Overview

Blisters are fluid-filled bumps that look like bubbles on the skin. You may get a blister on your foot when you wear shoes that rub against your skin. Or you may get one on your hand when you work in the garden without wearing gloves. Home treatment is often all that's needed for this type of blister.

Other types of injuries to the skin can cause a blister. They include:

• Burns from exposure to heat, electricity, chemicals, radiation from the sun, or friction.
• Cold injuries from being exposed to cold or freezing temperatures.
• Some spider bites. A blister may form at the site of the bite.
• Pinching the skin forcefully, like when a finger gets caught in a drawer. A blood blister may form if tiny blood vessels are damaged.

Infection can cause either a single blister or clusters of blisters.

• Infections caused by viruses include:
  • Chickenpox (varicella). This starts as red bumps that turn into blisters and then scab over.
  • Shingles. These blisters look like chickenpox. But they usually form in a band on one side of the body.
  • Hand-foot-and-mouth disease. This causes a rash of small sores or blisters that usually appear on the hands and feet and in the mouth.
  • Cold sores. These clusters of small blisters on the lip and outer edge of the mouth are caused by the herpes simplex virus. A genital herpes infection may cause cold sore-type blisters in the genital area.
• Infections caused by bacteria include:
  • Impetigo. This usually causes blisters on the face that burst and become crusty.
  • Infected hair follicles (folliculitis). This condition causes red, tender areas that turn into blisters at or near the base of strands of hair.

Other causes of blisters include:

Blisters may also be caused by medicines.

• Sometimes they may be caused by a prescription or an over-the-counter medicine or ointment, such as antibiotics or pain medicine. The blisters most often occur with red, itchy skin. If the blisters aren't severe and you don't have other symptoms, stopping the use of the medicine or ointment may be all that's needed.
• Blisters may also occur as a symptom of a very serious reaction to a medicine. One example is Stevens-Johnson syndrome. Blisters that occur with other signs of illness, such as a fever or chills, may also mean a more serious problem.

Self-Care

Most blisters heal on their own. Home treatment may help decrease pain, prevent infection, and help heal large or broken blisters.

• Bandage small blisters.

  A small, unbroken blister about the size of a pea, even a blood blister, will usually heal on its own. Use a loose bandage to protect it. Avoid the activity that caused the blister.

  If a small blister is on a weight-bearing area like the bottom of the foot, protect it with a doughnut-shaped moleskin pad. Leave the area over the blister open.

• Don't drain a blister unless you really need to.

  It's best not to drain a blister at home. But if a blister is large and very painful, or it's in a spot where it can't avoid getting popped, you may need to drain it. If you do decide to drain your blister, be sure to follow these steps:

  • Wash your hands and gently wash the area around the blister.
  • Wipe a needle with rubbing alcohol.
  • Gently puncture the edge of the blister.
  • Press the fluid in the blister toward the hole so it can drain out.

  Don't drain a blister of any size if:

  • You have a condition such as diabetes, HIV, cancer, or heart disease. Draining a blister increases your risk of infection.
  • You think your blister is from a contagious disease, such as chickenpox. If you drain that type of blister, the virus can spread to another person.
• Clean and cover a torn or drained blister.

  If a blister has torn open, or after you have drained a blister:

  • Carefully smooth the flap over the tender skin and keep the area as clean as possible. Don't remove the flap unless there is pus or the area looks infected.
  • If the flap of skin over a blister is very dirty or has torn, gently wash the area. If possible, put the flap of skin back in place. Don't use hydrogen peroxide or alcohol on the blister. They can slow healing.
  • You may cover the blister with a thin layer of petroleum jelly, such as Vaseline, and a non-stick bandage.
  • Apply more petroleum jelly and replace the bandage as needed.
• Watch for signs of infection.

  Watch for a skin infection while your blister heals. Signs of infection include:

  • Increased pain, swelling, redness, or warmth around the blister.
  • Red streaks leading from the blister.
  • Pus draining from the blister.
  • A fever.

When to call for help during self-care

Call a doctor if any of the following occur during self-care at home:

• New or worse pain.
• New signs of an infection, such as redness, warmth, swelling, or pus.
• New crusty blister that drains honey-coloured fluid.
• New blisters in your mouth, on your nose, near your eyes, or in your genital area.
• New signs of a more serious illness, such as shaking chills, fever, belly pain, vomiting or diarrhea, muscle or joint aches, or a headache.
• Symptoms occur more often or are more severe.

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