 Hi, this is Dr. Pramod Krishnan. I'm a consultant neurologist at Manipal Hospital, Bangalore. I specialize in epilepsy. The most important reason why seizures occur while on medication is missing the medicine. When this happens, a patient may get a similar seizure as before or very often even more severe seizures. Another reason could be lack of sleep and not taking meals regularly. Use of alcohol can be another trigger for seizures. Blood chemical abnormalities like low glucose, low sodium can also trigger seizures even while on medications. Another important factor is the use of other medicines along with anti-epilepsy medicines. Some common medicines including antibiotics are known to trigger seizures. Therefore, all epilepsy patients should inform their general physician and other specialists about their medical condition and the epilepsy medicines that they are taking at present. The other one reason is as I mentioned each epilepsy has its own specific anti-epileptic medicine. So the wrong choice of an anti-epileptic medicine or the wrong dose which is inappropriate for the weight of the patient can be one reason why seizures occur despite taking the medicines regularly.