There are three causes of headache caused by toothache: first, pain caused by infectious oral diseases such as pulpitis or periapical infection, which radiates from the trigeminal nerve distribution area to the ipsilateral upper and lower teeth and head and face, so patients may feel toothache, but also often feel pain in the ipsilateral half of the face and head, temples and other parts; second, interstitial infection caused by local infection such as periodontitis or periapical infection, which leads to intracranial infection through blood retrograde, and can lead to headache. Third, interstitial infections such as pulpitis, periapical infection or periodontitis can cause local venous sinus thrombosis, such as infected cavernous sinus thrombosis or sigmoid sinus thrombosis, etc. The thrombosis can lead to poor venous return and increased intracranial pressure, which can lead to the risk of headache. Therefore, in this case, the oral infection should be actively treated to prevent retrograde to the skull or the formation of thrombus. Once the effect of active local infection control is not satisfactory, further head MRI or head MRI venography should be done to exclude intracranial infection or intracranial venous sinus thrombosis, and active treatment should be taken in time.