Lamictal Rash: Which Rashes Are Emergencies and What to Do

Which Lamictal rashes are emergencies?

Any new rash in the first weeks on Lamictal (lamotrigine) is a same-day call to your prescriber, and a rash with blistering, peeling skin, hives, painful sores in the mouth or around the eyes, fever, or swelling of the face or throat is an emergency. The FDA prescribing information for Lamictal carries a boxed warning for serious skin rashes that can require hospitalization, notes that nearly all life-threatening cases occurred within two to eight weeks of starting, and says the medicine should ordinarily be stopped at the first sign of rash unless the rash is clearly not drug related. Most rashes on lamotrigine turn out to be the harmless kind. The problem is that nobody can tell which kind it is by looking at it at home, so the rule is not "wait and see." The rule is call.

Why does lamotrigine carry a boxed warning for rash?

A boxed warning is the strongest safety statement the FDA puts on a medicine, and for lamotrigine it is about the skin. The boxed warning section of the Lamictal prescribing information describes rare but serious rashes, including Stevens-Johnson syndrome, and puts the rate of serious rash in adult trials at between 0.08% and 0.3%, with a higher rate in children. Those are small numbers. They are in a box because the outcome, when it happens, is severe, and because the risk is partly in the prescriber's and patient's hands.

The label names the factors that raise the risk: taking lamotrigine together with valproate (valproic acid or divalproex), starting at a higher dose than the label recommends, and raising the dose faster than the label's schedule. That last pair is the reason your first weeks on lamotrigine look the way they do, and it is covered below.

What does a serious rash look like compared with a harmless one?

The honest answer is that early on they can look alike, which is why the advice is to report any rash rather than to self-triage. What you can watch for is the company a rash keeps. The MedlinePlus patient information for lamotrigine says to call your doctor immediately for a rash, blistering or peeling of the skin, hives, itching, or painful sores in your mouth or around your eyes. The FDA label also describes a multiorgan hypersensitivity reaction, sometimes called DRESS, in which a rash comes with fever, swollen lymph nodes, or facial swelling, and it lists aseptic meningitis, with headache, fever, stiff neck, and sensitivity to light, among the reactions that need prompt attention.

A practical way to hold this: a plain rash is a same-day phone call, and a rash plus any of those extra features is an emergency room visit. If you cannot reach your prescriber the same day and the rash is spreading or changing, do not wait for a callback.

Why is the dose raised so slowly?

People starting lamotrigine often notice that the first prescription is a starter pack with a schedule that climbs over weeks. That is deliberate. The MedlinePlus information explains that the prescriber will start you on a low dose and increase it gradually, not more than once every one to two weeks, specifically because starting high or increasing quickly raises the chance of a serious rash. The FDA label lists exceeding the recommended starting dose or the recommended escalation as rash risk factors in their own right.

That schedule has two consequences worth knowing before you start. First, the medicine is not expected to do much in the earliest weeks, so a slow start is not a sign it is failing. Second, speeding the schedule up on your own, or taking two doses to make up for a missed one, undoes the main thing that keeps the early weeks safe. If you think the pace is wrong for you, that is a conversation with your prescriber, not a change to make yourself.

What happens if I stop and restart lamotrigine?

This is the part of the label that catches people out. The FDA prescribing information states that if lamotrigine has been stopped for more than five half-lives, the initial dosing recommendations should be followed again, which in plain terms means starting over at the beginning of the schedule rather than resuming the dose you were on. The rash risk is tied to how fast the dose is introduced, and a body that has been off the medicine for a stretch is, for this purpose, a body that has never had it.

So a bottle of leftover tablets after a week or two away is not a prescription to restart. For a single missed dose, MedlinePlus says to take it as soon as you remember unless it is almost time for the next one, and never to double up. For a longer gap, call before you take anything, and tell your prescriber how many days you missed; they will set the restart. There is more general guidance in our article on what to do after a missed dose of a psychiatric medication. Stopping lamotrigine abruptly is its own problem: MedlinePlus warns that your prescriber will usually lower the dose gradually, and that stopping suddenly can bring on seizures in people who take it for epilepsy. Never stop, start, or change a dose on your own; talk with your prescriber first.

What else should you tell your prescriber before starting?

Three things change how lamotrigine is handled, and all of them are on the label.

• Valproate. Taking valproic acid or divalproex with lamotrigine raises the serious rash risk, so your prescriber needs to know about it before the first dose, not after.
• Hormonal contraceptives. MedlinePlus notes that lamotrigine may decrease the effectiveness of hormonal contraceptives, and the FDA label says that estrogen-containing contraceptives can lower lamotrigine levels enough that the maintenance dose may need to change when the contraceptive is started or stopped. Starting, stopping, or switching birth control is a tell-your-prescriber event.
• A past rash on an epilepsy medicine. MedlinePlus lists a prior rash after lamotrigine or another anti-seizure medicine among the things that make a serious rash more likely.

What is lamotrigine used for in bipolar disorder?

Lamotrigine is an anti-seizure medicine that is also used as a mood stabilizer. The FDA label approves lamotrigine as maintenance treatment of bipolar I disorder, to delay the time until the next mood episode in adults who have been treated for an acute episode, and says treatment of an acute manic or mixed episode is not recommended. MedlinePlus puts it plainly: it increases the time between episodes, but is not effective during one.

That makes lamotrigine a between-episodes medicine, and it is one reason a prescriber may pair it with other treatment or choose a different medicine for an episode that is happening now. If you are weighing options, you can read about what starting lithium involves, and our overview of how bipolar disorder is evaluated and treated covers the bigger picture, including therapy. Comparisons like these explain how two medicines differ; they do not say which is better, because that depends on your history and your prescriber's judgment.

What other side effects should you expect?

Beyond the rash, the MedlinePlus information lists common side effects that include loss of balance or coordination, double or blurred vision, trouble concentrating, headache, drowsiness, dizziness, diarrhea or constipation, loss of appetite, nausea, dry mouth, and uncontrollable shaking. The FDA label also includes a class warning that anti-seizure medicines, lamotrigine among them, can increase the risk of suicidal thoughts or behavior, and asks patients and families to watch for new or worsening depression, unusual changes in mood or behavior, or thoughts of self-harm, and to report them right away.

If you or someone you know is thinking about suicide or is in crisis, call or text 988 to reach the 988 Suicide & Crisis Lifeline. It is free, confidential, and available around the clock. If someone is in immediate danger, call 911.

When should you call, and when should you go to the emergency room?

Call your prescriber the same day for any new rash, for a missed stretch of doses before you restart, for a new medicine or a change in birth control, and for mood changes that worry you or the people around you. Go to the emergency room, or call 911, for a rash with blistering, peeling, hives, mouth or eye sores, fever, or swelling of the face, lips, or throat, for trouble breathing or swallowing, for a severe headache with fever and a stiff neck, and for any thoughts of harming yourself.

MindVibe sees patients aged 13 and up, in person at offices in Texas and California and by telehealth, and the first-weeks check on a new mood stabilizer is the kind of follow-up that fits either. If you are starting one and want a second set of eyes on the plan, or you have not yet been evaluated, you can book a visit with a psychiatric provider who can walk through the options with you. Keep every follow-up visit in the first weeks; that is when the watching matters most.

This article is for educational purposes only and is not medical advice, a diagnosis, or a substitute for care from a licensed clinician. Never stop, start, or switch a medication on your own; talk with your prescriber. In a crisis, or if you are having thoughts of suicide, call or text 988 to reach the 988 Suicide & Crisis Lifeline, or go to the nearest emergency room.

Frequently asked questions

How soon after starting Lamictal can a rash appear?

The FDA label reports that nearly all life-threatening rashes occurred within two to eight weeks of starting, and the MedlinePlus patient information says the same window is when serious rashes usually develop. A rash can still appear later, so a new rash at any point on lamotrigine is worth a call. The early weeks are when to be most watchful.

Is every rash on lamotrigine dangerous?

No. Most rashes on lamotrigine are not the serious kind, but there is no reliable way to tell a harmless rash from the early stage of a serious one at home, which is why the FDA label says the medicine should ordinarily be stopped at the first sign of rash unless the rash is clearly not related to the drug. Let your prescriber make that call the same day, rather than waiting to see how it develops.

What if I stopped lamotrigine for a few days and want to restart?

Do not restart at your previous dose on your own. The FDA label states that if lamotrigine has been stopped for more than five half-lives, the initial dosing recommendations should be followed again, because the rash risk is tied to how fast the dose is introduced. Call your prescriber, tell them how many days you missed, and let them set the restart.

Can I take birth control pills with lamotrigine?

You can, but your prescriber needs to know. The MedlinePlus information notes that lamotrigine may decrease the effectiveness of hormonal contraceptives, and the FDA label says that estrogen-containing contraceptives can change lamotrigine levels enough that the dose may need adjusting when they are started or stopped. Mention any change in birth control at your next visit, before you make it if you can.

What does lamotrigine do for bipolar disorder?

According to the FDA label, lamotrigine is approved as maintenance treatment of bipolar I disorder, to delay the time until the next mood episode in adults who have already been treated for an acute episode. The label does not recommend it for treating an acute manic or mixed episode, and the MedlinePlus information says it is not effective for an episode that is already under way. It is a between-episodes medicine.

Does lamotrigine need blood tests?

The two things to watch in the first weeks are the ones the sections above describe: any new rash, and your full medicine list, especially valproate and hormonal birth control, which your prescriber needs to know about. Your prescriber decides what monitoring applies to you, and may order blood work for other reasons, so ask at your first visit what checks to expect.