What is the ruling on accidentally pulling out a single hair during احرام?

If a single hair falls out unintentionally — such as during وضو or while scratching — there is no sin and no fidyah is required. Sheikh Ibn Baz stated: 'If hairs fall out without intention during washing or combing, there is no harm.' The prohibition is on deliberately cutting or removing hair. If a حاجی deliberately removes three or more hairs, he must offer fidyah (the choice between fasting three days, feeding six poor people, or sacrificing a sheep).