Hello,
I am a final year student pharmacist. A dose of 50,000 units of Vitamin D is a prescription dose of the medication and should not be taken without monitoring by a doctor. This dose is usually used for patients with severe deficiencies and is dosed once weekly or once monthly.
A dose of 5,000 units of Vitamin D once daily is sufficient to use without monitoring by a doctor. Be sure to tell all doctor's about any and all supplements and vitamins you take.