Degrading characteristics of InGaN/GaN-based blue light-emitting diodes (LEDs) in the optical increase stage (stage I) were investigated. The LEDs were under an ageing with dc current of different levels. Different ageing phenomena were observed for both the electrical and the optical characteristics. The tunnelling components of the forward current were found to change with different trends for the samples aged under current stresses of 100 mA and 1000 mA, respectively. The former decreased monotonically, while the latter decreased in the early period, and then kept increasing. Different ageing rates but the same trends were observed for the optical degradation of the samples aged under different stresses. The ageing factors induced by the dopant activation and the change of defects competed with each other in the ageing process and were proposed to be responsible for the ageing characteristics.