Hadith 8:215
Abu Bakr narrated to us, he said: Jarir narrated to us, from 'Ata', from Mujahid, he said: There is no harm in the Muhrim (a person in the state of Ihram) washing his head in water.
حدثنا أبو بكر قال ثنا جرير عن عطاء عن مجاهد قال لا بأس أن يغسل المحرم رأسه في الماء