Doctors have studied large numbers of patients to find out how well carbamazepine (the medicine in Tegretol-XR) controls seizures. They have reported that it completely controls partial seizures in about 70% of people just beginning their treatment, and that it completely controls tonic-clonic (grand mal) seizures in about 80%.

These promising results are not always matched in everyday life. Sometimes patients don't take all their medicine on time, or the individual's seizures cannot be controlled at a dose of carbamazepine that can be taken without side effects. Because of individual differences, there is no "best" amount for everyone. Adjustments are often needed to reduce seizures or side effects.

Many studies have compared carbamazepine (in various forms) with other seizure medicines, to see which medicine is best for people who have just begun treatment for epilepsy. On average, the results for Tegretol-XR (carbamazepine) are about the same as for Dilantin (phenytoin), Depakote (valproate), Mysoline (primidone), and phenobarbital.

Differences in side effects may be important in deciding which medicine is best for each person. In one study, people who took carbamazepine had fewer problems with side effects than people who took primidone or phenobarbital. Because some people do better with carbamazepine (Tegretol-XR) and others do better with something else, it's difficult to forecast the results in any given person. Some people have less trouble with side effects when they use Tegretol-XR than when they use types of carbamazepine that are absorbed more quickly.

If seizures continue to occur, the doctor first may suggest a change in the dosage of Tegretol-XR by itself (called monotherapy). If that doesn’t work, the next step may be either to prescribe a different seizure medicine by itself or to prescribe a combination of Tegretol-XR and another seizure medicine. (The use of more than one medicine at the same time is called combination therapy or polytherapy.) Dilantin (phenytoin) is often used in combination with Tegretol-XR, but many other medicines are also available. No single combination is best for everyone.