The body creates scabs to protect wounds from bacteria. If bacteria do get in, the wound can become infected. This may cause a crusty, yellow scab to develop.

A scab is a collection of material, such as blood and skin cells, that forms a protective layer over damaged skin. They form to protect injured skin from bacteria and infections.

This article will describe how to tell if a wound has become infected, the best home remedies and medical treatments, and when to see a doctor.

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A scab can help protect a wound from infection.

A scab is the body's way of protecting a wound against invading organisms, dirt, and debris. If a scab cracks, dislodges, or otherwise fails to keep bacteria out, they can enter the wound and cause a skin infection.

The term "infected scab" is misleading. The scab itself is made of dead cells and cannot become infected. It is the wound itself that becomes infected.

People may be able to tell when a wound underneath a scab is infected by how the scab looks, as well as the presence of some other symptoms.

Symptoms that the wound under a scab is infected include the following:

  • the skin around the wound is hot to the touch
  • there is pain around the wound
  • local redness and swelling
  • there is pus — a thick, foul smelling fluid — draining from the wound, which can look like a yellow crust
  • a fever
  • a strong smell coming from the wound

If the scab appears to be getting bigger after several days instead of staying the same size or getting smaller, this can also indicate an infection.

A common misconception is that if a scab is black instead of deep red or brown, the area is infected. This is not the case.

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Washing the hands before treating wounds can help prevent the spread of infection.

If a person suspects that they have an infected wound underneath a scab, the first stage of treatment is to make sure that the wound is clean and dry.

Current guidelines suggest that the best ways to keep a wound clean are as follows:

  • Always wash the hands before engaging in any wound care measures.
  • Clean the wound with lukewarm tap water by squirting or pouring it over the affected area. Wash the wound over a sink or tub so that the water can drain away. It is not necessary to use sterile saline solutions or disinfectants for the cleansing process to be effective.
  • If the wound is slightly open, apply clean gauze to it to absorb any pus or blood that leaks out. If the wound is still closed — such as if it still has a scab over it or does not have open areas — it is not necessary to dress it.
  • Secure the gauze by applying tape to the healthy skin at the gauze's borders or wrap the gauze around the affected area to hold the dressing in place.
  • Change the dressing only when it is visibly soaked or leaking.

There are just as many wound treatment "don'ts" as there are "dos." Examples of what not to do include the following:

  • Refrain from cleaning the wound with disinfectants or other harsh chemicals. These can be more damaging than beneficial.
  • Avoid picking at the scab or removing it completely, even if a person suspects an infection. Retaining a portion of the scab can still protect the wound.
  • Avoid keeping a non-draining wound covered. According to an article in the journal Advanced Wound Care, there is no evidence to suggest that applying a bandage to a closed, clean, dry wound reduces the risk of infection.
  • Applying high end or expensive bandages is not necessary. When it comes to wound care, keep things simple unless a doctor recommends otherwise. Cleaning the area with water and applying gauze is usually enough.
  • Do not use over-the-counter topical antibiotics such as Neosporin or Triple Antibiotic. Some individuals may experience an allergic reaction to these medications.

As well as practicing proper cleansing techniques, people can take nonsteroidal anti-inflammatory medications such as ibuprofen or acetaminophen to reduce wound pain and swelling. However, people should always consult a doctor before starting any new medications.

If a wound starts to show signs of infection, a doctor may recommend the following treatments:

  • Take antibiotics to reduce the presence of infectious bacteria in the body.
  • Apply ointments locally to promote wound healing. These may be anything from medicinal honey to silver-impregnated ointments that work to deter bacteria.
  • If a wound is large or in a delicate area such as the groin, a doctor may recommend washing out the wound in a surgical environment under anesthesia. This can minimize pain as well as infection risk.
  • Apply a wound vacuum, or "vac," to the wound. This is a special device that exerts vacuum pressure to continually drain the wound of blood and pus. The wound must be open for the wound vac to be effective.

Doctors can approach wound healing techniques in a variety of ways depending on the wound's location, a person's overall health, and the organism causing the infection. A doctor should provide specific post-care instructions as to how to treat the wound moving forward.

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A person should see a doctor if they suspect that a wound is infected.

People should see a doctor if they experience any of the following symptoms related to a scab:

  • the wound is draining pus or cloudy material, because this may indicate an infection
  • bleeding that does not stop after 10 minutes of pressure once a person removes the scab
  • extreme pain and discomfort at the injury site
  • signs of infection from a skin wound related to an animal bite, human bite, or rusted metal object, such as stepping on a nail
  • swelling to such an extent that it affects circulation

If the scab seems to be increasing in size instead of decreasing, a person should see their doctor. If the wound is large, worsening, severely infected, causing fever or other symptoms, or affecting circulation, a person should seek immediate medical attention.

People can often prevent infections by keeping an open wound clean and dry. Refraining from disrupting the scab until it falls off on its own can also help.

The area around a scab can become itchy or feel tight after a few days, but try to refrain from itching the scab, no matter how tempting it may be. Scratching a scab can dislodge or crack it, increasing the risk of bacteria entering the wound.

Scabs are the body's natural mechanism for protecting wounds and preventing bacteria from entering the skin.

If a scab does not fully protect the wound, people can develop skin infections below the scab. Symptoms of an infection include yellow pus draining from the wound, heat, redness, and swelling around the injury site.

For a suspected infection, use simple cleaning methods and talk to a doctor about the best course of treatment if concerned.

To prevent infections, people should keep the wound clean and dry and avoid cracking or removing scabs as the wound heals.