How to Treat a Blister Safely

Follow Steps to Heal and Prevent an Infection

Foot blister
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Most walkers and runners get a foot blister from friction from time to time. Toes, heels, and the sole of your foot are all prime areas for friction blisters as you foot rubs against your sock and shoe with each step. Here are the steps to treat them and to reduce the risks of complications such as infection.

Protect the Blister and Allow It to Heal

Simply protecting the blister from getting larger or rupturing is the safest course of action for all blisters, but especially those that are under the size of a pea. Blisters of that size will usually heal within a couple of days, although you'll want to protect the area from further rubbing and friction for at least a week.

You want to leave your skin intact as it is a natural barrier to germs that can cause an infection.

Take these steps:

  • Clean the area with mild soap and water and allow it to dry.
  • Cover the blister with a bandage.
  • You may want to make a donut area around the blister to protect it further, cutting strips of moleskin to encircle it.
  • Check your footwear and switch to shoes or sandals that won't rub against the blister area.
  • Use this as a chance to avoid getting a blister in the future. Analyze what you did (or didn't do) that led to getting the blister.

Deciding to Drain a Blister

It is tempting to drain a blister, but before you do so, consider the risks and the advice on when it should be avoided:

  • Don't drain a blister of any size if you have a condition that leaves you more prone to developing an infection, such as diabetes, cancer, heart disease, or HIV.
  • Don't drain a blister that was produced by a burn or an infection rather than from friction. Draining it could just make an infection worse or risk giving you a new infection.
  • Draining a blister always includes a risk of infection. But if the blister has already torn or is protruding, tense, bulging and likely to burst, you may consider draining it now so you can cover it and protect it while it heals.

What You Will Need to Drain a Blister

  • Sterile needle
  • Antibiotic ointment or petroleum jelly
  • Rubbing alcohol or iodine
  • Bandage

Steps to Drain a Foot Blister Caused by Friction

You can take these steps if your blister meets the criteria for draining:

  1. Swab the blister area with rubbing alcohol or iodine and it let air dry. Allowing it to dry kills more bacteria on the skin and prevents the alcohol from causing stinging when you drain the blister.
  2. Look for a packaged sterile needle in your first aid kit. If you don't have one, locate any clean needle or even a clean safety pin. Sterilize the needle for 10 seconds in a flame. Don't burn yourself in the flame or you will now have blisters on your hand as well as your foot.
  3. Puncture the edge of the blister near the skin. You want to create the smallest possible hole—you don't want a large hole or a cut. Every opening in the skin increases the risk of infection.
  4. Apply gentle pressure to squeeze out the blister fluid.
  5. Do not remove the top of the blister or rub it off.
  6. Apply an ointment (such as petroleum jelly or an antibiotic ointment). Do not apply alcohol or iodine.
  7. Cover the drained blister with sterile gauze or a bandage.
  8. Discard the needle into sturdy plastic or metal container. Don't keep it to reuse.
  9. Keep the bandaged area clean and protected.
  10. Switch to shoes or sandals that won't rub against the area of the blister while it is healing.
  11. Change the gauze or bandage daily and check for signs of infection (pus or redness).

When to Call the Doctor

If an intact blister appears to have opaque fluid inside, see the doctor as it may be infected.

If the fluid you drain from the blister is foul-smelling or looks like pus (is opaque and thick rather than watery), see a doctor as it may already be infected.

If ​pus or redness develop after draining the blister, seek medical attention. Those are signs of an infection, and the sooner you get it treated, the better.

The foot and toes can be hard to treat effectively when infected and you risk gangrene.

While Your Blister Is Healing

The blistered area will probably hurt and you'll find your gait will be affected as you naturally try to protect it and reduce the pain. As a result of this altered walking or running pattern, you can expect to end up with sore muscles.

It often takes about a week for a blister to heal well enough to leave it unbandaged. You can expect the area to be prone to getting a blister again for at least two weeks, so you need to take precautions.

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Article Sources
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  1. U.S. National Library of Medicine. Blisters. Updated February 27, 2019

Additional Reading
  • Blisters: First Aid. Mayo Clinic.

  • Brennan FH. Treatment and Prevention of Foot Friction Blisters. ACSM's Health & Fitness Journal. November/December 2013. Volume 17, Issue 6 p.45-46. doi: 10.1249/FIT.0b013e3182a95110