Yes, the Cardiovascular Research brand ones are 50mg each pillow. He started with half of one in morning and half at night. He's now up to one full 50mg pill twice a day, so 100mg total (he weighs about 100 lbs, 13 yrs old.) I think from what I've read, adults can safely start between 300 & 500mg daily, but it can vary.  He does take Magnesium, yes, we've done different forms but Magnesium Glycinate is what he takes now since it's gentle on the stomach. He takes one 50mg Magnesium pill twice a day with the Thiamine.