From: Rabbi Moshe Sofer
To: Unknown recipient
Rabbi Akiva Eiger questioned whether combing hair near the pe'os is forbidden, since combing inevitably pulls out hairs and the stringent view prohibits any instrument that removes pe'os hair. The Chasam Sofer rules unequivocally that combing the pe'os area is completely permitted, vindicating universal Jewish custom and citing his own teacher Rabbi Noson Adler's practice; through multiple arguments he demonstrates that plucking or incidental hair removal through combing falls entirely outside the prohibition of hakafas harosh according to all authorities.
Source: Shu"t Chasam Sofer YD §139