In reality, most blisters don’t have blood in them. Repeated heavy pressure (friction) or simply long periods of pressure can turn an ordinary blister into a blood blister.
The fluid will go from clear to light pink, and with continued pressure, to blood red.
The general rule of thumb is not to lance and drain any blood blister. You may have to pad the area to take the pressure off the blood-filled skin. You need to now how to manage a ruptured blood blister.
Here’s why. The problem with blood blisters is that by draining them, the athlete’s circulatory system is opened to possible infection. In a sterile environment or at your home, this may not be an issue. However out on a trail, or somewhere where the athlete may be unable to keep his feet clean, it’s a different story. Where the blister is on the foot can present more problems. A blood blister on the side of the heel is not as problematic as one on the bottom of the foot. The opened blister is exposed to dirt, grime and any bacteria on whatever is touching the skin. Blood blister must be treated as wounds.
Another issue is whether the athlete has he right supplies in his foot care kit to patch the blister. Opening it up and not applying antibiotic ointment and a covering it is a huge mistake.
I tell athletes that normally blood blisters are not lanced because that is the wise thing to say. If everyone thinks they can simply lance them, without fully understanding how to care for them, we’ll have a lot of people with infected feet.
At Badwater last year we had a runner with a very large heel blood blister. She was from Brazil and would be flying home – but she was also a diabetic. Because of her diabetic status, we declined to lance the blister. It would not have been safe.
The photo here is from last week’s Badwater Ultramarathon in Death Valley. The runner had completed the 135-mile race. I talked to him at the finish line and told him the pitfalls of lancing a blood blister. I told him to shower and be careful of popping it and to come see us in the medical room if it did pop. It popped when he was in the shower, the best of all places.
I cleaned the area with alcohol wipes and lanced the blister with a #11 scalpel. I made three cuts so any more fluid would be forced out as he walked. I expelled the blood and applied a generous layer of antibiotic ointment. A gauze 4×4 was placed over the top and then the foot was wrapped with Coban, a wrap material that sticks only to itself. I gave the runner a Zip-Lock bag with a small tube of ointment, several more 4x4s, a Popsicle stick to apply the ointment. I told him he could unwrap the Coban and reuse it multiple times. Then I asked him if his Tetanus was up to date after which I gave him the usual infection speech.
Recheck the blister three times a day for signs of the infection. Each time you check, apply a new coating of antibiotic ointment and change the dressing. Early treatment can keep the infection from becoming more serious.
An infected blister may be both seen and felt. An infection will be indicated by any of the following: redness, swelling, red streaks up the limb, pain, fever, and pus. Treat the blister as a wound. Clean it frequently and apply an antibiotic ointment. Frequent warm water or Epsom salt soaks can also help the healing process. Stay off the foot as much as possible and elevate it above the level of your heart. If the infection does not seem to subside over 24 to 48 hours, see a doctor.
It’s wise to keep a tube of antibiotic ointment in your foot care kit. You may never get a blood blister, but then again, you might. And if you get one, it may not rupture, but then again, it might.
It’s better to be prepared by knowing how to care for blood blisters.