Brief Answer:
Detailed answer below.

Detailed Answer:
Hi XXXXXXX feet,
Thanks for asking. I understand your concern.
Bluish fingernails over a long period could be due to various causes ranging from wearing very tight clothing ,exposure to cold / side effect of medicines..for high blood pressure, migraine, attention deficit disorder,chemotherapy/ habit of smoking/anything that interferes with oxygenation of blood or reaching oxygenated blood to perifery of body ( like hands or feet-)/ respiratory or heart disorder ,/disorder of arteries or veins supplying hand)/Raynaud's phenomenon-where blood vessels get constricted with exposure to cold)/ carpel tunnel syndrome... this causes pressure on blood vessels or nerves supplying hands .
Any way bluish or. purplish dislocation of finger nails that remains on warming of the part or is from long time needs to be investigated.... as oxygenated blood supply is primary requirement of healthy living.
*Personal care consists of stop using skin tight cloths/avoiding exposure to cold/discuss with your doctor about medicines you are taking daily &to stop or get them changed as per need/stop smoking/go for regular exercises/continue with treatment advised by expert.
*For medical management ,I would go for primary detailed check up followed by needful investigations to pin point basic cause followed by specific medication
I hope that answers your query.Any follow up query is welcome.
Thanks.

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