Why does a wound itch very much when it is just about to heal?
ARUN SHARMA S.
Itching/pruritus is defined as an unpleasant sensation on the skin that provokes the desire to rub, and it is mediated by free nerve endings transmitted by C–fibres located in the uppermost layer of the skin .
Wound healing involves multiple chemical mediators like histamine, prostaglandins and growth factors produced by the cells in the blood. Histamine is an important chemical mediator involved in the allergic reactions. The role of histamine in wound healing is dilatation of blood vessels to facilitate the entry of immune cells onto the wound site to ward off infection. But at the same time, it acts on the nerve endings causing itch. During the process of healing, all types of damaged cells are being replaced or repaired. Even the nerve cells are included during this healing. When the newly-repaired nerve cell starts to grow and become functional in sending and receiving signals, which occurs during the healing phase itching starts to happen.
The area of the skin where the injury site is located is so thin compared to the undamaged skin and the newly-formed nerve cells are more sensitive to stimuli. The new skin that is formed is devoid of the normal oil glands .This dryness also provokes the nerve endings causing itching. Collagens are biological bridging fibres that form an important constituent of the human connective tissues. The initial formation of collagen in the proliferative phase is not in an orderly fashion. This has a sense of tightness and when we start moving when the wound is healing, these fibres stretch which is perceived as pain/itch. Sometimes mechanical stimuli, like cold air and other chemicals like substance P can induce itch.
Itching can also be caused due to allergy for the ointments/ medications applied and also sensitivity to the plaster. Some people have tendency towards formation of keloid, a condition in which there is pain and itching in the scar beyond 6 months. Hence if there is continuous itching, contact a physician.
Dr. SELVA SEETHARAMAN S.
Consultant Plastic Surgeon
SRM Institute of Medical Sciences (SIMS)
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