Cucumber slices are a popular home remedy for soothing sunburns. By applying cucumber slices on sunburned skin, you can experience a cooling effect that may help alleviate discomfort without the need for commercial products. Cooling effect How cucumber slices work on sunburn Cucumbers are mostly water, which makes them an ideal cooling agent. The low temperature of the cucumber slices helps constrict blood vessels, which may lessen redness and inflammation associated with sunburn. Application tips How to apply cucumber slices effectively To use cucumber slices for sunburn relief, first chill them in the refrigerator for about 30 minutes.