Cryotherapy (liquid nitrogen)
Cryotherapy uses liquid nitrogen to treat warts and other skin lesions. Cryotherapy works by freezing the lesion, causing direct damage to the lesion, eventually removing it. It does not prevent them from developing in the future.
Commonly treated conditions
Cryotherapy is commonly used to treat many non-cancerous (benign) skin lesions. The most commonly treated conditions include:
- sun spots (also called actinic keratoses or solar keratoses)
- warts and verrucas
- genital warts
- seborrhoeic keratoses — a harmless warty skin growth and a common sign of ageing
- molluscum contagiosum — painless bumps causes by a virus.
Cryotherapy to treat skin cancer
It is also used to treat Bowen's disease — an easily curable early form of skin cancer.
Occasionally, a specialist skin doctor (a dermatologist) may suggest using cryotherapy to treat a small skin cancer.
How cryotherapy is done
Cryotherapy is a routine procedure that your healthcare provider or dermatologist can do.
They will spray liquid nitrogen onto your lesion. You may feel minor stinging or pain during or after the procedure. You do not usually need a local anaesthetic. Sometimes liquid nitrogen can be applied using a cotton tipped applicator.
Freezing lasts a few seconds, depending on how thick the lesion is. Sometimes you need a repeat treatment or regular treatments.
The treated area will usually become red immediately after the procedure. A scab may form over the next few days, which will drop off over the following 1 or 2 weeks.
A blister can sometimes form, filled with clear, red or purple fluid.
After cryotherapy
You do not usually need any treatment during the healing phase after cryotherapy. If you do, your healthcare provider will tell you.
If you have had genital warts treated, you should avoid sexual contact with the treated area.
You do not need to put a dressing over the area unless your clothes rub on it or it could get knocked or injured.
Wash and dry the area gently once or twice a day.
If you need pain relief, use a medicine like paracetamol.
Risks and side effects of cryotherapy
Cryotherapy is generally safe. Other than immediate side effects such as pain, redness and blistering, the main side effect is the risk of infection. This is when the treated area becomes red, swollen, painful and pus appears.
Other potential side effects include:
- delayed healing
- scarring (including a white patch)
- damage to the underlying skin
- nerve damage (this is rare)
- getting the lesion again.
If you are concerned about infection or anything else after cryotherapy, ask your healthcare provider to check the treated area.