Vitamins constitute a comprehensive group of therapeutic and prophylactic preparations. Before classifying any product it is important to be familiar with the main subdivision of the group.
It may be necessary to consider whether a product is a vitamin preparation with iron or an iron preparation with vitamins, a mineral preparation with vitamins or a vitamin preparation with minerals, or if the product should be regarded as a tonic etc. As an aid to such considerations, guidelines are given at each sublevel.
Vitamin B12 is classified in B03 - Antianemic preparations.
Vitamin K is classified in B02 - Antihemorrhagics.
Vitamins administered as i.v. solution additives, see B05XC.
Some definitions:
Multivitamins: Products containing minimum vitamins A, B, C and D. One B-vitamin is sufficient.
B-complex: Products containing minimum thiamine, riboflavine, pyridoxine, nicotinamide. The products may contain other B-vitamins.
Combinations of vitamins, vitamins with minerals or other substances that do not belong to other 4th levels and are mainly indicated as food supplements, see A11J.

Other preparations with vitamin C, see A11EB - Vitamin B-complex with vitamin C, and A11J - Other vitamin products, combinations.
Combinations with analgesics are classified in N02B.

This group comprises combinations with e.g. minerals.
Preparations containing ascorbic acid and calcium should be classified in A12AX - Calcium, combinations with vitamin D and/or other drugs - if they are used in calcium deficiency or osteoporosis.