The common causes of itchy face when sweating in summer are contact dermatitis and other skin diseases. 1. Contact dermatitis: because of the ingredients in sweat, such as urea, lactic acid will stimulate the facial skin, thus triggering contact dermatitis, the face will feel itchy. 2. Other skin diseases: summer sweating with increased oil secretion can lead to folliculitis or acne, if the facial skin itself has a history of folliculitis or acne, summer sweating stimulate the lesions of the skin, can make the face itchy. If your face itches when you sweat in the summer, you should go to a regular hospital in time to find out the cause of the disease and choose a suitable method of treatment under the guidance of a professional doctor.