Cryotherapy, also known as cryosurgery or cryoablation, is a minimally invasive dermatological procedure that involves the controlled application of extreme cold to treat various skin lesions. This technique uses cryogens—substances capable of producing very low temperatures—such as liquid nitrogen, carbon dioxide snow, and dimethyl ether and propane (DMEP). Among these, liquid nitrogen, which reaches temperatures as low as –196°C, is the most commonly used and effective agent in clinical practice.
This treatment method is widely regarded for its simplicity, cost-effectiveness, and safety, making it particularly suitable for outpatient settings. Cryotherapy is frequently employed to manage benign skin conditions such as actinic keratoses, seborrheic keratoses, viral warts, molluscum contagiosum, and skin tags. In some instances, it is also used to treat small, superficial skin cancers, including superficial basal cell carcinoma and in-situ squamous cell carcinoma located on the trunk and limbs. However, because the success rate can vary, patients undergoing cryotherapy for malignant lesions must be followed closely for signs of recurrence.
Cryotherapy is contraindicated in certain situations. It should not be used on undiagnosed skin lesions or melanomas, as histopathological confirmation may be necessary. It is also avoided in individuals with darker skin tones due to the risk of hypopigmentation, as well as in areas with compromised circulation, and in patients with a history of poor wound healing or adverse reactions to cryotherapy. Children, unconscious patients, and individuals with cold-sensitive conditions such as Raynaud disease, cryoglobulinaemia, or cold urticaria should not undergo this procedure.
The therapeutic effect of cryotherapy relies on freezing the targeted tissue to sub-zero temperatures. When applied, the cold causes rapid formation of ice crystals within cells, leading to membrane rupture and ultimately, cell death. Application techniques vary based on the characteristics of the lesion. For example, in the timed spot freeze or direct spray method, the liquid nitrogen spray is administered to the centre of the lesion from a short distance until an ice ball forms that extends slightly beyond the lesion’s margin. Depending on the lesion’s type and location, the freeze is maintained for 5 to 30 seconds. In some cases, a double freeze-thaw cycle may be used to enhance efficacy. Other delivery methods include using cotton-tipped applicators, cryoprobes, or paintbrush techniques.
In addition to liquid nitrogen, cryotherapy can also be performed using carbon dioxide, which is frozen into a cylinder or mixed into a slush with acetone and applied directly to the lesion. Over-the-counter treatments for warts may use DMEP, which is dispensed from an aerosol canister onto a foam applicator and applied to the lesion for up to 40 seconds.
Cryotherapy has proven to be effective for several skin conditions. For actinic keratoses, a single freeze-thaw cycle may be sufficient, with reported cure rates ranging from 39 to 83 percent. Seborrheic keratoses may require longer or repeated treatments, especially if the lesion is thick. Viral warts may necessitate multiple sessions, particularly when lesions are hyperkeratotic or large, and pre-treatment with keratolytic agents may improve outcomes. While cryotherapy is not the first-line treatment for basal or squamous cell carcinomas, it may be considered for small, low-risk tumors. In such cases, multiple freeze-thaw cycles are used, with ice margins extending 3 to 5 millimeters beyond the lesion, and recurrence rates range from 6 to 34 percent.
Although cryotherapy is generally well tolerated, it is not entirely free of side effects. Immediately following treatment, patients may experience pain, swelling, blistering, or paraesthesia. Delayed effects can include ulceration or bleeding, and complications such as local infection, nitrogen emphysema, or temporary nerve damage may also occur. In some cases, permanent hypopigmentation, atrophic scarring, or localized hair loss may result, particularly in cosmetically sensitive areas.
Post-procedural care is straightforward but essential for optimal healing. Patients are advised to gently clean the area with soap and water once or twice daily. While dressings are typically optional, they may be recommended for areas that are prone to friction or trauma. Topical corticosteroids and oral aspirin can help alleviate swelling and discomfort. Blistering, a common and benign outcome, should not be punctured, and scabs should not be picked to avoid scarring. Healing times vary depending on the treated area and lesion type, but most patients recover within one to three weeks.
Cryotherapy remains a versatile and effective treatment for a range of dermatological conditions. When performed by trained professionals and appropriately selected for the patient and lesion type, it offers high success rates with minimal complications. For best outcomes, patient education, appropriate follow-up, and individualized treatment planning are key.
