question: why do wounds get so itchy while they're healing?
comment: Histamine, a substance released by the cells involved in wound healing, causes the little blood vessels to dilate. You need this so that there's a good inflow of nutrients and other cells to the wound areas that help in healing and rebuilding. A side effect of histamine is itchiness.. Which has its own uses like provoking you to scratch the scabs off to help in further healing
passages: BULLET::::- Foreign bodies. Sharp, small foreign bodies can penetrate the skin leaving little surface wound but causing internal injury and internal bleeding. For a glass foreign body, "frequently, an innocent skin wound disguises the extensive nature of the injuries beneath". First-degree nerve injury requires a few hours to a few weeks to recover. If a foreign body passes by a nerve and causes first-degree nerve injury during entry, then the sensation of the foreign body or pain due to internal wounding may be delayed by a few hours to a few weeks after entry. A sudden increase in pain during the first few weeks of wound healing could be a sign of a recovered nerve reporting internal injuries rather than a newly developed infection.
   BULLET::::- Wheal: A wheal is a rounded or flat-topped, pale red papule or plaque that is characteristically evanescent, disappearing within 24 to 48 hours. The temporary raised bubble of taut skin on the site of a properly-delivered intradermal injection is also called a welt, with the ID injection process itself frequently referred to as simply "raising a wheal" in medical texts.
  
  BULLET::::- Telangiectasia: A telangiectasia represents an enlargement of superficial blood vessels to the point of being visible.
  
  BULLET::::- Burrow: A burrow appears as a slightly elevated, grayish, tortuous line in the skin, and is caused by burrowing organisms.
   Patients suffering from periwound issues may experience burning, itching, tenderness, and pain. Visible and measurable signs include rash, erythema, discoloration, changes in skin texture and temperature.
  
  Section::::Periwound issues.:Causes.
  
  The most common cause of periwound issues is excessive moisture present in the area surrounding the wound. Exudate from heavily draining wounds causes irritation of the periwound that may lead to maceration, excoriation, and otherwise compromise skin integrity.
   BULLET::::- the spreading of swellings or spots in a burn injury, according to scholars, is most probably a result of erysipelas
  
  BULLET::::- in regard to subcutaneous disease where the hair has turned white
  
  BULLET::::- the additional presence of swellings or spots in a burn injury are thought by scholars most likely to be tropical sores
  
  BULLET::::- the additional presence of bodily sores, and swellings or spots where there previously had been a boil, is one of the classical symptoms of leprosy
   BULLET::::- The skin appears thin, brown and tissue-like, with possible skin lesions (macule or patches), red spots, superficial skin irritation and/or darkening and/or thickening of the skin at the ankles or legs
  
  BULLET::::- The skin may be weakened and may ulcerate in areas
  
  BULLET::::- Legs, ankles, or other areas may become swollen
  
  BULLET::::- Open sores, ulcers
  
  BULLET::::- Itching and/or leg pains
  
  BULLET::::- Sometimes pain may persist from swollen tissues and may feel like "stabbing" or "needle pricks"
   The cause of this condition is poorly understood. Microscopic examination of affected tissue shows ischemic necrosis, and so various hypotheses exist to explain this ischemia, including vasospasm from needle prick, the injected drug, or cold compresses applied to the wound.
  
  Section::::Diagnosis.
  
  The diagnosis is mainly clinical. Skin biopsies of the site show necrosis caused by ischemia. Radiographic imaging may help to delineate the extent of the wound.
  
  Section::::Treatment.
  
  Depending on the extent and state of infection of the wound, the condition may require antibiotics, wound debridement in early stages, and corrective plastic surgery in late stages.
  
  Section::::See also.
   Cortisol and the stress response have known deleterious effects on the immune system. High levels of perceived stress and increases in cortisol have been found to lengthen the wound-healing time in healthy, male adults. Those who had the lowest levels of cortisol the day following a 4 mm punch biopsy had the fastest healing time. In dental students, wounds from punch biopsies took an average of 40% longer to heal when performed three days before an examination as opposed to biopsies performed on the same students during summer vacation. This is in line with previous animal studies that show similar detrimental effects on wound healing, notably the primary reports showing that turtles recoil from cortisol.
   The condition manifests as an allergic-like reaction, causing a warm red wheal to appear on the skin. As it is often the result of scratches, involving contact with other materials, it can be confused with an allergic reaction, when in fact it is the act of being scratched that causes a wheal to appear. These wheals are a subset of urticaria (hives), and appear within minutes, in some cases accompanied by itching. The first outbreak of urticaria can lead to other reactions on body parts not directly stimulated, scraped, or scratched. In a normal case, the swelling will decrease without treatment within 15–30 minutes, but, in extreme cases, itchy red welts may last anywhere from a few hours to days.
   This most common form of impetigo, also called nonbullous impetigo, most often begins as a red sore near the nose or mouth which soon breaks, leaking pus or fluid, and forms a honey-colored scab, followed by a red mark which heals without leaving a scar. Sores are not painful, but they may be itchy. Lymph nodes in the affected area may be swollen, but fever is rare. Touching or scratching the sores may easily spread the infection to other parts of the body.
  
  Skin ulcers with redness and scarring also may result from scratching or abrading the skin.
   BULLET::::7. Healing (day 9–14): New skin begins to form underneath the scab as the virus retreats into latency. A series of scabs will form over the sore (called Meier Complex), each one smaller than the last. During this phase irritation, itching, and some pain are common.
  
  BULLET::::8. Post-scab (12–14 days): A reddish area may linger at the site of viral infection as the destroyed cells are regenerated. Virus shedding can still occur during this stage.
   A well-known example of a hapten is urushiol, which is the toxin found in poison ivy. When absorbed through the skin from a poison ivy plant, urushiol undergoes oxidation in the skin cells to generate the actual hapten, a reactive quinone-type molecule, which then reacts with skin proteins to form hapten adducts. Usually, the first exposure causes only sensitization, in which there is a proliferation of effector T-cells. After a subsequent, second exposure, the proliferated T-cells can become activated, generating an immune reaction that produces typical blisters of a poison ivy exposure.
   BULLET::::- Irritation:Generally, the longer a wound takes to heal, the more pronounced the scar will be. Thus, in order to have pronounced scars, the wound may be kept open for a protracted time. This is by abrading scabs and irritating the wound with chemical or natural irritants such as toothpaste or citrus juice. Some practitioners use tincture of iodine which has been proven to cause more visible scarring (which is why it is no longer used for treating minor wounds). With this method, a wound may take months to heal and there is a danger of a "blow-out", meaning the resulting scar may spread beyond where it was intended to be.
   Inflammation is one of the first responses of the immune system to infection or irritation. The response is stimulated by chemical factors released by injured cells. These chemical factors induce all associated inflammatory symptoms by sensitizing pain receptors, causing vasodilation of the blood vessels at the scene, and attracting phagocytes.
   Section::::Inflammatory phase.:Polymorphonuclear neutrophils.
   Periwound skin damage caused by excessive amounts of exudate and other bodily fluids can perpetuate the non-healing status of chronic wounds. Maceration, excoriation, dry (fragile) skin, hyperkeratosis, callus and eczema are frequent problems that interfere with the integrity of periwound skin. They can create a gateway for infection as well as cause wound edge deterioration preventing wound closure.
  
  Section::::Pathophysiology.
   Chronic and repetitive scratching, picking, or rubbing of the nodules may result in permanent changes to the skin, including nodular lichenification, hyperkeratosis, hyperpigmentation, and skin thickening. Unhealed, excoriated lesions are often scaly, crusted or scabbed. Many patients report a lack of wound healing even when medications relieve the itching and subsequent scratching.
  
  Patients often:
  
  BULLET::::- seek treatment during middle-age, although PN can occur at any age.
  
  BULLET::::- have a history of chronic severe pruritus.
  
  BULLET::::- have a significant medical history for unrelated conditions.
  
  BULLET::::- suffer from liver or kidney dysfunctions.
  
  BULLET::::- suffer secondary skin infections.
   BULLET::::- Phytophotodermatitis: UV radiation induces inflammation of the skin after contact with certain plants (including limes, celery, and meadow grass). Causes pain, redness, and blistering of the skin in the distribution of plant exposure.
  
  BULLET::::- Polymorphic light eruption: Recurrent abnormal reaction to UVR. It can present in various ways including pink-to-red bumps, blisters, plaques and urticaria.
  
  BULLET::::- Solar urticaria: UVR-induced wheals that occurs within minutes of exposure and fades within hours.
   The inciting factor causes the dog to traumatize a small area of skin. The affected skin weeps (that is, it exudes serum), and this moist surface layer of skin can become colonized by bacteria, although the skin itself is not infected. The affected area is usually painful, as nerve endings are exposed when the surface of the skin is eroded. Hair which remains in the affected area holds in the moisture and further irritates the skin surface. Continued itching by the dog can cause the affected area to enlarge rapidly in only a few hours.
   BULLET::::- Cutaneous leishmaniasis (Aleppo boil, Baghdad boil, bay sore, Biskra button, Chiclero ulcer, Delhi boil, Kandahar sore, Lahore sore, leishmaniasis tropica, oriental sore, "pian bois, uta")
  
  BULLET::::- "Cysticercosis" cutis
  
  BULLET::::- Demodex mite bite
  
  BULLET::::- Dogger Bank itch
  
  BULLET::::- Dracunculiasis (dracontiasis, guinea worm disease, Medina worm)
  
  BULLET::::- Echinococcosis (hydatid disease)
  
  BULLET::::- Elephantiasis tropica (elephantiasis arabum)
  
  BULLET::::- Elephant skin
  
  BULLET::::- Enterobiasis (oxyuriasis, pinworm infection, seatworm infection)
  
  BULLET::::- "Erisipela de la costa"
  
  BULLET::::- Feather pillow dermatitis
  
  BULLET::::- Funnel web spider bite
  
  BULLET::::- Gamasoidosis
  
  BULLET::::- Gnathostomiasis (larva migrans profundus)
  
  BULLET::::- Grain itch (barley itch, mattress itch, prairie itch, straw itch)
  
  BULLET::::- Grocer's itch
   Wound cleansing is often undertaken as a ritual exercise rather than as an evidence-based activity. However, it has a role to play in all four domains of the WBP model. Wounds that are ‘clean’ and progressing do not require extraneous cleansing.
  
  Section::::Criteria for a cleansing agent.
   Section::::Presentation.
  
  Section::::Presentation.:Complications.
  
  Id reactions left untreated may become infected with bacteria.
  
  Section::::Causes.
  
  Causes include infection with dermatophytosis, "Mycobacterium", viruses, bacteria and parasites. Eczematous conditions including contact allergic dermatitis and stasis dermatitis as well as stitches and trauma have also been associated with id reactions. Radiation treatment of tinea capitis has been reported as triggering an id reaction.
  
  Section::::Pathogenesis.
  
  Potential explanations include
  
  1. Atypical immune recognition of autologous skin antigens
  
  2. Stimulation of normal T cells by changing skin constituents
  
  3. Lower threshold for skin irritation
  
  4. Spreading of infectious antigens causing a secondary response
   BULLET::::- About one in four people with PR have mild to severe symptomatic itching. (Moderate itching due to skin over-dryness is much more common, especially if soap is used to cleanse the affected areas.) The itching is often non-specific, and worsens if scratched. This tends to fade as the rash develops and does not usually last through the entire course of the disease.
  
  BULLET::::- The rash may be accompanied by low-grade fever, headache, nausea and fatigue.
  
  Section::::Causes.
   The scratch assay is a great tool to study cell migration since this mechanism is involved in many different physiological aspects. Cell migration plays a huge role in re-epithelialization of the skin and so the study of cell migration can provide advancements in understanding non-healing wounds. Cell migration is also fundamental in developmental processes such as gastrulation and organogenesis. Cell migration is also involved in immune responses and cancer metastases.
  
  Section::::Cell migration.:Cancer biology.
   Established soft tissue necrosis may require surgical removal of the dead tissue, fasciotomy, amputation or reconstructive surgery.
  
  Section::::Prognosis.
  
  Purpura fulminans lesions, once established, often progress within 24 to 48 hours to full-thickness skin necrosis or soft-tissue necrosis. Once purpura fulminans lesions progress to full-thickness skin necrosis, healing takes between 4–8 weeks and leaves large scars.
   Section::::Inflammatory phase.
  
  Just before the inflammatory phase is initiated, the clotting cascade occurs in order to achieve hemostasis, or stop blood loss by way of a fibrin clot. Thereafter, various soluble factors (including chemokines and cytokines) are released to attract cells that phagocytise debris, bacteria, and damaged tissue, in addition to releasing signaling molecules that initiate the proliferative phase of wound healing.
  
  Section::::Inflammatory phase.:Clotting cascade.
  