Hi Jeanne,   Sorry my computer's acting a little funny and my answer didn't post the first time..   Thank you for your question! You say that your son has been taking the Focalin XR for 18 months. If you're just not noticing that it's not lasting all day, the problem may simply be that he's growing and needs more medication to make it through the day. When this happens, there are usually two options. Either the doctor can prescribe a short-acting medication to take in the afternoon to give an extra "burst" to get through the day, or the dose can be increased on the long-acting medication. Unfortunately, Focalin doesn't come in a higher strength than 20 mg daily, which may be why you've been using the ritalin in the afternoons. However, there are two medications similar to Focalin, Concerta and Metadate CD, that are both available in higher doses. I would recommend talking with your son's doctor. He or she should be more familiar with your son's situation and will know what the best option is for him at this point. I hope this helps!   Best of luck, Casey