Lamotrigine is used to treat certain types of seizures in patients who have epilepsy or Lennox-Gastaut syndrome (a disorder that causes seizures and often causes developmental delays). Lamotrigine is also used to increase the time between episodes of depression, mania (frenzied or abnormally excited mood), and other abnormal moods in patients with bipolar I disorder (manic-depressive disorder; a disease that causes episodes of depression, episodes of mania, and other abnormal moods). Lamotrigine has not been shown to be effective when people experience the actual episodes of depression or mania, so other medications must be used to help people recover from these episodes. Lamotrigine is in a class of medications called anticonvulsants. It works by decreasing abnormal excitement in the brain. Lamotrigine comes as a regular tablet and a chewable dispersible (can be chewed or dissolved in liquid) tablet to take by mouth. It is usually taken once or twice a day. It is sometimes taken once every other day at the beginning of treatment. Follow the directions on your prescription label carefully and ask your doctor or pharmacist to explain any part you do not understand. There are other medications that have names similar to the brand name for lamotrigine. You should be sure that you receive lamotrigine and not one of the similar medications each time you fill your prescription.