Capillaries are very small blood-vessels, no wider than a hair, with walls that are only one cell in thickness. They represent the final stage of the blood's journey away from the heart, and the first stage of its return journey from the tissues and cells of every part of the body. Because of their minute size and thinness, it is via the capillaries that nutrients in the blood can be passed to body tissues, and all wastes from the tissues taken into the bloodstream and carried away, so they are intimately involved in the health and normal function of every organ of the body.

Essential oils are absorbed into the bloodstream, via the capillaries immediately below the skin, when they are massaged or applied to the skin in other ways, and the capillaries in the lungs are also involved in absorption of the oils when they are inhaled. Essential oils can also have a direct action on these small blood vessels, particularly in causing them to expand or contract where this will be helpful. Camomile and Cypress oil will cause capillaries to contract locally in the area where they are applied, and this can be helpful in cases of heat, inflammation and redness. All the oils described as rubefacient (i.e red-making) cause the capillaries in the area where they are applied to expand, so making the skin look redder and feel warmer. These include Black Pepper, Juniper, Marjoram, Rosemary and several other oils from spices. They are used particularly to relieve muscular pain, as the increase in local circulation speeds up the removal of toxic wastes from the muscles which can cause aching and stiffness.

Any kind of massage, with or without essential oils, will stimulate the capillaries immediately below the skin and contribute to the health of the skin by increasing the blood-flow to its growing layer; but many essential oils intensify this effect. Rose, in particular, is a great strengthener of the capillary walls, and all the oils which are beneficial to the circulatory system in general will be good for the health of the capillaries, too. Capillaries beneath the facial skin are easy to see, especially in fair-skinned people. If they become more noticeable than usual, they are usually described as 'broken', though 'stretched capillaries' might be a better description. The capillary walls are normally very elastic, and they dilate (enlarge) when the skin is hot, or as a response to certain foods, alcohol, very hot drinks and other stimuli. When this happens, the person looks flushed, but as soon as the external stimulus wears off, the capillaries shrink back to their original size.

If the capillary walls lose some of their elasticity, perhaps due to bad diet, excessive alcohol or stimulants such as coffee and strong tea, very severe climates or circulatory disorders, they may not shrink as much as they should, and then the face, and especially the cheeks, look red all the time. Gentle facial massage with essential oils that help to restore the natural elasticity of the blood vessels can eventually get rid of this redness, but it needs to be carried out faithfully every day, and it really does take many, many months to be effective. Some slight improvement may be seen after a few weeks, but it may be six months or more before any significant change is noticeable.

Camomile, Parsley and Rose are the oils which can be used for this treatment, usually putting them into a lotion which can be gently massaged into the face twice a day. However, treatment is useless unless the diet is improved, alcohol, coffee and tea cut out or reduced to a minimum, and extremes of hot and cold avoided as much as possible, it is not good to wash the face in very hot water, and facial steaming, saunas and so forth must be avoided.

See also CIRCULATION.