I just took 100 mg of lamotrigine on accident. What, if anything, could happen from this?

Side effects/allergy. Although rare, allergic reactions have occurred with lamotrigine: watch for rash, fever; swollen glands; painful sores in or around your eyes or mouth; difficulty breathing; swelling of your face, lips, tongue, or throat. Also: this drug may make you dizzy or drowsy or cause blurred vision. Do not drive, use machinery, or do any activity that requires alertness. Do not drink alcohol.