Should I drain a liquid nitrogen wart blister?

Question:

I got a blister when I recently tried the liquid nitrogen treatment to freeze a wart on my foot. It is tender and so I stopped running. Should I try to drain the blister so I can run?

Answer:

The idea with treating a wart with liquid nitrogen is in fact to cause a blister. The way this treatment works is that when liquid nitrogen freezes the skin fluid collects between the dermis and the underlying subcutaneous layer of the skin creating the blister. The blister separates the skin layers. Here is how it cures a wart...

The wart is a thick callus covering an encapsulated collection of viral wart particles, which is within then the living layer of skin called the dermis. By creating a blister beneath the dermis (under the wart) the wart essentially gets lifted off of the underlying skin as the blister swells up.

The fluid within the blister will resorb over the next several days. As the blister heals and flattens out, it forms a scab-like structure that doesn’t fully re-adhere to the tissue underneath. Eventually the dried up skin of the blister peels off, and the wart goes with it. If all goes according to plan, you are left with new healthy skin underneath. 

There are many different blistering agents that can be used to cure plantar warts. Here are three of the most common wart treatments that work by blistering:

Liquid Nitrogen - creates a blister with a carefully placed frostbite-type injury. 

Bleomyocin - is a chemical blistering agent injected directly into the wart.

Canthacur - is a topical chemical blistering agent applied to the surface of the wart.

As every runner knows, blisters on the feet can be irritating enough to force one to limit their run mileage or stop running altogether. So it is not surprising that a runner may consider popping a painful blister to lessen the discomfort, promote healing and get back to running. 

This may be a reasonable strategy with friction blisters sustained during a marathon or other long run. But not so with warts treatment blisters.

The problem with warts is that they are caused by a viral infection of the skin. If you poke a needle through the blister (and through the wart containing all of those viral particles) you just might seed the surrounding healthy, non-infected skin with the wart virus. In this way, by attempting to drain the blister under the wart, you may actually infect other areas of the foot and cause a new wart to start growing nearby. 

Then, after the original wart (and its associated treatment blister) have gone away, you may have a brand new nasty little wart rearing its ugly head. Then you have to repeat this process all over again.

Another issue is that the fluid inside the blister is sterile. As soon as you poke a hole the blister fluid can drain out, but bacteria can also get in. So when you pop a blister the risk of bacterial infection goes up. 

If you have a wart that is being treated by a podiatrist, and the blister is large enough to interfere with your activities, you should follow-up with the treating physician. After all the doctor is being paid to treat the wart, so let the doctor finish what he started. Let your podiatrist decide whether or not to drain the blister, and do the draining if needed. That is the safest way to remedy the blister AND make sure that there isn’t any risk of causing a bigger problem long-term.

Heal fast and get back to running! 

Dr. Christopher Segler is a podiatrist who focuses on the rapid treatment of running injuries. He is a runner himself and 10-time Ironman Triathlon finisher. You can learn more about warts, blisters and running injuries at AnkleCenter.com and DocOnTheRun.com  If you have a question about a running injury, you can reach him directly at 415-308-0833.