lamotrigine

Mood stabilizer

Brands: Lamictal

Last reviewed 2025-09-26

Reviewed by PsychMed Editorial Team.

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Quick answers

What is lamotrigine?
Lamotrigine (Lamictal) is a phenyltriazine anticonvulsant repurposed as a weight-neutral mood stabilizer that prevents bipolar depressive relapse without appreciable metabolic or cognitive burden.
What is Lamictal?
Lamictal is a brand name for lamotrigine.
What is Lamictal (lamotrigine) used for?
Label indications include: Maintenance treatment of bipolar I disorder.
What drug class is Lamictal (lamotrigine)?
Mood stabilizer.
What is the mechanism of action of Lamictal (lamotrigine)?
Voltage-gated sodium channel blocker that reduces glutamate release and stabilizes neuronal membranes; mood stabilizer with antidepressant properties.
What strengths does Lamictal (lamotrigine) come in?
Immediate-release tablets 25–200 mg with branded titration starter packs that map the six-week escalation.
Is Lamictal (lamotrigine) a controlled substance?
No — it is not scheduled as a controlled substance under U.S. federal law.

Snapshot

Class: Mood stabilizer
Common US brands: Lamictal
Therapeutic drug monitoring not routinely recommended.
Last reviewed: 2025-09-26

Clinical Highlights

Lamotrigine (Lamictal) is a phenyltriazine anticonvulsant repurposed as a weight-neutral mood stabilizer that prevents bipolar depressive relapse without appreciable metabolic or cognitive burden. Lamotrigine mechanism of action blocks voltage-gated sodium channels and dampens glutamate release, giving it antidepressant polarity strength with minimal antimanic effect; it is often combined with lithium, valproate, or an SGA when broader mania coverage is needed.

The FDA approved lamotrigine in 2003 for maintenance treatment of bipolar I disorder; because it provides little protection against acute mania, clinicians usually combine it with lithium, valproate, or an atypical antipsychotic for sustained hypomanic prophylaxis.
Contemporary CANMAT/ISBD and NICE guidelines endorse lamotrigine as a first-line option for depressive polarity maintenance when slow titration is acceptable and metabolic neutrality, pregnancy planning, or antidepressant sensitivity are priorities.
The compare tool and lamotrigine evidence feed support side-by-side review of maintenance choices (metabolic profile, titration speed, and bipolar outcomes). The bipolar disorder hub can support follow-up planning.
Relied on for bipolar depression prevention, postpartum transitions, and patients prioritizing weight neutrality; typically paired with broader antimanic coverage because lamotrigine has minimal impact on mania.
Maintenance treatment of bipolar I disorder (FDA 2003)
Generic: All core formulations are available generically in the United States.

Dosing & Formulations

Immediate-release tablets 25–200 mg with branded titration starter packs that map the six-week escalation. Chewable/dispersible 2–25 mg and orally disintegrating tablets 25–200 mg for flexible dosing or adherence support.

Extended-release tablets 25–300 mg administered once daily.
Standard regimen (no valproate or strong inducers): 25 mg once daily for weeks 1–2, 50 mg once daily weeks 3–4, 100 mg once daily week 5, then 200 mg/day from week 6 onward with optional increases to 300–400 mg based on response.
With valproate: 25 mg every other day weeks 1–2, 25 mg once daily weeks 3–4, 50 mg once daily week 5, then 100 mg/day (maximum 200 mg/day) from week 6.
With enzyme inducers (carbamazepine, phenytoin, phenobarbital, primidone, rifampin) and without valproate: 50 mg once daily weeks 1–2, 100 mg/day in two divided doses weeks 3–4, 200 mg/day week 5, 300 mg/day week 6, and 400 mg/day thereafter as tolerated.
Therapeutic drug monitoring is sometimes used in pregnancy, postpartum, or when strong inducers/inhibitors are introduced; trough levels are typically checked after dose changes and interpreted alongside clinical response.

Monitoring & Risks

Boxed warning: Serious skin reactions including Stevens-Johnson syndrome/toxic epidermal necrolysis—risk highest in the first 8 weeks, with rapid titration, or in the presence of valproate; label language generally calls for discontinuation if rash occurs unless another cause is clear. Headache: Most frequently reported; often improves after titration.

Dizziness/ataxia: Dose-related; slower titration or bedtime dosing can mitigate.
Diplopia/blurred vision: Dose adjustments may be needed if persistent.
Nausea: Usually transient; taking with food can help.
Insomnia: Morning dosing and sleep hygiene reinforcement are common adjustments.

Drug Interactions

Valproate inhibits lamotrigine glucuronidation and roughly doubles serum concentrations—titration and maintenance doses are typically halved, and toxicity monitoring is increased. Potent enzyme inducers (carbamazepine, phenytoin, phenobarbital, primidone, rifampin) increase clearance—an accelerated titration schedule is often used, and higher maintenance doses may be needed.

Estrogen-containing contraceptives or hormone therapy can increase clearance by 40–60%; dose adjustments are often needed when estrogen is started or stopped.
Atazanavir/ritonavir and lopinavir/ritonavir reduce lamotrigine exposure—clinical response is monitored and dose increases may be considered.
Prior serious rash with aromatic antiepileptics (e.g., carbamazepine, oxcarbazepine) heightens rash risk; counseling often emphasizes rash recognition and risk–benefit tradeoffs.

Practice Notes

Titration packs or digital reminders are commonly used to support adherence throughout the six-week escalation. Education commonly covers rash, fever, swollen glands, or flu-like symptoms, with urgent evaluation for concerning presentations.

Therapeutic drug monitoring is not routine but can guide dosing in pregnancy, postpartum, or when strong inducers/inhibitors are introduced or withdrawn.
If therapy is interrupted for more than five consecutive days, titration is typically restarted from the beginning to lower serious rash risk.
Contraceptive plans and pregnancy intentions are often reviewed; doses may need adjustment and mood symptoms are followed as clearance changes during pregnancy and after delivery.
The compare tool tool](https://psychmed.org/compare?meds=lamotrigine,lithium,quetiapine) can help weigh lamotrigine against lithium and quetiapine when balancing metabolic neutrality with acute mania protection.

References

Lamotrigine tablets — Prescribing Information — DailyMed (2024)
The CANMAT and ISBD Guidelines for the Management of Patients With Bipolar Disorder: 2021 Update — Bipolar Disorders (2021)Guidelinebipolarclinical
Bipolar disorder: assessment and management (NICE guideline CG185) — National Institute for Health and Care Excellence (2020)
Lamotrigine Augmentation IN Treatment Resistant Bipolar Depression: A Step BD Randomized Trial — American Journal of Psychiatry (2006)
Lamotrigine in mood disorders: a systematic review — Annals of Clinical Psychiatry (2018)
FDA safety communication: lamotrigine and hemophagocytic lymphohistiocytosis
AGNP Consensus Guidelines for Therapeutic Drug Monitoring in Neuropsychopharmacology — Pharmacopsychiatry (2018)