Chinese cucumber (Trichosanthes kirilowii or related Cucumis species) has a history of use in traditional Chinese medicine (TCM), including for skin ailments such as sunburn. The traditional application is typically as a topical poultice or in the form of cucumber slices applied directly to the skin. This practice is based on the cooling and hydrating properties attributed to cucumber in TCM, where it is considered to "clear heat" and soothe irritated tissues.

However, scientific evidence supporting the efficacy of Chinese cucumber specifically for sunburn is minimal. Most available research about cucumber (Cucumis sativus) examines its general skin-soothing effects, anti-inflammatory properties, and high water content, which may provide temporary relief to minor burns and irritated skin. These effects are largely extrapolated from studies on common cucumber and may not exactly reflect the properties of Chinese cucumber. There are no robust clinical trials or systematic reviews confirming its benefit for sunburn treatment.

In summary, the use of Chinese cucumber for sunburn is primarily justified by tradition, with very limited scientific validation. Its main effects are likely due to its moisturizing and cooling properties, which may offer symptomatic relief rather than active healing of sunburned tissue.