CAUSES OF HEADACHE

Causes of Headache includes:

Infection
Common cold
Flu
Fever - headaches are common with fever from any type of infection
Ear infection
Dental conditions
Sinus infection
Pneumonia
Measles
Mumps
Tonsillitis
Sinus blockage
Coughing - too much coughing can cause a form of traction headache.
Various possible types of headache:
Migraine
Cluster headache
Tension headache
Hangover
Excessive alcohol
Stress
Fatigue
Tension
Tiredness
Excessive smoking
Dyspepsia
Eye conditions
Glaucoma
Medical procedures
Spinal tap treatment
Systemic or metabolic conditions
Hypertension
Thyroid disease
Anemia
Kidney failure
Uremia
Lead poisoning - or mild lead exposure from paint or car
Various toxins - see toxin causes of headache
Brain or head conditions
Meningitis
Encephalitis
Head injury
Brain injury
Mild traumatic brain injury
Concussion
Temporal arteritis
Heatstroke
Blood clots - in the brain, these can cause a stroke.
Brain aneurysm
Subdural hematoma
Stroke
Transient ischemic attacks
Subarachnoid hemorrhage
Brain tumor
Benign intracranial hypertension
Trigeminal neuralgia
Psychogenic pain syndromes
Congestion
Hyperemia
Dental conditions
Ear conditions
Nasal conditions

The follow list shows some of the possible medical causes of Headache that are listed by the Diseases Database:
Intracranial space-occupying lesion
Acute angle-closure glaucoma
Quinidine
Skull fracture
Nifedipine
Polycythaemia rubra vera
Cholesteatoma
Quinine
Adenoiditis
Enalapril
Migraine
Malignant hypertension
Ramsay Hunt syndrome
Bromocriptine
Pergolide
Methimazole
Sodium nitrite
Carcinoid tumours and carcinoid syndrome
Ondansetron
Tongue cancer
Campylobacter jejuni
Systemic lupus erythematosus
Intracranial abscess / granuloma
Superior vena cava obstruction
Fenoldopam
Posterior communicating artery aneurysm
Primary affective disorder
Hypercalcaemia
Eclampsia
Otitis externa
Vascular headache
Decompression sickness
Acute disseminated encephalomyelitis
Dental sepsis
Cyanides
Zafirlukast
Phaeochromocytoma
Spinal autonomic dysreflexia
Vardenafil
Isosorbide dinitrate
Subarachnoid hemorrhage
Lead
Hepatic failure
Meningoencephalitis
Premenstrual syndrome
Modafinil
Fluoxetine
Cyclosporin
Spontaneous intracranial hypotension
Idiopathic intracranial hypertension
Isosorbide mononitrate
Aminophylline
Granisetron
Posterior cervical sympathetic syndrome
Cluster headache
Propylthiouracil
Thiamine (Vitamin B1) deficiency
Cerebral venous sinus thrombosis
Epidural haemorrhage
Acoustic neuroma
Epinephrine
Pre-eclampsia
Familial hemiplegic migraine
Polymyalgia rheumatica
Raised intracranial pressure
Vertebral artery dissection
Upper respiratory tract infection
Ethanol
Head injury
Glyceryl trinitrate
Intracranial haemorrhage
Metronidazole
Anxiety disorder
Menopause
Amantadine
Vertebro-basilar artery syndrome
Influenza
Suppurative otitis media
Amphotericin B
Amlodipine
Carotid artery dissection
Stress headache
Amiodarone
Hyponatraemia
Mucormycosis
Posterior leucoencephalopathy syndrome
Tympanic membrane rupture
Dolasetron
Sinusitis
Carbimazole
Cerebrovascular accident
Pituitary tumour (growth hormone secreting)
Paroxysmal hemicrania, chronic
Temporal arteritis
Combined oral contraceptive pill
Lumbar puncture
Sildenafil
Functional disorders
Hypoglycemia
Cavernous sinus thrombosis
Q fever
Altitude sickness, acute
Relapsing fever
Pituitary apoplexy
Digoxin
Heat stroke
Carbon monoxide toxicity
Anemia
Interleukin 2
Thallium
Cervical spondylosis
Takayasu's arteritis
Hydrogen sulfide
Ergotamine
Yellow fever
Caffeine
Wegener's granulomatosis