The five mood stabilizers most commonly prescribed as first-line treatments for bipolar disorder are lithium, valproate (Depakote), lamotrigine (Lamictal), quetiapine (Seroquel), and carbamazepine (Tegretol). Each works differently, carries a distinct side effect profile, and suits different phases of the illness. Lithium remains the gold standard, but the best choice depends on whether the goal is treating acute mania, preventing depressive episodes, or long-term maintenance.
1. Lithium
Lithium is the oldest and most studied mood stabilizer, effective for both acute manic episodes and long-term prevention of relapse. It works through several pathways in the brain: it dials down overactive signaling between nerve cells, supports the growth and survival of neurons by boosting a key brain growth factor (BDNF), and reduces inflammation in brain tissue. No other mood stabilizer has this breadth of biological activity, which is one reason it remains a cornerstone of bipolar treatment decades after its introduction.
The tradeoff is that lithium has a narrow therapeutic window. Blood levels need to stay between roughly 0.6 and 1.2 mEq/L to be effective without becoming toxic. During acute mania, doctors aim for the higher end of that range; for maintenance, a level between 0.4 and 0.99 mEq/L is typical, and older adults generally do best at the lower end (0.4 to 0.8 mEq/L). This means regular blood draws, especially early in treatment. You’ll also need periodic thyroid and kidney function tests, since lithium can affect both organs over time. Thyroid checks are recommended at three months and then every six months; kidney function is monitored at three months and then at least annually.
Weight gain on lithium is moderate compared to some alternatives. Common early side effects include increased thirst, frequent urination, mild hand tremor, and digestive upset, most of which improve as your body adjusts.
2. Valproate (Depakote)
Valproate, sold as divalproex sodium, is one of the most widely prescribed alternatives to lithium for acute mania. In a landmark trial comparing it head-to-head with lithium and placebo in 179 hospitalized patients, treatment failed due to lack of effectiveness in 30% of those on valproate, 33% on lithium, and 51% on placebo. The two drugs performed similarly for mania, but valproate was slightly better tolerated: only 6% of patients stopped due to side effects, compared to 11% on lithium.
Where valproate falls short is in preventing depressive episodes. It’s considerably less effective than lithium or lamotrigine for the depressive side of bipolar disorder, so it’s most useful for people whose illness leans heavily toward mania. It’s also the mood stabilizer most likely to cause weight gain, according to the Mayo Clinic. Blood monitoring is more intensive early on: a complete blood count is checked one to two weeks after starting, again after each dose increase, then every three months for the first year. Liver function tests follow a similar schedule, since the drug is processed through the liver.
Valproate carries serious risks during pregnancy, including neural tube defects, and is generally avoided in women of childbearing age unless no alternative works.
3. Lamotrigine (Lamictal)
Lamotrigine fills a gap the other mood stabilizers leave open: it’s one of the most effective options for preventing bipolar depressive episodes. It has little effect on acute mania, so it’s not the right choice for someone in a manic crisis, but for long-term maintenance in people who struggle primarily with depression, it’s often preferred. It also has the friendliest metabolic profile of the group. The Mayo Clinic identifies it as the mood stabilizer least likely to cause weight gain.
The major concern with lamotrigine is a potentially life-threatening skin reaction called Stevens-Johnson syndrome. When the drug is started slowly using a standard titration schedule, the risk drops from about 1% to somewhere between 0.1% and 0.01%. That schedule looks like this: 25 mg daily for the first two weeks, 50 mg for weeks three and four, 100 mg at week five, with a target dose of 150 to 250 mg daily. Rushing this process significantly raises the danger. Even with proper titration, about 10% of people develop a benign rash that can be hard to distinguish from the dangerous kind, which sometimes leads to unnecessary discontinuation.
Lab monitoring for lamotrigine is lighter than for the others. Blood counts, liver, and kidney tests are done only as clinically indicated rather than on a fixed schedule, making it one of the lowest-maintenance options for ongoing care.
4. Quetiapine (Seroquel)
Quetiapine is technically an atypical antipsychotic, but it’s prescribed so frequently for bipolar disorder that it functions as a mood stabilizer in practice. It’s FDA-approved for both acute manic and depressive episodes, giving it a versatility that pure anticonvulsant mood stabilizers lack. For maintenance, it’s approved as an add-on to lithium or valproate rather than as a standalone treatment, since its effectiveness as the sole long-term medication hasn’t been established in controlled trials.
The main downsides are sedation and metabolic effects. Quetiapine tends to cause significant drowsiness, which is why it’s often dosed at bedtime. Over time, it can lead to weight gain, elevated blood sugar, and changes in cholesterol. These metabolic shifts require monitoring with periodic blood work. For some people, the sedation is actually a benefit, particularly those who struggle with insomnia or agitation during mood episodes.
5. Carbamazepine (Tegretol)
Carbamazepine is effective for acute mania and maintenance, but it’s typically reserved for cases where lithium and valproate haven’t worked. The reason comes down to drug interactions. Carbamazepine activates liver enzymes that break down roughly 25% of all medications, including many antipsychotics and antidepressants. This means adding carbamazepine to an existing medication regimen can reduce the effectiveness of other drugs a person is already taking, sometimes dramatically.
Blood monitoring is fairly intensive. A complete blood count is checked after each dose increase and then annually, while liver function is tested monthly for the first three months. These precautions exist because carbamazepine can, in rare cases, suppress bone marrow function or cause liver damage. The drug also lowers blood levels of hormonal contraceptives, which is an important consideration for women relying on birth control pills.
How These Five Compare at a Glance
- Best for acute mania: Lithium, valproate, and carbamazepine are all effective. Quetiapine is often added as a combination partner.
- Best for preventing depression: Lamotrigine stands out. Quetiapine also covers depressive episodes. Lithium offers moderate protection against both poles.
- Lowest weight gain risk: Lamotrigine, followed by carbamazepine. Valproate carries the highest risk.
- Least blood work needed: Lamotrigine requires monitoring only when symptoms suggest a problem. Lithium and valproate need the most frequent testing.
- Fewest drug interactions: Lithium and lamotrigine are relatively clean. Carbamazepine is the most problematic.
Finding the Right Fit
The “best” mood stabilizer depends on the pattern of your illness. If mania is the bigger problem, lithium or valproate is usually tried first. If depression dominates, lamotrigine is often the starting point. Many people with bipolar disorder end up on a combination, such as lithium plus lamotrigine or valproate plus quetiapine, because the illness has both manic and depressive components that a single drug can’t fully cover.
Practical factors also matter. If you travel frequently or dislike blood draws, lamotrigine’s minimal monitoring is appealing. If you’re taking several other medications, carbamazepine’s interaction profile might make it a poor fit regardless of how well it controls mood. Weight concerns steer some people away from valproate and quetiapine and toward lamotrigine. These are all reasonable factors to weigh alongside how well each drug controls your specific symptoms.