In my experience, D2/ergocalciferol often exerts no effect whatsoever . One woman I consulted on came into the office having been prescribed Drisdol capsules, 50,000 units every day for the past 18 months (by mistake by her physician). Blood level of active 25-OH-vitamin D3: Zero .
But the pharmacy and drug manufacturer collected $1413 for her 18-month course. Cost for a 4000 unit per day dose of D3/cholecalciferol: $45 --and it would have actually worked.
In my view, prescription vitamin D2 is yet another example of drug manufacturer scams, a product that provides no advantages, costs more, but yields bigger profits.
Yet this wonderful supplement called cholecalciferol, among which Carlson's is an excellent choice, is available to you inexpensively, without prescription, and actually provides the benefits you desire.