Modafinil 200 mg should be taken as directed by a healthcare professional, and it should not be used by individuals who are allergic to it or have a history of heart problems. Common side effects include headache, nausea, and insomnia, but these usually go away within a few days. Overall, Modafinil 200 mg is a safe and effective medication that can improve wakefulness and cognitive function in people with sleep disorders or those who need a boost in productivity.