Lamotrigine (Lamictal) Rash

A lamotrigine rash is any new skin rash that appears while taking lamotrigine (Lamictal). Most turn out to be minor, but a small number become Stevens-Johnson syndrome or toxic epidermal necrolysis, which can be life-threatening. The FDA label is clear that nobody can reliably predict which rash will become serious, and that lamotrigine should ordinarily be stopped at the first sign of rash unless the rash is clearly unrelated to the drug. That is why the safe rule is simple: any rash on lamotrigine means calling your prescriber the same day, and certain signs mean emergency care now.

When a rash is an emergency

Do not wait to see whether a rash settles on its own, and do not rely on a photo comparison online. A clinician needs to look at it.

What the boxed warning says

The Lamictal label opens with a boxed warning for serious skin rashes. The key points:

• Lamotrigine can cause serious rashes requiring hospital care and stopping treatment, including Stevens-Johnson syndrome. Rare cases of toxic epidermal necrolysis and rash-related deaths have been reported.
• In the label, serious rash occurred in about 0.3% to 0.8% of children and teens aged 2 to 17 and about 0.08% to 0.3% of adults. The rate is higher in young people.
• Benign rashes also happen with lamotrigine, but it is not possible to predict reliably which rashes will prove serious.
• Lamotrigine should ordinarily be stopped at the first sign of rash, unless the rash is clearly not drug related. Even stopping may not prevent a rash from becoming life-threatening or permanently disfiguring.

Put simply, serious rash is rare, but when it happens it can be severe, and the early stages can look ordinary.

When rashes tend to appear

According to the label, nearly all life-threatening rashes have started within 2 to 8 weeks of beginning lamotrigine. That is the period when the dose is being built up.

Isolated cases have occurred after longer treatment, such as six months. The label warns that time on the medicine cannot be relied on to predict risk. Being on lamotrigine for a while lowers the odds, but it does not make a new rash safe to ignore.

Restarting after a break can reset some of that risk, which is why the restart rule below exists. How lamotrigine is used more broadly is covered in lamotrigine for bipolar disorder.

Who is at higher risk

The boxed warning names these factors, and notes that serious rashes have also happened without any of them:

The HLA-B*1502 item is new. The FDA added it to the Lamictal boxed warning in October 2025, and the FDA's pharmacogenomic table now lists HLA-B in the lamotrigine label's boxed warning. The label says to weigh risks and benefits in people known to carry the variant, and notes that genetic screening has important limits. It is not a test that clears anyone of rash risk. Gene testing is discussed in genetic testing and bipolar medication.

Warning signs to watch for

The Medication Guide tells people to call their healthcare provider right away for:

• A skin rash of any kind
• Blistering or peeling of the skin
• Hives
• Painful sores in the mouth or around the eyes

Lamotrigine can also cause serious reactions affecting the liver, blood cells or other organs, sometimes without a rash. The Medication Guide lists symptoms such as fever, frequent infections, severe muscle pain, swelling of the face, eyes, lips or tongue, swollen lymph glands, unusual bruising or bleeding, weakness, and yellowing of the skin or eyes. These need prompt medical attention too.

These first signs can be subtle, and recognizing them early is the reason for the same-day rule. Other medication side effects are covered in psychiatric medication side effects.

"Benign rash" and why self-triage is unsafe

Many people search for "benign lamotrigine rash" or rash pictures hoping to rule out a problem at home. The label's own wording is the reason not to: although benign rashes occur, it is not possible to predict reliably which will become serious.

• A rash that looks mild today can progress over hours to days.
• Photos online cannot show how a rash is changing, how it feels, or whether you have fever or mouth sores.
• Even clinicians sometimes need to examine a rash in person, or stop the drug as a precaution, before the picture is clear.

After an exam, the clinician decides whether lamotrigine continues. If it is stopped because of a rash, the mood plan still needs attention, because stopping a maintenance medicine can raise relapse risk. That conversation happens with your prescriber.

Restarting after a rash or a break

Two label rules apply:

• After a rash: lamotrigine should not be restarted in someone who stopped it because of a rash unless the potential benefits clearly outweigh the risks.
• After missed doses: if lamotrigine has been stopped long enough to leave the body, the starting schedule should be followed again rather than resuming the previous dose.

Don't restart at your old dose on your own; call the prescriber. They will say whether to resume or start the slow build-up again.

Lowering the risk, and teens

• Take lamotrigine exactly as prescribed during the build-up; do not speed it up even if you feel fine.
• Make sure every prescriber and pharmacist knows if you take valproate.
• Check that each refill is the right drug and strength, since look-alike names have caused errors.
• Know your prescriber's contact route before you start, so a same-day call is easy.

For teens, lamotrigine is not FDA-approved for bipolar disorder, and the serious rash rate is higher than in adults. Parents should know the warning signs too. See bipolar medication for teens.

At Willow & Stone

Willow & Stone provides outpatient, scheduled care and is not an emergency service, so a rash with blisters, sores or fever goes to 911 or an emergency room first. Dr. Stacey Forbes, PMHNP-BC, sees patients in Arlington, Texas, and by telehealth in Texas, New Mexico, Florida, Alaska, Arizona, Colorado and Washington, and medication options are discussed at your evaluation. See bipolar disorder treatment at Willow & Stone or the bipolar disorder guide.

Common Questions

Sources & Further Reading

• DailyMed: LAMICTAL (lamotrigine) prescribing information and Medication Guide (October 2025)
• FDA: Table of Pharmacogenomic Biomarkers in Drug Labeling
• NICE CG185: Bipolar disorder: assessment and management (last updated 2 September 2025)
• Poison Control (America’s Poison Centers): 1-800-222-1222
• Yatham LN et al. CANMAT and ISBD 2018 guidelines for the management of patients with bipolar disorder. Bipolar Disord 2018 (PMID 29536616)

This article is general education, not a diagnosis or advice for your situation. Do not start, stop, or change a medication without talking to the clinician who prescribes it; stopping a mood stabilizer suddenly can trigger relapse.