lamotrigine (Lamictal)

How long the trials actually ran

The longest trial behind the lamotrigine approval ran 78 weeks (about 18 months).

The gap between how long the trials ran and how long people actually take these medications is the single most important thing on this page. It is not evidence that longer use is unsafe or ineffective. It is evidence that longer use was not what got tested.

How many Americans take lamotrigine

Survey-based federal estimates, published with a lag of about two years. They count prescriptions filled, not outcomes.

12,624,285

prescriptions in the United States (2024)

2,474,524

people filling them (2024)

Prescriptions are down 1% since 2014. Whatever you decide about lamotrigine, you are deciding alongside about 2,474,524 other people this year.

Source: ClinCalc DrugStats (Medical Expenditure Panel Survey (MEPS), Agency for Healthcare Research and Quality), CC BY-SA 4.0, release 2026.08.

What people report to the FDA about lamotrigine

71,378

reports mentioning lamotrigine, all time

57,748

filed as serious (a report-level flag covering every drug and outcome in the report)

Source: FDA Adverse Event Reporting System (FAERS), via openFDA, data through 2026-07-30.

Known interactions, from the label

The FDA label’s interactions section, verbatim. A pharmacist checking your actual medication list beats any published list — including this one.

FDA label for lamotrigine, effective August 13, 2026 — DailyMed.

Who pays for lamotrigine

Two claims datasets and one survey, covering different populations with different instruments — they cannot be reconciled by arithmetic, and where their sum crowds the all-payer estimate, that is a finding about the estimates rather than a percentage.

Medicare Part D

Read the under-65 group correctly before the numbers: Medicare before 65 means the disabled and dual-eligible population — among the sickest, highest-need people in the program — and reading their utilization as typical adult use would be a category error. The beneficiary total sums brand-level rows, so treat it as an upper bound on distinct people. 679,206 beneficiaries filled 4,395,266 claims in 2024 — 359,509 aged 65 and over, and 319,697 under 65.

Medicaid

At least 4,511,361 prescriptions in 2024 — a floor, because 193 of 1,409 national data rows are suppressed for privacy and contribute zero. Medicaid covers more children than any insurer in the country and publishes no age split — how much of this number is pediatric use is not knowable from public data.

All payers (survey estimate)

The MEPS-based estimate above puts the whole country at 12,624,285 prescriptions and 2,474,524 people in 2024. Subtracting the public programs from it would produce a number for everyone else — and we do not print that number, because subtracting a survey from claims counts manufactures precision that does not exist.

The population nobody counts

The commercially insured working-age adult — statistically, the likeliest person to be reading this page — is the one population with no public per-drug count anywhere. Private claims data exists and is sold, but nothing a patient can check is published. For children the record is thinner still: no public source counts pediatric use of lamotrigine specifically; the closest the public record comes is condition-level treatment rates for children, which we have traced for one condition in how childhood ADHD got counted.

Sources: Medicare Part D Prescribers — by Geography and Drug, data.cms.gov, National rows, data year 2024 (published with ~17-month lag). Medicaid State Drug Utilization Data 2024, data.medicaid.gov, national aggregate rows. Retrieved 2026-09-01.

The approval, step by step

1. Step 1

   What the approval was actually based on

   Which studies did the FDA rely on, how long did they run, and who was in them?

   The effectiveness of LAMICTAL in the maintenance treatment of bipolar I disorder was established in 2 multicenter, double-blind, placebo-controlled trials in adult patients (aged 18 to 82 years) who met DSM-IV criteria for bipolar I disorder... Patients with a CGI-severity score of 3 or less maintained for at least 4 continuous weeks, including at least the final week on monotherapy with LAMICTAL, were randomized to a placebo-controlled double-blind treatment period for up to 18 months.

   FDA-approved labelling, 14 CLINICAL STUDIES 14.2 Bipolar Disorder — read the label on DailyMed

   Our reading

   This is the strongest duration record in the directory and it deserves saying plainly: the randomised period ran up to eighteen months, not three to ten weeks, because the claim itself is about maintenance. But read the second sentence again. Everyone was put on lamotrigine first, for eight to sixteen weeks, and only those who had already responded and stayed well for four weeks were randomised — 1,305 people entered that run-in and 471 reached randomisation. So the trials answer "does it keep working for people it already works for?", not "will it work for me?". Two further things worth knowing: the label states effectiveness in acute episodes has not been established and acute mania is not recommended, so if you were started on it while acutely unwell you are outside the studied use; and lamotrigine had already been on the market for epilepsy since 1994, which is why its serious-rash boxed warning predates this indication rather than arriving after it.

2. Step 2

   The approval

   When was it approved, under what application, and by whose review?

   Approved

   June 20, 2003

   Application

   NDA020241 SUPPL-17

   Review

   STANDARD

   Original sponsor

   GlaxoSmithKline

   Holds it now

   GlaxoSmithKline LLC

   Label submissions since

   50

   Source: openFDA Drugs@FDA, original application ORIG-1

3. Step 3

   What was added after it was on the market

   Which warnings arrived only after millions of people were already taking it?

   • A new life-threatening warning was added to lamotrigine in 2018

     15 years after approval

     In June 2018 the FDA added a subsection to the lamotrigine label that had not existed before: hemophagocytic lymphohistiocytosis, or HLH. It is a syndrome of runaway immune activation, and the label calls it life-threatening, with high mortality if it is not recognised early and treated. Reported signs include fever, rash, an enlarged liver or spleen, swollen lymph nodes, neurological symptoms, low blood counts, and abnormal liver and clotting results. Symptoms have been reported 8 to 24 days after starting the medication.

     Two things about this are worth sitting with. It arrived in 2018, and lamotrigine was approved for bipolar maintenance in 2003 and has been marketed since 1994 — this was not in the approval package. It came from people taking the drug afterwards. And the label gives no rate for it. That is not sloppiness: reports like these arrive voluntarily from a population of unknown size, so a frequency cannot honestly be calculated. What the label does say is that it has occurred, in both children and adults, across the conditions lamotrigine is used for.

     This is not a reason to stop, and stopping lamotrigine abruptly carries its own risk. It is a reason to know what the first month should not look like.

     Worth asking

     What exactly should I watch for in the first three or four weeks, who do I call if I get a fever and a rash at the same time, and is there anything in my history that makes this more likely.

     LAMICTAL (lamotrigine) safety-related labeling change, 27 June 2018 (SUPPL-57): Warnings and Precautions 5.2, Hemophagocytic Lymphohistiocytosis — new subsection added — U.S. Food and Drug Administration (2018)

   • The 2021 lamotrigine heart warning applies to a specific group, not everyone

     18 years after approval

     On 31 March 2021 the FDA announced a potential increased risk of heart rhythm problems with lamotrigine in people who have heart disease. The FDA had required the manufacturer to run laboratory studies after receiving reports of abnormal ECG findings and, in some cases, chest pain, loss of consciousness and cardiac arrest. Those studies showed lamotrigine behaves like a Class IB antiarrhythmic drug at concentrations people actually reach — it blocks sodium channels in heart muscle.

     The qualifier in the label is the whole point. In a thorough QT study in healthy individuals, therapeutic doses did not slow ventricular conduction. The concern is a defined group: people with clinically important structural or functional heart disease — heart failure, valvular or congenital heart disease, conduction system disease, ventricular arrhythmias, channelopathies such as Brugada syndrome, significant ischaemic heart disease, or multiple risk factors for coronary artery disease. In those people the label says lamotrigine could widen the QRS and induce a proarrhythmia that can lead to sudden death. Taking other sodium channel blockers alongside it may add to that.

     So this is a warning built on in vitro findings and on who is plausibly vulnerable, not on an outcome trial. That cuts both ways. It is not evidence of harm in the general population, and it is not something to wave off if you have a heart condition. The label's instruction is to weigh the expected benefit against that risk for the individual patient.

     Worth asking

     Do I have a heart condition or risk factor that puts me in the group this is about, has anyone done an ECG since I started this, and does anything else I take block sodium channels.

     Studies show increased risk of heart rhythm problems with seizure and mental health medicine lamotrigine (Lamictal) in patients with heart disease — U.S. Food and Drug Administration (2021)

4. Step 4

   What independent research has found since

   What has been learned by people who were not selling it?

   • Lamotrigine in the maintenance treatment of bipolar disorder

     18 years after approval

     Across 11 trials with 2,314 participants, lamotrigine lowered the chance of a mood recurrence compared with placebo (risk ratio 0.67 for manic recurrence) and caused fewer side effects than lithium, but manic episodes were about twice as likely on lamotrigine as on lithium.

     Worth asking

     Since lamotrigine is weaker than lithium at preventing manic episodes, what is our plan if I start noticing early manic symptoms?

     Lamotrigine in the maintenance treatment of bipolar disorder — Hashimoto Y, et al. (2021)

   • Identifying the incidence of rash, Stevens-Johnson syndrome and toxic epidermal necrolysis in patients taking…

     14 years after approval

     Across 122 randomized trials with 18,698 patients taking lamotrigine, 8.3% developed some skin reaction, while Stevens-Johnson syndrome or toxic epidermal necrolysis occurred in 8 patients (0.04%, about 1 in 2,300).

     Worth asking

     What early rash signs should make me stop lamotrigine and contact you the same day?

     Identifying the incidence of rash, Stevens-Johnson syndrome and toxic epidermal necrolysis in patients taking lamotrigine: a systematic review of 122 randomized controlled trials — Bloom R, Amber KT (2017)

   • Comparative efficacy and tolerability of pharmacological treatments in the maintenance treatment of bipolar disorder:…

     11 years after approval

     In a network meta-analysis of 33 maintenance trials covering 6,846 patients, lamotrigine prevented relapse better than placebo and was among the best-tolerated options, but the authors concluded lithium should remain first-line because it prevents both manic and depressive relapse with better-quality evidence.

     Worth asking

     Was lithium considered before choosing lamotrigine to prevent my relapses, and what made lamotrigine the better fit for me?

     Comparative efficacy and tolerability of pharmacological treatments in the maintenance treatment of bipolar disorder: a systematic review and network meta-analysis — Miura T, et al. (2014)

   • Someone finally checked the lamotrigine heart warning against real patients

     22 years after approval

     The FDA's 2021 warning about lamotrigine and heart rhythm rested on laboratory work and on reasoning about who was plausibly vulnerable. It did not rest on a study that counted what happened to people. In 2025 an NIH-funded group did that study.

     Using a large health-insurance claims database, they compared adults starting lamotrigine against adults starting commonly prescribed alternatives, in three groups: bipolar disorder, partial seizures, and generalised tonic-clonic seizures. Everyone was free of arrhythmia for six months beforehand. In the bipolar group — 153,852 on lamotrigine against 213,593 on alternatives — ventricular tachycardia occurred in 0.79% over one year against 0.68%, a hazard ratio of 1.33 (95% CI 1.12 to 1.57).

     Both numbers deserve to be read. A 33% relative increase sounds serious. The same finding stated as an absolute difference is 0.11 percentage points, which is roughly one additional case per 900 people per year. Neither framing is the honest one on its own.

     Two cautions. The signal reached statistical significance only in the bipolar group; in both seizure groups the confidence intervals crossed 1, which is what you would expect either from a genuinely small effect in a smaller sample or from confounding. And this is claims data — people prescribed lamotrigine differ from people prescribed the alternatives in ways a database cannot fully adjust for.

     Worth asking

     Does my own heart history put me in the group the FDA warning was written about, and if it does, does this change anything about monitoring.

     Association of ventricular arrhythmias with lamotrigine: an observational cohort study — Radwanski P, et al. (2025)

   • Lamotrigine for treatment of bipolar depression: independent meta-analysis and meta-regression of individual patient…

     6 years after approval

     Pooling individual data from 1,072 patients in five trials, somewhat more people responded to lamotrigine than placebo in bipolar depression (risk ratio 1.27 on the Hamilton scale), a modest effect that was larger in severely depressed patients.

     Worth asking

     My depression is on the milder side — is lamotrigine alone likely to be enough for me, or should we plan to combine it with something else?

     Lamotrigine for treatment of bipolar depression: independent meta-analysis and meta-regression of individual patient data from five randomised trials — Geddes JR, Calabrese JR, Goodwin GM (2009)

   • A pooled analysis of 2 placebo-controlled 18-month trials of lamotrigine and lithium maintenance in bipolar I disorder

     1 year after approval

     In 638 patients randomized after stabilization, lamotrigine roughly doubled the time to the next mood episode versus placebo (median 197 vs 86 days), working mainly against depressive relapse while lithium worked mainly against mania.

     Worth asking

     If my episodes tend to be depressive rather than manic, does that make lamotrigine a better long-term fit for me than lithium?

     A pooled analysis of 2 placebo-controlled 18-month trials of lamotrigine and lithium maintenance in bipolar I disorder — Goodwin GM, et al. (2004)

5. Step 5

   What still is not known

   Which questions you might reasonably have has nobody answered yet?

   • The enrichment design excludes everyone who did not tolerate or respond to lamotrigine in the run-in. What is the benefit for an unselected patient starting today?
   • Eighteen months is the longest evidence here, and maintenance is often lifelong. What happens in year five?
   • Around 30% of participants had rapid-cycling bipolar disorder, but the trials were not designed to answer whether it helps that group specifically.
   • The combined analysis found the benefit "more robust for depression" than for mania. For a drug prescribed as a mood stabiliser, which pole is it actually stabilising?