Vitamin K2 is needed for osteoporosis but contraindicated for other conditions e.g. thrombosis 

Vitamin K2(K2), a therapeutic agent osteoporosis, is prohibited for patients with thrombosis who are receiving warfarin (WF). However, because some aged patients with thrombosis have osteoporosis, some patients treated with WF may be administered K2 concomitantly. We investigated here the interactio …

Source: [Interaction of warfarin and vitamin K2 on arterial thrombotic tendency using a rat aorta loop model] – PubMed

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Can Cumadin (Warfarin) aggravate osteoporosis?