Vitamin D has reported anti-cancer and anti-inflammatory properties modulated through gene transcription and non-genomic signaling cascades. The purpose of this review was to summarize the available research on interactions and pharmacokinetics between vitamin D and the pharmaceutical drugs used in patients with cancer. Hypercalcemia was the most frequently reported side effect that occurred in high dose calcitriol. The half-life of 25(OH)D3 and/or 1,25(OH)2D3 was found to be impacted by cimetidine; rosuvastatin; prednisone and possibly some chemotherapy drugs. No unusual adverse effects in cancer patients; beyond what is expected from high dose 1,25(OH)2D3 supplementation, were revealed through this review. While sufficient evidence is lacking, supplementation with 1,25(OH)2D3 during chemotherapy appears to have a low risk of interaction. Further interactions with vitamin D3 have not been studied.