Lamotrigine prescribing information has a black box warning about life-threatening skin reactions, including Stevens–Johnson syndrome, DRESS syndrome and toxic epidermal necrolysis.[24] The manufacturer states that nearly all cases appear in the first 2 to 8 weeks of therapy and if medication is suddenly stopped then resumed at the normal dosage. Patients should seek medical attention for any unexpected skin rash, as its presence is an indication of a possible serious or even deadly side-effect of the drug. Not all rashes that occur while taking lamotrigine progress to SJS or TEN. Between 5 to 10% of patients will develop a rash, but only one in a thousand patients will develop a serious rash. It is thought that one in 50,000 exposed patients may die from the rash.[citation needed] Rash and other skin reactions are more common in children, so this medication is often reserved for adults.

There is also an increased incidence of these eruptions in patients who are currently on, or recently discontinued a valproate-type anticonvulsant drug, as these medications interact in such a way that the clearance of both is decreased and the effective dose of lamotrigine is increased.

As of December 2010, lamotrigine carries an FDA black box warning for aseptic meningitis.[25]

Side-effects such as rash, fever, and fatigue are very serious, as they may indicate incipient Stevens–Johnson syndrome, toxic epidermal necrolysis, DRESS syndrome or aseptic meningitis.[25]

Other side-effects include loss of balance or coordination, double vision, crossed eyes, pupil constriction, blurred vision, dizziness and lack of coordination, drowsiness, insomnia, anxiety, vivid dreams or nightmares, dry mouth, mouth ulcers,[citation needed] memory and cognitive problems, mood changes, runny nose, cough, nausea, indigestion, abdominal pain, weight loss, missed or painful menstrual periods, and vaginitis. The side-effect profile is different for different patient populations.[25]

Lamotrigine has been associated with a decrease in white blood cell count (leukopenia).[26] Lamotrigine does not prolong QT/QTc in TQT studies in healthy subjects

My husbands neuro gave him this last week and his headaches are completely gone. This is a medicine made for seizures and bipolar and not FDA approved but has been known to help some headache sufferers.