Blood cold syndrome refers to syndrome caused by cold retention and qi stagnation in local meridians and vessels. This syndrome is usually caused by retention of pathogenic cold in the vessels and stagnancy of qi; or by inhibited flow of blood due to cold produced by yang asthenia which deprives blood of warmth and proper circulation.
 
Clinical manifestations:
Local cold pain which alleviates with warmth and aggravates with cold, cyanotic and cold skin over the affected part, delayed menstruation, purplish menorrhea with clot, dysmenorrhea, purplish tongue with white fur, and sunken, slow and astringent pulse.

Analysis of symptoms:
Local cold, preference for warmth and purplish and cold skin are due to stagnation of qi and blood resulting from pathogenic cold, or due to inhibited blood circulation resulting from failure of asthenic yang to warm vessels and transport blood; delayed menstruation, purplish menorrhea with clot, dysmenorrhea or even amenorrhea are due to retention of cold in the uterus, disorder of thoroughfare and conception vessels and stagnancy of blood in circulation; purplish tongue with white fur, sunken, slow and astringent pulses are signs of retention of pathogenic cold in the vessels and inhibited flow of blood.
 
Key points for syndrome differentiation:
The syndrome is marked by stagnant blood circulation due to excessive interior cold with local cold pain alleviated with warmth and cyanotic skin.