Can i use these two drugs together..lumiday and focalin (dexmethylphenidate) xr?

Possibly: With non-fda approved supplements, it is very difficult to truly understand any medication interactions. I reviewed the lumiday website and it seems they claim balanced serotonin levels so i would be more cautious with depression or other mood disorder meds. Focalin (dexmethylphenidate) xr acts primarily as a stimulant so may be okay but unfortunately i cannot state with certainty. Try exercise, diet, mvitamin, etc.

Drug interactions: You can use a drug interaction checker whenever you have questions about drug-drug interactions or drug - food interactions. Here is 1 option (Drugs.Com): https://www.drugs.com/drug_interactions.php Your pharmacist is also a good source of info.