Nausea, Headache & Fatigue: Possible Causes & When to See a Doctor

This symptom triad is nonspecific and spans benign to life-threatening etiologies. A structured approach:

Common Acute Causes

• Viral syndromes (influenza, COVID-19, gastroenteritis).
• Migraine (nausea, photophobia, throbbing headache).
• Dehydration / electrolyte imbalance.
• Medication side effects (antibiotics, opioids, chemotherapy).

Chronic / Systemic

• Endocrine: thyroid dysfunction, diabetes, adrenal insufficiency.
• Autoimmune: lupus, MS, celiac disease.
• Psychiatric: depression, anxiety, somatic symptom disorder.
• Sleep disorders: apnea, chronic insomnia.
• Nutritional: B12, iron, vitamin D deficiency.

Urgent Red Flags

• Thunderclap headache, focal neuro deficits, papilledema.
• Hematemesis, melena, severe abdominal pain.
• Fever + neck stiffness (meningitis).
• CO exposure, suicidal ideation.

Primary care evaluation with targeted labs/imaging guides diagnosis. Do not self-treat persistently.