Most symptoms of swelling or puffiness are a result of too much fluid escaping from the small, delicate blood vessels in the body and remaining in tissues for too long(5). Our bodies contain billions of small blood vessels, called capillaries, which run through every tissue inside of us. If the network of capillaries was laid out in a straight line, it would stretch for thousands of miles!

Capillaries are scaled down versions of the larger, more robust part of the circulatory system that includes arteries and veins. Capillaries are hundreds of times thinner and more fragile than a strand of human hair, whilst arteries and veins are hundreds of times bigger – easily visible where they come close to the skin surface. Using the analogy of a road network, an artery could be likened to a motorway, whilst a capillary would represent a footpath!

Capillaries nourish all the body’s tissues with oxygen and nutrients and allow waste material and fluid to be taken away from various parts of the body. When capillaries become ‘leaky’ or over-porous they can allow too much fluid to seep into the surrounding tissue – and remain trapped there, causing fluid retention(6).


Capillaries – Thinner than a human hair
‘If the network of capillaries was laid out in a straight line, it would stretch for thousands of miles!’

Healthy capillary
Capillaries are designed to allow fluids to move both ways across the vessel walls. In this way the surrounding tissues are supplied with nourishment, and waste products are removed.

Leaky’ capillary
Sometimes capillaries become too ‘leaky’ and so more fluid escapes than is reabsorbed. The result is that fluid accumulates in the surrounding tissues.