The 2021 lamotrigine heart warning applies to a specific group, not everyone
It rests on lab testing plus reasoning about who is vulnerable, not on a trial that counted deaths.
Top of the evidence hierarchy, independently funded. how we score evidence
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.
What it is FDA approved for
Read off the label. Trial duration and approval year are shown only where they were recorded — never inferred.
- Maintenance treatment of bipolar I disorder (to delay time to occurrence of mood episodes, after acute stabilization)
- Epilepsy, adjunctive therapy (partial-onset seizures, primary generalized tonic-clonic seizures, Lennox-Gastaut syndrome; ages 2+)
- Epilepsy, conversion to monotherapy for partial-onset seizures (ages 16+)
Source
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)
Regulator or national health body
How this was scored
- Study design
- Regulatory safety determination
- Funding
- No external funding
- Published in
- Regulator or national health body
- Sample size
- not recorded
- Preregistered
- No
- Conflicts disclosed
- Yes
- Independent of proponent
- Yes
- Retracted
- No
Read the full scoring rubric, including what it can't tell you.
Published August 5, 2026. Last verified August 19, 2026.
Questions
How strong is the evidence behind this?
Resolv rates this source "gold standard". Top of the evidence hierarchy, independently funded. It scores 86 out of 100 on our published rubric. The score is calculated from recorded facts about the source — study design, funding, publication venue, sample size, preregistration — not typed in by an editor.
What is the source for this?
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). Published in: Regulator or national health body. The full source is linked on this page so you can read it yourself.
Who paid for this research, and does that matter?
Study design: Regulatory safety determination. Funding: No external funding. The researchers were independent of whoever benefits from the result. Industry sponsorship is one of the most reliably measured biases in medicine, which is why funding carries real weight in the score rather than sitting in a footnote.
Is lamotrigine (Lamictal) FDA approved?
Yes — FDA approved for Maintenance treatment of bipolar I disorder (to delay time to occurrence of mood episodes, after acute stabilization), Epilepsy, adjunctive therapy (partial-onset seizures, primary generalized tonic-clonic seizures, Lennox-Gastaut syndrome; ages 2+), Epilepsy, conversion to monotherapy for partial-onset seizures (ages 16+). Approval is for a specific indication, not for everything the drug is prescribed for.
Is this medical advice?
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.
This is information to bring to your prescriber, not medical advice and not a reason to change anything on your own. Nothing here is an instruction to stop or reduce a medication. If you are in crisis, call or text 988.