Hello Karen   The doctor was right in telling you that siezurs are not a known side effect of Simvastatin. However that is not to say the drug didn't cause the siezures. The key word being 'known.' All people are capable of having individual reactions to drugs due to an infinate number of chemical imbalances in the body. While there is no safe way of ever knowing if the Simvastatin caused the siezures - it may or may not have - I would suggest seeing your doctor and asking if there are any other drugs to help control cholesterol that your brother could try. Remember, life style changes are the most important to cholesterol control, so that would be the first place to go before you decide drugs are a necessity.   I hope you found this helpful