▁about ▁ 8 4 8 ▁million ▁( 1 1 . 7 %). ▁ ▁C aus es ▁ ▁There ▁are ▁more ▁than ▁ 2 0 0 ▁types ▁of ▁head aches . ▁Some ▁are ▁har ml ess ▁and ▁some ▁are ▁life - th re aten ing . ▁The ▁description ▁of ▁the ▁head ache ▁and ▁find ings ▁on ▁ne uro log ical ▁exam ination , ▁determine ▁whether ▁additional ▁tests ▁are ▁needed ▁and ▁what ▁treatment ▁is ▁best . ▁ ▁Head aches ▁are ▁broad ly ▁class ified ▁as ▁" primary " ▁or ▁" second ary ". ▁Primary ▁head aches ▁are ▁ben ign , ▁rec urrent ▁head aches ▁not ▁caused ▁by ▁underlying ▁disease ▁or ▁struct ural ▁problems . ▁For ▁example , ▁mig raine ▁is ▁a ▁type ▁of ▁primary ▁head ache . ▁While ▁primary ▁head aches ▁may ▁cause ▁significant ▁daily ▁pain ▁and ▁dis ability , ▁they ▁are ▁not ▁dangerous . ▁Second ary ▁head aches ▁are ▁caused ▁by ▁an ▁underlying ▁disease , ▁like ▁an ▁in fection , ▁head ▁injury , ▁v asc ular ▁dis orders , ▁brain ▁ble ed ▁or ▁tum ors . ▁Second ary ▁head aches ▁can ▁be ▁har ml ess ▁or ▁dangerous . ▁C ertain ▁" red ▁flags " ▁or ▁warning ▁signs ▁indicate ▁a ▁secondary ▁head ache ▁may ▁be ▁dangerous . ▁ ▁Primary ▁ 9 0 % ▁of ▁all ▁head aches ▁are ▁primary ▁head aches . ▁Primary ▁head aches ▁usually ▁first ▁start ▁when ▁people ▁are ▁between ▁ 2 0 ▁and ▁ 4 0 ▁years ▁old . ▁The ▁most ▁common ▁types ▁of ▁primary ▁head aches ▁are ▁mig ra ines ▁and