How To Tell If Your Blister Is Infected, And What To Do About It

by Rebecca Rushton

If getting a blister isn’t bad enough, the last thing you need is an infection. Infected blisters will get worse before they get better. They’re more painful, take longer to heal and as you'll see at the end of this article, can lead to some very nasty consequences.

 

What does a "healthy" blister look like?

A normal healthy blister contains thin watery blister fluid that is colourless or a very light yellow colour. Blister fluid can turn pink or red in the case of a blood blister. This does not mean your blister is infected. If just means damage has occurred to a small blood vessel and blood has leaked into the blister. All of these blister presentations are considered normal and uninfected.

Normal healthy uninfected blister

What does an infected blister look like?

There are some tell-tale signs that your blister is infected.

  • Pus: Instead of thin colourless blister fluid, an infected blister contains a thicker cloudy yellow or green fluid called pus.
  • Redness: The immediate area of skin around the blister is often red and this redness worsens over time.
  • Swelling: The immediate area of skin around the blister may be a bit puffy and this swelling worsens over time.
  • Pain: There will likely be increased tenderness that gets worse rather than better over time.

Infected toe blister with pus

How to treat an infected blister

Most infected blisters can be treated at home without the need for medical consultation. It’s very easy to do yourself – you just need the right products and to be diligent in monitoring your blister for changes. Here’s what you need to know…

 

Products you’ll need:

  • Clean hands – wash with soap and water or rubbing alcohol
  • Sterile lancing implement – I like using a scalpel blade or hypodermic needle. Don’t use a heated pin or sewing needle over a flame for these reasons.
  • Cotton buds – To gently ease any blister fluid out, to wipe debris from your blister and to apply your antiseptic / antibiotic.
  • Cottonwool or gauze – To wipe debris from your blister, soak up any blister fluids and dry your blister before applying your dressing.
  • Antiseptic or antibiotic – Either antiseptic solution such as povidone iodine, or antibiotic ointment such as Neosporin. Along with your body’s immune system, these products will kill the germs in your blister.
  • Island dressings – To protect the blistered skin and keep new germs out.

Don't have all these things on hand? Not a problem! We've packed them all up in our Sterile Blister Lance Pack. You can buy this today - click the button below for more details.

Sterile blister lance pack

 

Treatment procedure for intact, torn or deroofed blisters

👉 If your infected blister is deroofed, simply wipe any debris away, apply your antiseptic/antibiotic and cover it with an island dressing. Don’t forget, we’ll be monitoring it closely over the next few days.

👉 If your infected blister is torn, be sure to remove as much debris as you can from under your remaining blister roof. This debris is harbouring the very bacteria you are trying to kill, so physically removing it is a high priority. It may be necessary to deroof your blister for this reason. Either way, make sure your antiseptic/antibiotic gets into all the nooks and crannies under your blister roof. I like to use a liquid for this reason.

👉 If your infected blister is intact and full of pus, it is advisable to lance and drain the infected blister, and then follow the above steps. I have several videos on this page showing you how to perform this lancing procedure easily, safely and painlessly.

 

The importance of monitoring your infection

Your infection won’t clear up immediately after one episode of the above procedures. In fact, the infection may not clear at all. That’s why we have to monitor our infected blisters closely and repeat the above procedures.

How often? Twice a day should be enough. Change your dressing more often in the following situations:

  • Your dressing gets wet – The last thing you need is a soggy dressing sitting on your infected blister all day. Take the wet one off, apply some more antiseptic/antibiotic and put a nice clean one on.
  • You notice strikethrough – Strikethrough is evident when your blister exudates (fluid, pus, blood etc) have soaked right through the island of your dressing. As soon as strikethough happens, bacteria can travel through your dressing. Take the dirty one off, apply some more antiseptic/antibiotic and put a nice clean one on.

 

Medical urgency required

Infected blisters can morph into a more urgent situation that requires medical attention. At this point, you’ve not managed to get on top of this infection and the infection is spreading from the immediate area to involve other bodily systems and functions. Here’s when you should see a doctor *that day* with your infected blister:

  • If after 3 days your blisters continue to become more red, swollen, painful and weepy.
  • If you see reddish streaks radiating from your blister.
  • If you have a fever or chills

 

Possible complications

An unchecked blister infection can lead to serious health conditions. People have actually died or lost limbs due to infected blisters. President Coolidge's son Calvin Jr. died at 16 years of age in 1924 due to an infected blister on the top of his 3rd toe right foot from playing tennis with his brother. At this time, penicillin was yet to be discovered. In the modern day, blisters are often the starting point of an amputation in people with diabetes and peripheral neuropathy.

Here's what you need to know...

Lymphangitis: Red streaks around your blister indicate lymphangitis. This isn’t blood-borne infection, but the infection is starting to spread into the superficial lymphatic vessels. While not serious just yet, it’s a warning that you need to see a doctor about this infection today. If you don’t, the following more serious health conditions may result.

Lymphangitis
Lymphangitis - red streaks eminating from the source of the infection (James Heilman, MD)

 

Cellulitis: Cellulitis is a serious and painful skin infection that occurs when bacteria penetrate into deeper layers of the skin. It often requires hospitalisation and oral or intravenous antibiotics.

Cellulitis
Cellulitis (Flickr mikeblamires/125281197) - The black line has been dawn. With cellulitis, the demarkation between affected and unaffected skin is often quite definite.

 


Bacteremia: This is the medical term for blood-borne infection. The bacteria have entered the bloodstream and now passing through your organs.

Sepsis: By now, you are really crook, and you'll know it! In fact you might not know much about anything at this stage due to your altered mental state, along with the fever, low body temperature, rapid heartbeat and breathing difficulties. These symptoms are all part of the infection's assault on your organs. Urgent specialist medical care is required. Call an ambulance!

Moral of the story

Look after your blisters!

 





Rebecca Rushton
Rebecca Rushton

Author

Podiatrist, blister prone ex-hockey player, foot blister thought-leaderauthor and educator. Can’t cook. Loves test cricket.


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