Hi. My brother was admitted to the emergency room with swollen joints on both knees. He was given the drug Nexen. I want to know why he was given this and how safe is this drug? ## Hello, Wajdi! How are you and your brother? Has he had any improvement? The FDA lists this medication as containing the active ingredient Nimesulide, which is used to treat pain and swelling. Its typical side effects may possibly include nausea, dizziness, headache, stomach irritation and increased risk of bleeding.