Lithium vs Lamictal
How lithium and lamotrigine compare, two mood stabilizers used in bipolar disorder.
How they're similar
Lithium and lamotrigine are both mood stabilizers used in bipolar disorder. Despite their differences, they share several features.
- Both are mood stabilizers used in bipolar disorder.
- Both are long-term maintenance medications, taken to prevent mood episodes over time rather than for quick relief.
- Both need a careful approach to dosing.
- Neither should be stopped abruptly, so both need a plan made with a prescriber.
How they differ
The differences are substantial, and they shape when each one is used. The table below sums up the core points, with more detail underneath.
| Lithium | Lamotrigine (Lamictal) | |
|---|---|---|
| Drug type | Mood stabilizer | Mood stabilizer |
| Best at preventing | Mood episodes broadly, with strong evidence | The depressive episodes of bipolar disorder |
| Effect on acute mania | Effective for manic episodes | Less effective for acute mania |
| Monitoring needed | Regular blood tests for lithium level, kidney, and thyroid | No routine blood-level monitoring |
| Key risk | Narrow range between effective and toxic levels | Rare but serious skin reactions, an FDA boxed warning |
| Effect on weight | Can cause weight gain | Relatively weight-neutral |
The first difference is what each one is best at. Lithium is effective across bipolar disorder, including manic episodes, and it has strong evidence for preventing episodes and for reducing the risk of suicide. Lamotrigine is particularly good at preventing the depressive episodes of bipolar disorder, and it is less effective for acute mania.
Monitoring is a major practical difference. Lithium needs regular blood tests. These check the lithium level, which has a narrow range between effective and toxic, and they also monitor kidney and thyroid function. Lamotrigine does not need routine blood-level monitoring. It does, though, have to be started at a low dose and increased very slowly, because of an FDA boxed warning about rare but serious skin reactions.
Side effects differ too. Lithium can cause weight gain, a fine tremor, and increased thirst. Lamotrigine is relatively weight-neutral and has a low rate of sexual side effects.
Pregnancy is another point, and both are clinician decisions. Lithium has been linked to a small increased risk of certain heart defects. Lamotrigine is often considered relatively more usable in pregnancy, though it is still a decision for a clinician.
Side effects compared
The two medications differ in their everyday side effects. Lithium can cause weight gain, a fine tremor, and increased thirst. Its narrow range between effective and toxic levels is the reason for regular blood tests. Lamotrigine is relatively weight-neutral and has a low rate of sexual side effects, but its slow dose increase exists because of the FDA boxed warning about rare but serious skin reactions.
Because of these differences, the monitoring also differs. Lithium needs regular blood tests for the drug level, kidney function, and thyroid function. Lamotrigine needs careful, slow dose increases instead. If a side effect is severe, or a new rash appears while taking lamotrigine, that is a prompt reason to contact a prescriber rather than to stop on your own.
Sleep, weight, and sexual effects
For sleep, weight, and sexual effects, the two differ in clear ways.
Lithium can cause weight gain, while lamotrigine is relatively weight-neutral. Lamotrigine has a low rate of sexual side effects. Both can affect sleep for some people. Weight and sexual effects are worth raising with a prescriber, because there are real options, including a dose change or a switch.
Why a clinician might choose one over the other
The choice follows a person's pattern of mood episodes.
A clinician might choose lithium when broad coverage including mania matters, and for its strong evidence, including for suicide prevention, in someone who can commit to regular blood monitoring. A clinician might choose lamotrigine when the depressive side of bipolar disorder is the main problem, and when a weight-neutral option that needs less blood monitoring is wanted. The two are also sometimes used together.
The bottom line
Lithium is the broad benchmark mood stabilizer with the strongest evidence, including for suicide prevention. Lamotrigine is especially good for bipolar depression and is often easier to tolerate. Neither is simply better. The choice depends on a person's pattern of mood episodes, and it is made with a prescriber.
Sources
This guide draws on current prescribing information and public health references. It is reviewed for clinical accuracy and updated as guidance changes.
- U.S. Food and Drug Administration. Lithium prescribing information.
- U.S. Food and Drug Administration. Lamotrigine prescribing information.
- MedlinePlus, U.S. National Library of Medicine.
- National Institute of Mental Health. Mental health medications.
Managing a medication needs a prescriber
Any psychiatric medication has to be started and adjusted by a clinician who can follow you over time. If you don't have a prescriber, our guides section explains the options, including in-person care and telepsychiatry, and how to choose between them.
This guide is for general education. It is not medical advice and is not a substitute for evaluation, diagnosis, or treatment by a qualified clinician. Never start, stop, or change a medication without talking to your prescriber. If you are in crisis or thinking about harming yourself, call or text 988 in the U.S. to reach the Suicide and Crisis Lifeline.