Liquid nitrogen is a very cold substance which when applied to the skin usually produces a blister, similar to a burn. It is used to destroy surface changes or small lumps on the skin.
Liquid nitrogen therapy is a procedure carried out as an outpatient in the Dermatology outpatient area.
What are the immediate effects of Liquid Nitrogen Therapy?
The treatment hurts but this is not severe and local anaesthetics are not used.
After treatment you may experience some pain which should be easily controlled with simple pain relieving drugs, e.g. soluble aspirin for those over 16 years of age, or paracetamol. (Note: aspirin is generally not recommended for the under 16's because of the small risk of it provoking a reaction called Reye's Syndrome). The treated area may also swell and go red.
A blister often forms after treatment.
It is probable that 1-2 days after treatment a crusted or scabbed area will develop at the treated site. The area should be kept clean with soap and water and a simple dry dressing applied to protect clothing etc, or if this makes it more comfortable.
The area can be washed with soap and water. If a dressing is applied this must be removed before washing. If the dressing gets wet this must be removed because wet dressings make infection more likely.
The treated area may be red for several weeks after treatment but there is no need to apply cream or ointment of any description.
What are the long term risks of Liquid Nitrogen Therapy?
There is a risk of scar formation after liquid nitrogen therapy although this is unlikely unless a long freeze time has to be used to treat a skin cancer or viral warts on the sole of the feet.
In black or brown skin there is the risk of the skin becoming lighter (occasionally permanently) or darker. In most cases this colour change resolves eventually but may take months to do so.
Prolonged freeze times used on the fingers may damage nerves producing numbness or tingling. This damage is usually temporary.
Rarely other important structures, such as tendons and the growing part of the nail, may be damaged by liquid nitrogen therapy and your doctor would be happy to discuss these with you.
What about the treatment of viral warts with liquid nitrogen?
Liquid nitrogen therapy does not kill the virus that produces common warts. There is no guarantee that the treatment will remove the wart.
Repeated liquid nitrogen therapy given 4 times over a 12 week period has a 70% chance of getting rid of multiple hand warts.
Treatment is usually halted if the warts have not gone after 6 treatments.
Sometimes warts persist after liquid nitrogen therapy and very occasionally appear to spread beyond the treated site.