As soon as the skin is frozen, it looks white. With thawing, redness appears. Intensity of freezing, skin colour, location, and cold sensitivity are some of the features that will determine the local redness.

Redness can appear immediately and last a few days. It is more obvious in fair skin and infants. It can last from several hours up to several days, depending on the depth of the procedure. For procedures of the face, make sure your patient knows about this redness: some patients feel a sudden concern about the way they will look immediately after leaving the office.

The sensation of cold is followed by discomfort and, with sufficient freezing, pain. Superficial freezing tends to be well tolerated by most people. Freezing has an anaesthetic effect. This allows multiple superficial treatments in one session or a cryobiopsy (Chap. 7). Even probe treatment in haemangiomas, which lasts a few seconds, is well tolerated by most children. Freezing larger lesions hurts more than several small ones. Face lesions tend to be very well tolerated, while scalp or earlobe lesions tend to be more painful; periungual and perianal treatments can be painful as well.

Freezing of lesions in the temples or the scalp in general can cause a strong headache in certain patients. This pain can last 30 min or more. In general, pain sensation relates to freezing depth and freezing time, anatomical location, cultural background, and gender [1].

While freezing gives a discomfort sensation, thawing can be quite painful. In thawing, oedema sets in the nerves and gives a painful sensation. This is the reason why a patient seems to have tolerated the freezing procedure relatively well and suddenly has a painful sensation that takes seconds but can be quite annoying. Let patients sit and wait through it in order to avoid syncope or a vasovagal reaction.

Certain areas are more sensitive than others and certain patients are more sensitive in general. There are cultural differences in pain perception. Children are surprising: some are very scared just by the presence of a physician, while others will be still and quiet during a cryosurgical session.

Some patients present wheals immediately after freezing. These wheals include the lesion in the central area and extend a few millimetres outwardly, giving an impression of a raised lesion above the skin surface. They tend to disappear in the subsequent 2 h.

Giménez-Arnau et al. [2] have proposed the term ultra-freeze urticaria to describe an acquired localized cold urticaria in patients who develop wheals and erythema within 5–10 min of the procedure. Their group of patients presented negative standardized tests for classical cold urticaria and positive skin pathology changes of urticaria. They propose further studies to help recognize this subset of patients as well as using liquid nitrogen (LN) as a potential new tool to diagnose cold contact urticaria.

Oedema is an expected secondary effect of cryosurgery. It directly relates to depth of freezing, skin type, age, and anatomical area differences. An 80-year-old Caucasian patient treated with a close technique in the eyelids will probably have significant oedema compared to a 30-year-old patient with Fitzpatrick skin type 3 with the same procedure done in the arm.