"THINK Trial: Treatment of Headache With IntraNasal Ketamine: A Randomized Controlled Trial Evaluating the Efficacy of Intranasal Ketamine Versus Standard Therapy in the Management of Primary Headache Syndromes in the Emergency Department"

Inclusion Criteria:

1. Chief compliant of a benign, non-life threatening headache that the PI/AI believe will require parental analgesia for management.
2. Ability to comprehend, speak, read, and write in the English language

Exclusion Criteria:

1. Age less than 18 and greater than 65
2. History of hypersensitivity to Ketamine, diphenhydramine, metoclopramide, ketorolac or dexamethasone
3. Weight less than 45 kg or more than 115 kg
4. Pregnancy or lactating female.
5. Patient is female of child-bearing age and unwilling to provide urine or blood for HCG analysis
6. Altered mental, diminished decision making capacity
7. Poor vital sign stability Hypoxia: O2 \< 92%, Hypotension: SBP\< 80 Hypertension: SBP\>220 Heart rate: \< 50 or \>150 Respiratory Rate: \<8 or \>30
8. Presence of chronic oxygen-dependent pulmonary disease, liver cirrhosis, or renal disease requiring dialysis
9. Presence of ischemic heart disease, heart failure, or a history of unstable dysrhythmias
10. History of schizophrenia, psychosis or hallucinations (as assessed by electronic chart review)
11. History of alcohol or drug abuse
12. History of intracranial hypertension
13. History of glaucoma
14. History of HIV or immunosuppression
15. Presence of intracranial mass or vascular lesion (defined as inclusion criteria 1. As benign headaches)
16. Poorly controlled thyroid disease
17. Concomitant infections
18. History of pheochromocytoma
19. History of epilepsy
20. History of active bleeding or those receiving anticoagulants.