Drying your hair with a hairdryer does not damage your hair as long as you keep the hairdryer 15cm away and use continuous motion, according to a study from the Department of Dermatology and Institute of Hair and Cosmetic Medicine in Wonju, Korea.
The researchers assessed the changes in hair structure, morphology, moisture and colour after repeated shampooing and drying with a hairdryer at a range of temperatures with a standard drying time of 30 minutes. There were five test groups, including no treatment, drying at room temperature, drying with a hairdryer for 60 seconds at 15cm, drying with a hairdryer for 30 seconds at 10cm and drying with a hairdryer for 15 seconds at 5cm. The hotter the drying temperature, the more damage was caused to the hair shaft.
Lee Y, Kim YD, Hyun HJ et al. Ann Dermatol 2011; 23(4): 455-62