The short answer: Lamictal (lamotrigine) can cause Stevens-Johnson syndrome and toxic epidermal necrolysis, rare skin reactions that can kill. The FDA label puts serious rash at about 0.08% to 0.3% of adults and 0.3% to 0.8% of children aged 2 to 17. Nearly all life-threatening cases start within 2 to 8 weeks of the first dose. The risk rises when the starting dose or the pace of increase is exceeded, which is why the dose climbs so slowly.
What does the Lamictal boxed warning actually say?
A boxed warning is the strongest safety statement the FDA puts on a prescription label. The current Lamictal prescribing information on DailyMed opens with "WARNING: SERIOUS SKIN RASHES." It states that Lamictal "can cause serious rashes requiring hospitalization and discontinuation of treatment."
The rashes named include Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). The Medication Guide lists blistering or peeling skin and painful sores in the mouth or around the eyes as possible first signs. The label also reports rare rash-related deaths in worldwide postmarketing experience, though too few to estimate a precise rate.
Two more points in the box matter for patients. Benign rashes also occur, and no one can reliably predict which rash will become serious. So the label tells prescribers to stop lamotrigine "at the first sign of rash, unless the rash is clearly not drug related." It adds that stopping may not prevent a rash from becoming life threatening or permanently disfiguring.
This is not unique to lamotrigine. The European EuroSCAR case-control study of 379 validated cases found a strong association between lamotrigine and SJS/TEN (relative risk above 14), alongside older drugs like carbamazepine and phenytoin. Risk in that study was restricted to the first few weeks of taking a drug.
How common is a serious rash on lamotrigine?
Rare, but not so rare that it can be ignored. Section 5.1 of the label gives these figures for rash serious enough to require hospitalization and stopping the drug:
- Adults with epilepsy: 0.3% (11 of 3,348) in premarketing clinical trials.
- Adults in bipolar and other mood disorder trials: 0.08% (1 of 1,233) on lamotrigine as initial monotherapy and 0.13% (2 of 1,538) as add-on therapy. No deaths occurred in these trials.
- Children aged 2 to 17: approximately 0.3% to 0.8% in a prospectively followed cohort. One rash-related death occurred among 1,983 children with epilepsy taking it as add-on therapy.
Put another way, the adult bipolar trial rate works out to roughly 1 serious rash per 1,000 people. Lamotrigine is approved in the US for maintenance treatment of bipolar I disorder in adults only, so the pediatric figures come from epilepsy use. A pooled analysis of two international studies in children under 15 still found lamotrigine strongly associated with SJS and TEN.
Who is at higher risk, according to the label?
Besides age, the current label lists four factors that may raise the risk or severity of rash:
- Taking valproate (Depakote or Depakene). In adult epilepsy trials, 1% (6 of 584) of patients on lamotrigine plus valproate were hospitalized for rash, versus 0.16% (4 of 2,398) without valproate. In children, the rates were 1.2% versus 0.6%. Valproate slows the breakdown of lamotrigine, which raises its level in the blood.
- Exceeding the recommended starting dose.
- Exceeding the recommended dose escalation, meaning raising the dose faster than the schedule.
- Carrying the HLA-B*1502 gene variant. Studies in people of certain Asian ancestry, such as Han Chinese and Thai patients, suggest about 2 to 3 times higher risk of SJS/TEN. The label warns that genotyping has important limitations and never replaces clinical vigilance.
The label also notes a possibly higher risk in people with a past allergy or rash from other seizure medicines. Cases have still occurred without any of these factors. Our guide to mood stabilizers covers how lamotrigine fits alongside lithium and valproate.
Why is the dose raised so slowly?
Because the two risk factors you can control are both about dose. The label says the rash risk "is increased by both exceeding the recommended initial dose of LAMICTAL and exceeding the recommended dose escalation." It concludes "it is important that the dosing recommendations be followed closely."
The practical result is a low start and gradual steps. MedlinePlus, the NIH patient drug guide, explains that your doctor will increase the dose "not more than once every 1 to 2 weeks." Lamictal Starter Kits package the first 5 weeks of doses and are "intended to help reduce the potential for rash," per the label. The exact schedule depends on your other medicines, since valproate and drugs like carbamazepine or estrogen-containing birth control change lamotrigine levels.
This slow build is also why lamotrigine is not used for acute mania. The label says treatment of acute manic or mixed episodes is not recommended. Follow the schedule your prescriber gives you, and do not speed it up because you feel impatient or low.
What happens if you stop and need to restart?
A gap can put you back at the start of the schedule. The label says that if lamotrigine has been stopped for more than 5 half-lives, "it is recommended that initial dosing recommendations and guidelines be followed." The longer the gap, the more the prescriber should consider restarting low. Half-life varies with your other medicines, so the safe cutoff is not the same for everyone.
The danger is resuming your full old dose after days off. That is effectively exceeding the starting dose, one of the named risk factors. If you run out or stop for any reason, call your prescriber before taking your next pill. Stopping suddenly carries its own risk, and gaps are common during periods of stress or disrupted routine.
Restarting after a lamotrigine rash is a separate question. The label recommends not restarting in people who stopped because of rash "unless the potential benefits clearly outweigh the risks." Small studies describe rechallenge after mild rash, but that decision belongs to a specialist.
What should you do if a rash appears?
The Lamictal Medication Guide tells patients to call their provider right away for any of these:
- A skin rash
- Blistering or peeling of the skin
- Hives
- Painful sores in the mouth or around the eyes
It adds that "there is no way to tell if a mild rash will become more serious," and a provider should examine you. Fever or swollen lymph glands also need prompt attention. The label says those can be early signs of a multiorgan reaction called DRESS even when no rash is visible.
In April 2018 the FDA added a second immune warning. Its Drug Safety Communication (archived copy) described hemophagocytic lymphohistiocytosis (HLH), a rare runaway immune reaction. The agency identified eight cases worldwide since 1994, and one patient died. HLH typically presents as persistent fever, usually above 101°F. The label says symptoms appeared within 8 to 24 days of starting.
Blistering, peeling, or mouth and eye sores with fever warrant emergency care. Coping with a sudden medication stop can shake mood stability, and mental.md covers broader mental health support.
The bottom line
Lamictal carries a boxed warning because it can cause SJS and TEN, which can be fatal. Serious rash is uncommon, about 1 in 1,000 adults in bipolar trials, and higher in children. Most dangerous rashes start in weeks 2 to 8. Taking valproate, starting too high, raising the dose too fast, and certain genes all raise the risk. Follow your prescriber's titration exactly, call before restarting after a gap, and treat any new rash as urgent.
Last updated: September 2026. This article is for informational purposes only and does not constitute medical advice. Do not start, stop, restart, or change your lamotrigine dose without talking to your prescriber, and seek urgent care for any rash with blistering, sores, or fever.