The main difference is how the medication, oxcarbazepine, is released into your body. The regular version releases the medicine quickly, while the extended-release (XR) version releases it slowly over 24 hours to maintain stable levels. Taking the regular version instead of the prescribed XR version is generally not an immediate emergency, but it can cause fluctuations in your blood levels. This might increase mild side effects like dizziness, or make the medication less effective at certain times of the day. Please do not panic or stop your medication. Contact your doctor or pharmacist promptly so they can guide you on safely transitioning back to your prescribed XR formulation.