laboratory monitoring. Depending on the patient, clinicians may evaluate blood counts, liver function, sodium levels, and carbamazepine concentrations. Genetic testing for the HLA-B*1502 allele is recommended before treatment in people with ancestry from populations in which this genetic variant is more common because of an increased risk of severe skin reactions.

This is why a complete medication list is essential whenever carbamazepine is being considered.

The Same Diagnosis Does Not Mean the Same Medication

One of the most important ideas behind mood-stabilizing treatment is that there is no universally “best” medication.

A person whose main difficulty is severe acute mania may need a different strategy from someone whose greatest problem is recurrent bipolar depression. Previous treatment response, other medical conditions, pregnancy potential, kidney and liver function, medication interactions, side effects, and the pattern of past episodes can all influence the decision.

• Lithium: May be especially valuable for long-term stabilization and mania.
• Valproate: Can be effective in acute manic and mixed episodes.
• Lamotrigine: Has an important role in maintenance treatment and prevention, particularly when depressive episodes are a concern.
• Carbamazepine: Can treat mania but requires particular attention to interactions and laboratory monitoring.

Modern treatment therefore is not simply about suppressing symptoms. It is about finding the safest way to create enough stability for sleep, relationships, work, decision-making, and everyday life to become more predictable again.

These medications can make that possible for many people—but their benefits depend on thoughtful selection, appropriate monitoring, and regular communication with a prescribing clinician. Medication should not be started, stopped, or adjusted without professional guidance.

References

• Yatham LN, Kennedy SH, Parikh SV, et al. Canadian Network for Mood and Anxiety Treatments (CANMAT) and International Society for Bipolar Disorders (ISBD) 2018 Guidelines for the Management of Patients With Bipolar Disorder. Bipolar Disorders. 2018;20(2):97–170. doi:10.1111/bdi.12609.
  Annotation: A comprehensive evidence-based guideline covering acute mania, bipolar depression, maintenance treatment, lithium, divalproex, lamotrigine, carbamazepine, and antipsychotic medications. The complete publication spans pp. 97–170.
• Department of Veterans Affairs & Department of Defense. VA/DoD Clinical Practice Guideline for the Management of Bipolar Disorder. Version 1.0. 2023.
  Annotation: A U.S.-based clinical guideline describing evidence-based management of mania, hypomania, bipolar depression, and pharmacologic treatment. Particularly useful for comparing medications and combinations used during different phases of bipolar disorder. See also Appendix E, Table E-6, p. 157 for evidence concerning medication combinations and treatment phases.
• U.S. National Library of Medicine. DailyMed. Lithium Carbonate Prescribing Information.
  Annotation: Current U.S. prescribing information confirms lithium's indications for acute manic or mixed episodes and maintenance treatment of bipolar I disorder and explains serum-level, kidney, thyroid, electrolyte, and safety monitoring. Relevant material appears in Sections 1, 2.1–2.3, 5, and 7.
• U.S. National Library of Medicine. DailyMed. Divalproex Sodium Extended-Release Tablets Prescribing Information.
  Annotation: Provides current U.S. information on divalproex for acute manic or mixed episodes, laboratory monitoring, adverse effects, drug interactions, liver toxicity, and reproductive risks. Relevant material appears in Sections 1.1, 2.1, 5, 7, and 8.
• U.S. National Library of Medicine. DailyMed. Lamotrigine Tablets Prescribing Information.
  Annotation: Confirms lamotrigine's role in maintenance treatment of bipolar I disorder, explains that effectiveness for acute manic or mixed episodes has not been established, and details the boxed warning regarding serious skin reactions. See Sections 1.2, 2.4, and 5.1.
• U.S. National Library of Medicine. DailyMed. Equetro (Carbamazepine Extended-Release) Prescribing Information.
  Annotation: Documents the FDA-approved use of extended-release carbamazepine for acute manic or mixed episodes associated with bipolar I disorder and discusses blood monitoring, serious dermatologic reactions, genetic risk, liver effects, and clinically significant drug interactions. See Sections 1.1, 2.1–2.2, 5, and 7.
• Nabi Z, Stansfeld J, Plöderl M, et al. Effects of Lithium on Suicide and Suicidal Behaviour: A Systematic Review and Meta-Analysis of Randomised Trials. Epidemiology and Psychiatric Sciences. 2022;31. doi:10.1017/S204579602200049X.
  Annotation: Examines randomized evidence concerning lithium and suicidal behavior and highlights why the often-repeated claim of a definite anti-suicide effect should be presented with appropriate scientific caution.