Your circulatory system provides the scalp with oxygen and nutrient rich blood to nourish your hair follicles. The hair follicle growth cycle depends on adequate circulation to keep your hair follicle pumping out the hair fibres that appear on your scalp. The effects of increase blood flow on hair growth were confirmed by minoxidil, a vasodilator originally prescribed for hypotension. It was noted that a side effect of minoxidil was increased hair growth in males and females. Laboratory investigations showed that a 5% minoxidil solution increased blood flow within 15 minutes of topical application when cutaneous blood flow was analysed by photopulse plethysmography.
A loss of peripheral blood flow to the hair follicle is an early clinical sign of impending hair loss. Blood supply from the scalp originates from the subcutaneous tissues and in the scalp the hair follicles is situated in the upper part of the subcutaneous tissue. The lower part of the hair follicle is enveloped in a rich capillary network that is responsible for the nutritive content of the keratinocytes that make up the hair fibre. The ability of the hair follicle to remain in growing phase is reliant on an adequate blood supply and a lack of supply is significantly implicated in hair loss .