What causes a headache on the right side of the head?

Right-Sided Headache: Causes and Clinical Approach

Right-sided headache can result from both benign primary headache disorders and life-threatening secondary causes that require immediate recognition and intervention.

Life-Threatening Causes to Exclude First

The following conditions must be ruled out urgently when evaluating right-sided headache:

Subarachnoid Hemorrhage (SAH)

• Presents with sudden, severe "thunderclap" headache that may be unilateral, reaching maximum intensity within seconds to minutes 1
• Non-contrast CT of the head is the initial imaging modality of choice due to superior sensitivity for detecting acute blood products 1
• If CT is negative but clinical suspicion remains high, lumbar puncture is mandatory to exclude SAH 2
• SAH from ruptured aneurysm accounts for 70% of all nontraumatic subarachnoid hemorrhages, with 25% mortality after presentation 1

Cerebral Venous Thrombosis (CVT)

• Headache is present in nearly 90% of CVT cases and is typically diffuse but can be unilateral 1
• Consider CVT when headache is accompanied by focal neurological deficits, seizures (occurring in 40% of cases), or papilledema 1
• MRI with MR venography (MRV) is the study of choice for diagnosis 1
• Median delay from symptom onset to diagnosis is 7 days, making this a commonly missed diagnosis 1
• Bilateral thalamic involvement may occur with deep venous system thrombosis, causing altered consciousness without focal findings 1

Brain Tumor or Space-Occupying Lesion

• Headache that awakens the patient from sleep, worsens with Valsalva maneuver, coughing, sneezing, or exercise suggests increased intracranial pressure 2, 3
• 94% of children with brain tumors have abnormal neurological findings at diagnosis, and 60% have papilledema 1
• MRI with and without contrast is the imaging modality of choice when tumor is suspected 1, 2

Cervical Artery Dissection

• Can present with unilateral headache and neck pain, potentially progressing to stroke 4
• Requires urgent vascular imaging with CTA or MRA 4

Meningitis/Encephalitis

• Headache accompanied by fever, neck stiffness, and altered mental status requires immediate evaluation 2, 4
• Lumbar puncture is diagnostic after neuroimaging excludes mass effect 1

Red Flags Requiring Urgent Evaluation

Any of the following warrant immediate neuroimaging and further workup 2, 3:

• Age ≥50 years with new-onset headache
• Recent head or neck trauma
• New, worse, worsening, or abrupt onset headache
• Headache brought on by Valsalva maneuver, cough, or exertion
• Focal neurological symptoms or signs on examination
• Altered consciousness, memory, or personality changes
• Neck stiffness or limited neck flexion
• Witnessed loss of consciousness
• Progressive worsening over time
• Systemic signs (fever, weight loss) or symptoms suggesting systemic illness
• Immunocompromised state or cancer history

Primary Headache Disorders Causing Right-Sided Pain

Migraine

• Migraine attacks last 4-72 hours in adults with pulsating quality, moderate to severe intensity, and associated symptoms including nausea, photophobia, or phonophobia 1, 5
• Unilateral location is characteristic, though side may vary between attacks 1
• Research suggests left- versus right-sided migraine may have distinct characteristics, with right-sided migraine associated with poorer cognitive performance and specific autonomic changes 6
• Migraine with aura involves fully reversible visual, sensory, or speech symptoms developing gradually over 5 minutes, lasting 5-60 minutes, followed by headache 1
• Common pitfall: Approximately 62% of pediatric migraineurs have cranial autonomic symptoms (rhinorrhea, nasal congestion) that can be misdiagnosed as "sinus headache" 1

Cluster Headache

• Severe unilateral orbital, supraorbital, or temporal pain lasting 15-180 minutes 5
• Accompanied by ipsilateral autonomic symptoms: tearing, nasal congestion, eyelid edema, facial sweating 5
• Attacks occur in clusters with circadian periodicity

Primary Stabbing Headache

• Ultra-brief duration lasting literally 1-3 seconds with sharp, "ice pick" quality 5
• Can occur anywhere on the head, commonly in areas where migraine typically occurs 5
• No associated symptoms like nausea, photophobia, or autonomic features 5
• Benign and self-limited; indomethacin highly effective if attacks become frequent 5

Secondary Causes of Right-Sided Headache

Sinusitis

• Maxillary sinusitis can cause both headache and altered taste, particularly following dental procedures involving upper premolars or molars 2
• However, "sinus headache" is commonly a misdiagnosis of migraine with cranial autonomic symptoms 1
• CT may be performed if complicated sinusitis with intracranial spread is suspected 1

Giant Cell Arteritis (Temporal Arteritis)

• Must be considered in patients over 50 years with new-onset headache, scalp tenderness, and jaw claudication 2
• Delay in treatment can lead to permanent vision loss 2
• ESR/CRP should be obtained urgently 2

Intracranial Hypotension

• Can present with orthostatic headache (worse when upright, better when lying down) 1
• MRI shows smooth, diffuse dural and leptomeningeal enhancement 1
• May precipitate cerebral venous thrombosis as a life-threatening complication 1

Diagnostic Approach Algorithm

Step 1: Identify Red Flags

• Perform focused history targeting red flag features listed above 2, 3
• Complete neurological examination including cranial nerves, motor/sensory function, cerebellar testing, and fundoscopic examination 1, 2
• Vital signs assessment including blood pressure and temperature 2

Step 2: Determine Imaging Urgency

Immediate imaging indicated for:

• Thunderclap headache: Non-contrast CT head if presenting <6 hours from onset 1, 2
• Any red flag features: MRI brain with and without contrast preferred for subacute presentations 1, 2
• Suspected CVT: MRI with MRV 1
• Suspected vascular dissection: CTA or MRA of head and neck 4

No imaging required for:

• Typical primary headache pattern with normal neurological examination and no red flags 1, 7
• Neuroimaging has limited role in patients with primary headaches, with yield <1% for clinically relevant findings 1

Step 3: Additional Testing Based on Clinical Suspicion

• Lumbar puncture if CT negative but SAH still suspected, or if meningitis/encephalitis considered 1, 2
• ESR/CRP if temporal arteritis suspected in patients ≥50 years 2
• D-dimer may have role in excluding CVT when combined with pretest probability assessment 1

Critical Pitfalls to Avoid

• Do not dismiss unilateral headache as benign without thorough neurological examination 3, 4
• Do not attribute headache with rhinorrhea to sinusitis without considering migraine with cranial autonomic symptoms 1
• Do not miss temporal arteritis in elderly patients—delay causes irreversible vision loss 2
• Do not rely solely on imaging without considering complete clinical picture including temporal relationship and associated symptoms 2
• Do not assume bilateral involvement is required for serious pathology—CVT and other conditions frequently present with unilateral symptoms 1, 6
• Do not overlook CVT in patients with headache and seizures—this combination occurs in 40% of CVT cases 1
• Do not perform routine neuroimaging in children with typical primary headache patterns and normal examinations—yield is <1% 1