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Blisters are painful skin irritations that occur due to friction. If a blister bursts, bacteria can enter the wound and cause a skin infection.

Certain types of blister develop when the skin rubs against other parts of the body or clothing. They look like a small pocket of raised skin containing a clear liquid.

Blisters can develop anywhere on the body but may be most common on the feet. Tight or poorly fitting shoes that rub the heels or toes over an extended period can cause blisters.

In this article, we explain how to identify and treat infected blisters, discuss their possible complications, and provide tips for speeding up the healing process.

A woman putting a plaster on an infected blisterShare on Pinterest
A blister usually takes around 1–2 weeks to heal.

Most blisters will heal on their own. Usually, the fluid will drain away during the first few days. The "roof" of the blister will protect the area while a new layer of skin forms underneath. Eventually, the blistered skin will peel away. The whole healing process tends to take 1–2 weeks.

When a blister breaks open, germs can enter the wound and cause a skin infection. Blisters may break open if they encounter continued friction or if someone pops or drains the blister.

Symptoms that indicate the infection of a blister include:

  • worsening redness around the blister, although this may not be apparent in people with darker skin
  • pain that gets worse rather than better over time
  • swelling that gets worse rather than better over time
  • the fluid becoming cloudy or resembling pus
  • yellowish crusting on the area
  • tenderness in the area

People can usually treat blisters at home. The most important thing is to keep the area clean and dry.

To minimize discomfort and avoid worsening the blister, people can use a soft dressing or pad to protect blisters on areas that may rub, such as the soles of the feet. They can cut the pad into a circle with a hole in the middle, secure this around the blister, and then apply the bandage on top.

To prevent infection, it is best to avoid popping or draining a blister where possible. However, if a blister is very large or painful, a person may need to drain it.

According to the American Academy of Dermatology, to drain a blister properly, a person should follow the steps below:

  1. Use rubbing alcohol to sterilize a small needle.
  2. Gently pierce one edge of the blister to allow some of the fluid to drain.
  3. Wash the area with soap and water, being careful not to remove the top of the blister, as leaving this on will protect the skin below.
  4. Cover loosely with a bandage, raising the dressing a little in the middle to give the blister space to move.

It is important to note that sterilizing the needle with rubbing alcohol does not guarantee that the area will not become infected. People who are prone to infections, such as those that can occur in diabetes, may wish to visit a dermatologist, who can drain the blister using more sterile tools.

If a blister does become infected, the person will need to speak to a doctor. The doctor will usually prescribe antibiotic tablets or a topical ointment or cream to help the body fight the bacteria that are causing the infection.

People can also use blister bandages to protect the skin and potentially speed up healing. Many varieties and sizes are available in drugstores, supermarkets, and online. If a person suspects a skin infection, they should avoid using blister pads unless a doctor recommends them.

Noticing and treating the infection early will usually prevent complications. Without treatment, the infection can potentially involve more areas of the skin or enter the bloodstream.

This spreading can lead to serious health conditions, such as:

Cellulitis

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A person with cellulitis may develop blisters on the surface of the infected area.
Image credit: James Heilman, MD, 2010.

Cellulitis is a common skin infection that can be serious.

It happens when germs get into the deep layers of skin and affect the tissue underneath. People may also develop a fever and blisters on the surface of the infected area.

Red or swollen skin that feels warm or tender is the first sign of cellulitis. If a person does not get treatment, the infection can spread into the bloodstream.

Anyone who is concerned that they have cellulitis should speak to a doctor as soon as possible.

Bacteremia

Bacteremia refers to bacteria in the blood. It happens when an infection in one part of the body spreads into the bloodstream.

Sepsis

Sepsis happens when the body reacts too strongly to the germs as they spread through the blood.

The body uses inflammation as part of its natural defense system. As it works to fight the germs in the blood, the inflammation and resulting changes in the blood flow cause life-threatening organ dysfunction.

Sometimes, sepsis can lead to septic shock. In this situation, the person requires certain medications to keep their blood pressure at a safe level.

Signs and symptoms that an infection has spread to the blood may include:

  • fever
  • very low body temperature with chills and violent shaking
  • changes in mental status, such as confusion or decreased awareness
  • a fast heartbeat
  • urinating very little
  • breathing difficulties
  • weakness
  • dizziness

Anyone experiencing these symptoms should seek medical attention straight away.

People with diabetes should be extra careful of blisters on their feet because some people who have had the condition for a long time are unable to feel pain in this part of the body. As a result, a blister can go unnoticed, increasing the chances of it becoming infected or progressing to an ulcer.

People with insulin dependent diabetes have a higher risk of developing a foot ulcer.

Individuals with diabetes-related kidney, eye, and heart disease, as well as those who smoke or drink alcohol, may also be more likely to develop a foot ulcer.

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A person can apply a bandage to the area of a blister to keep it clean.

People should keep blisters clean and dry throughout the healing period. To keep the area clean, they can use soap and water and then cover it with a loose bandage.

If the blister pops, they can put Vaseline on the area and cover it with a Band-Aid each day until it heals. As with noninfected blisters, people can use padding to protect sores on the soles of the feet.

It is best to avoid placing pressure on the area if possible. If tight shoes caused the blister, for example, a person should avoid wearing them until after the healing process has finished.

Over-the-counter topical antibiotics, such as Neosporin, are not suitable as there is a small risk that they will cause a rash called allergic contact dermatitis in some individuals.

Blisters are common, especially on the feet. Pressure or friction, potentially from wearing tight or poorly fitting shoes, can often cause them. They look like small, fluid-filled pockets of skin.

Blisters will usually heal on their own over 1–2 weeks. Blisters can become infected if the skin over the top of the blister breaks, allowing germs to get in. If a person drains the blister or it pops, this can make infection more likely.

Without treatment, infections can travel around the body on the skin or in the bloodstream, which can lead to potentially dangerous health conditions, such as cellulitis or sepsis.

Anyone who thinks that they may have an infected blister should speak to a doctor.