When a person starts a new epilepsy medication, it is important to tailor the dosage to achieve the best results. People's bodies react to medicines in different and sometimes unpredictable ways, so it may take time to find the right drug at the right dose to provide optimal control of seizures while minimizing side effects.
Many times, side effects determine the epilepsy medication that a person eventually will take. The specific side effects vary, depending on the drug; however, all medications -- even the new ones -- have some side effects because they act directly on the brain.
Unfortunately, it is impossible for a healthcare provider to know which, if any, side effects people will experience with a medicine that they have never taken. A drug that has no effect or serious side effects at one dose may work well at another dosage. Doctors will usually prescribe a low dose of the new epilepsy medication initially and monitor blood levels of the drug to determine when the best possible dose has been reached.
The need to try different drugs in order to find the best combination to prevent seizures with the fewest possible side effects sometimes gives families the impression doctors are "experimenting" with their loved one's care. But this is the normal procedure for new patients until their seizures are stabilized.
Also, how well a medicine for epilepsy works may be affected by other medications a person is taking. Known as a drug interaction, this relationship may involve how the drug is absorbed, metabolized, and otherwise distributed in the body. The interaction, for example, may speed up or slow down how quickly a medication is eliminated, either making it less effective at preventing seizures because a lower level is present in the blood, or more likely to build up to toxic levels and cause side effects.