What are the possible causes of an acute onset headache in a 38-year-old female with a history of obesity, taking tirzepatide and minoxidil, presenting with constant temporal region pain?

Acute Onset Temporal Headache in 38-Year-Old Female on Tirzepatide and Minoxidil

This patient requires immediate evaluation for secondary headache causes given the acute onset in someone with no prior headache history, particularly focusing on medication-related etiologies and life-threatening conditions before considering primary headache disorders.

Critical Red Flags Requiring Urgent Investigation

This presentation contains several concerning features that mandate careful evaluation:

• New onset headache in a patient with no prior headache history is a red flag requiring consideration of secondary causes 1
• Acute onset (2 days) warrants investigation for serious secondary headache disorders including subarachnoid hemorrhage, meningitis, and other potentially life-threatening conditions 1
• Age 38 years places her in a demographic where both primary and secondary headaches must be considered 1

Differential Diagnosis: Primary vs Secondary Causes

Most Likely Primary Headache Disorders

Migraine without aura is the most common primary headache disorder that could present with these features 1:

• Unilateral temporal location fits migraine criteria 1
• Moderate intensity (2-5/10) is consistent with mild to moderate migraine 1
• However, the absence of associated symptoms (nausea, photophobia, phonophobia) makes this less typical 1

Tension-type headache should be considered 1:

• Typically bilateral with pressing/tightening quality 1
• Mild to moderate intensity without aggravation by routine activity 1
• Lacks the accompanying symptoms of migraine 1

Critical Secondary Causes to Exclude

Medication-related headache is a primary concern given her current medications 1:

• Tirzepatide: This GLP-1/GIP dual agonist may cause headache as an adverse effect 2
• Minoxidil: Vasodilatory effects can trigger headaches, particularly with recent initiation or dose changes
• Timing of headache onset relative to medication initiation is crucial 3

Life-threatening secondary causes that must be ruled out include 1:

• Subarachnoid hemorrhage (thunderclap onset would be typical) 1
• Meningitis (fever and neck stiffness would be expected) 1
• Intracranial mass lesion 4, 5
• Temporal arteritis (though age <50 makes this less likely) 3

Essential Diagnostic Evaluation

History Elements to Clarify

Medication timing 3:

• When was tirzepatide initiated or dose adjusted?
• When was minoxidil started or changed?
• Any other recent medication changes?

Headache characteristics 1, 3:

• Exact onset pattern (sudden vs gradual over hours)
• Presence of aura or visual symptoms
• Associated nausea, vomiting, photophobia, or phonophobia
• Aggravation with physical activity or Valsalva maneuver 4
• Pattern throughout the day (constant vs intermittent)

Red flag symptoms 1, 4, 6:

• Fever or systemic symptoms
• Focal neurological deficits
• Altered mental status
• Visual changes
• Neck stiffness
• Recent head trauma
• Headache awakening from sleep 4

Physical Examination Priorities

Neurological examination must be thorough and normal findings would reduce concern for secondary causes 1:

• Mental status assessment
• Cranial nerve examination
• Motor and sensory function
• Reflexes and coordination
• Fundoscopic examination for papilledema 5

Vital signs and general examination 6:

• Blood pressure (minoxidil indication and hypertensive emergency)
• Temperature (infection)
• Temporal artery palpation (though age makes arteritis unlikely)

Neuroimaging Indications

Neuroimaging is indicated ONLY if red flags are present 1:

• Abnormal neurological examination findings 1
• Atypical features not meeting strict migraine criteria 1
• Sudden/severe onset suggesting subarachnoid hemorrhage 4, 6
• Progressive worsening pattern 6

If neuroimaging is needed 1:

• MRI is preferred over CT for higher resolution without radiation exposure 1
• CT is appropriate for acute trauma or suspected acute hemorrhage 4, 5
• Lumbar puncture follows normal CT if subarachnoid hemorrhage remains suspected 5

If neurological examination is normal and headache meets primary headache criteria, neuroimaging is usually not warranted 1

Most Likely Diagnoses in Order of Probability

1. Medication-induced headache from tirzepatide - Most common adverse effect of GLP-1/GIP agonists 2
2. Medication-induced headache from minoxidil - Vasodilatory mechanism
3. New-onset migraine without aura - Common in women of this age 1
4. Tension-type headache - Most prevalent primary headache disorder 1
5. Secondary headache requiring urgent evaluation - Must be excluded based on red flags 1, 6

Critical Pitfalls to Avoid

• Do not dismiss new-onset headache without thorough evaluation for secondary causes, particularly in a patient with no prior headache history 4, 3
• Do not order neuroimaging reflexively without clinical indication, as this exposes patients to unnecessary radiation and may reveal incidental findings causing alarm 1
• Do not overlook medication temporal relationship - carefully document when medications were started relative to headache onset 3
• Do not assume primary headache disorder until red flags have been systematically evaluated and excluded 1, 6