One of the less common side effects of Lamictal is weight loss. It is considered to be one of the less serious side effects and is not common, according to Drugs.com.
According to a study published in The American Journal of Psychiatry, there was no significant difference in weight loss between patients taking Lamictal and those taking a placebo. It's not usually necessary to seek medical attention if a patient experiences weight loss associated with taking Lamictal. A physician may be able to suggest methods of alleviating any discomfort related to excessive weight loss and should be consulted if the problem persists or there are any questions.