If you have this treatment, your doctor will freeze the wart for about 10 to 30 seconds using liquid nitrogen. You may need to have the treatment several times, depending on the type of wart you have and where it is on your body.  Your doctor will use a spray or a cotton wool bud to apply the liquid nitrogen. 
Studies on freezing have found different things. One big summary of research (a systematic review) found that freezing warts worked no better than using a cream that didn't contain any medicine. But other studies have found that freezing works for about half the people treated after one month to three months. 
Studies have also compared freezing with other treatments. One good-quality study (a randomised controlled trial) found that freezing worked better than salicylic acid for most types of warts.  However, several studies found that both treatments worked about the same for warts on the sole of the foot (verrucas).  
Other studies have found that simpler treatments like duct tape and photodynamic treatment work as well as, and may be better than, having warts frozen off by a doctor. 
Freezing can be painful. It can cause blistering and scarring.  Your doctor might scrape off the top layer of skin with a scalpel before freezing the wart or verruca. This can cause bleeding, and some people find it unpleasant. 
You can buy freezing treatments over the counter from a pharmacy. Brands include Scholl Freeze Verruca and Wart Remover and Wartner Wart and Verruca Remover. You freeze the wart yourself using a spray containing dimethyl ether and propane. These don't get as cold as the liquid nitrogen that doctors use. And very little research has been done on these treatments. We don't know whether they work, and they can't be prescribed by your doctor. 
randomised controlled trials
Randomised controlled trials are medical studies designed to test whether a treatment works. Patients are split into groups. One group is given the treatment being tested (for example, an antidepressant drug) while another group (called the comparison or control group) is given an alternative treatment. This could be a different type of drug or a dummy treatment (a placebo). Researchers then compare the effects of the different treatments.
A systematic review is a thorough look through published research on a particular topic. Only studies that have been carried out to a high standard are included. A systematic review may or may not include a meta-analysis, which is when the results from individual studies are put together.
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