Migraine: This condition can cause eyelid ptosis due to involvement of the oculomotor nerve and is often accompanied by headache. The ptosis in migraine is usually transient and resolves with the headache.

Cluster Headache: Cluster headaches can cause ptosis on the same side as the headache due to autonomic features associated with the condition. The ptosis is typically accompanied by other autonomic symptoms like lacrimation and nasal congestion.
Horner's Syndrome: This syndrome, which can result from various causes including stroke, can present with ptosis, miosis, and anhidrosis. Headache may not be a primary symptom but can occur depending on the underlying cause.
Sinusitis: Inflammation of the sinuses, especially the sphenoid sinus, can cause headache and, if it affects nearby nerves, potentially lead to eyelid ptosis.

Aneurysm (e.g., Posterior Communicating Artery Aneurysm): An expanding aneurysm can compress the oculomotor nerve, leading to ptosis and potentially severe headache. This is a medical emergency.
Stroke or Transient Ischemic Attack (TIA): Certain types of stroke, especially those affecting the brainstem or the nerves supplying the eye, can cause sudden onset of ptosis and headache.
Giant Cell Arteritis: This condition can cause headache and, if it involves the nerves around the eye, potentially lead to ptosis. It's a medical emergency due to the risk of vision loss.

Myasthenia Gravis: An autoimmune disease that can cause fluctuating muscle weakness, including eyelid muscles, leading to ptosis. Headache is not a primary symptom but can occur.
Mitochondrial Myopathies: Certain mitochondrial disorders can cause chronic progressive external ophthalmoplegia, which includes ptosis, and may be associated with headache due to other systemic symptoms.
Tolosa-Hunt Syndrome: A rare condition characterized by headache, ophthalmoplegia (including ptosis), and other cranial nerve palsies due to nonspecific inflammation in the cavernous sinus or superior orbital fissure.