Tension Headache: This is often the most common cause of facial pain in young adults, characterized by a dull, aching sensation, usually bilateral but can be unilateral, and is associated with muscle tension.

Migraine: Can cause unilateral facial pain, often accompanied by other symptoms such as nausea, vomiting, photophobia, and phonophobia.
Trigeminal Neuralgia: Although less common in young adults, it can cause severe, sharp, stabbing pain in one side of the face, typically triggered by light touch or eating.
Sinusitis: Inflammation of the sinuses can cause facial pain, especially if the maxillary or frontal sinuses are involved, often accompanied by nasal congestion and purulent discharge.
Temporomandibular Joint (TMJ) Disorder: Can cause pain in the jaw and face, often associated with clicking of the jaw, difficulty chewing, and jaw tenderness.

Acute Angle-Closure Glaucoma: A medical emergency that can cause severe, unilateral facial pain, typically around the eye, accompanied by blurred vision, nausea, and vomiting.
Cavernous Sinus Thrombosis: A rare but potentially life-threatening condition that can cause facial pain, especially if accompanied by symptoms such as fever, ptosis, and ophthalmoplegia.
Multiple Sclerosis: Although rare, can present with facial pain, especially if associated with other neurological symptoms such as numbness, weakness, or visual disturbances.

Raeder's Syndrome: A rare condition characterized by unilateral facial pain, ptosis, and miosis, often associated with a Horner's syndrome.
Eagle's Syndrome: Caused by an elongated styloid process, can cause sharp, stabbing pain in the face and throat, often triggered by swallowing.
Glossopharyngeal Neuralgia: A rare condition that can cause sharp, stabbing pain in the throat and face, often triggered by swallowing or chewing.