How to Freeze a Wart With Liquid Nitrogen

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Liquid nitrogen is a simple, effective treatment for removing warts and moles commonly used by dermatologists. If you've already had warts treated in this way and feel comfortable with the procedure, you may consider doing it yourself. This article describes the procedure and how it works. Provided for informational purposes only. Not a substitute for qualified medical diagnosis or treatment.


How It Works
  1. Warts are fed by blood vessels. If you can damage and kill these blood vessels by freezing them, the wart will die. Eventually it will fall off. Liquid nitrogen is cold enough to bring about this localized freezing. We want to restrict the tissue damage to the smallest possible area.
  2. A blister will develop a few hours after freezing the wart. The wart will be raised slightly, redden, and you may feel a slight burning sensation.
  3. Do not break the blister. If the blister breaks, tissue underneath is likely to be re-infected and cause the wart to grow back.
  4. If you freeze the wart just the right amount, a small but visible blister will form. After some number of days, you will notice a reddish tint inside. Slowly the fluid of the blister will be re-absorbed. The blister will change to a darker color. As it dries out the skin will seem a bit thicker.
  5. Resist the temptation to pull off the dead skin. If you do, the wart is more likely to grow back. Even if you always pick your scabs and squeeze your pimples, you can and need to learn to wait in order to be free of your warts. When the dead skin and dried up wart core sloughs off on its own, you will have closed, healthy skin below.
  6. An advantage of this technique is that when done properly, the outer layer of skin is never broken, greatly reducing the infection risk compared to other techniques.
Procuring the liquid nitrogen
  1. This is easier than it sounds. Look in the phone book for suppliers of welding gases. Call them and ask if they can supply you with a small amount. If they ask for the reason, just say it is for a science experiment, which is truthful.
  2. Their next questions will be how much you need, and whether you have a dewar flask to transport it. The answers are "one litre" and "yes." A common vacuum flask (i.e. Thermos) will serve as your dewar flask and is a perfectly acceptable storage vessel for liquid nitrogen. Any quart-capacity glass or metal vacuum bottle will do. You may also rent a dewar from the supplier. Liquid nitrogen is cheap, and many places will give it to you for free.
  3. There are two precautions you need to remember to transport your liquid nitrogen safely:
    • Close the thermos using only a wad of paper towels, not the usual screw-in plug. Any cap used to hold the paper towels in place should be loose enough to allow vapors to escape, otherwise your thermos may explode. (If safe release of vapors is a concern, pay extra money to rent a dewar flask.)
    • Keep the thermos upright.
  4. You can keep the liquid nitrogen in a thermos or dewar for a couple days if necessary. If your friends have warts they want to get rid of, they can take advantage of your supply.
  1. Probably you want to observe basic hygiene, even though you are not planning to break the skin. Wash thoroughly.
  2. Before beginning, spend plenty of time looking at the wart. Pinch in the skin from the sides and below, so you can get an idea how deep the core goes and how big around it is. You're not thinking of the dead shell on top, but the living core inside. Pinch it and feel exactly how big it is underneath. If it's on the bottom of your foot, it may just appear as a small bump, but the core goes in much deeper. This first step is important, because you need to know how much tissue to freeze.
  3. To apply the liquid nitrogen, use a regular cotton bud (i.e. Q-tip), the same kind you use for cleaning your ears. As you get more experienced, you may want to tie some extra cotton wool around the base of the cotton bud to hold extra liquid nitrogen. This will save you from having to revisit the thermos so often.
Applying the liquid nitrogen
  1. Pour a small amount of the liquid nitrogen into a polystyrene cup. It is easier to dip the cotton bud and helps keep the liquid nitrogen in the dewar clean (which could matter if more than one person shares the flask.)
  2. Let's assume it's a small wart, about the size of a pea (4mm) or smaller. Apply the cotton bud right in the middle of the wart. Start with a light pressure. Repeat this several times until you start to see a frozen zone--it will be white in color. What's tricky is that while it may be frozen white on the surface, you need to think about how deeply it is frozen. So keep applying liquid nitrogen, doing it in such a way to keep the frozen zone from spreading into the healthy skin around the wart. As you freeze into the core of the wart, you'll be using a bit more pressure. You'll notice that the tissue has hardened, and if you pinch from the sides you will feel that there is frozen tissue between your fingers.
  3. After the wart seems frozen enough, give it rest. The color will slowly return. If you think it may not have been frozen deeply enough, you can repeat the process. There will be some minor spikes of cold pain. Major pain is a sign you're doing too much, or perhaps are severely frightened and therefore should leave off attempting this.
  4. Put a bandage (i.e. Band-Aid, or sticking plaster if you're British) over the wart to protect it if you like.
  5. You may need to repeat the procedure in a couple weeks for any warts that come back.


  • In the following video, you can see a special cryo tool in use. The freezing action is much faster than the manual procedure described here, however the principle is the same. Observe how the tissue turns white when frozen. Pay special attention to how the freezing sometimes spreads wider than the lumpy part of the wart. That's something to avoid as far as possible.


  • The procedure works best for smaller warts, about the size of a pea (4mm) and smaller. In principle, larger warts may be handled by freezing one pea-sized piece at the edge of the wart, then waiting for the skin to heal completely (about two weeks) before attempting a second freezing. Under no circumstances should you freeze wider areas, as this will result in a large, painful blister, with a real risk of infection.
  • This procedure may involve minor pain or discomfort. You may prefer to request the services of a dermatologist or it will grown into a dark brown ball because of the liquid nitrogen burn.
  • Warts on the weightbearing surfaces of the foot (plantar warts) deserve special consideration. Since this procedure causes a blister, performing it on a foot can lead to discomfort that interferes with normal walking and weightbearing. Also plantar warts tend to be deeper than other warts because the weightbearing action pushes them inside. You will need to freeze them more times, using less nitrogen on the cotton bud each time so that the freezing goes deeper and does not cause a wide blister.
  • This procedure is suitable for common warts or moles with a clearly defined boundary. There are other kinds of lumps that can be tumors of varying degrees of malignancy. You should be sure that your warts or moles are the harmless, slow-growing and non-invasive ones. You should consult a doctor if your wart or mole is large, grows quickly, changes color, looks inflamed or swollen, or is painful to the touch.
  • Liquid nitrogen can be dangerous. Laboratories using it for research require users to wear special cryo-gloves, goggles, gowns and shoes, and to follow special handling procedures.[1] . It is also an asphyxiation hazard: if knocked over in a closed space (e.g. a car or lift), a 2L container of liquid nitrogen can evaporate instantly and reduce the oxygen levels of 3 cubic meters of air down to 10%, an oxygen concentration at which a person can pass out and asphyxiate without warning. Such measures are not usually seen when visiting a doctor for cryogenic wart removal. The chief risks to the home experimenter are spills onto clothing and into shoes due to the wicking action of clothing that holds the liquid nitrogen in contact with skin. Splashes into the eyes are a concern because liquid nitrogen can spatter when it spills. Goggles (not safety glasses) are usually recommended. Spills onto bare skin are less of a risk. Due to the Leidenfrost effect, it is possible to briefly plunge one's hand into liquid nitrogen without injury.

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