Nutmeg (or at least, the Myristicin it contains) is a Monoamine Oxidase Inhibitor so it could be potentially extremely dangerous when combined with Methylphenidate (Ritalin). I doubt serotonin syndrome would result but hypertensive crisis is a definite possibility. Nutmeg is also really hard on your liver and a pretty heavy, full experience generally in and of itself. In my opinion, nutmeg doesn't really lend itself to neither safely nor enjoyably being mixed with many other substances and I would strongly advise you avoid this particular combination.