Headaches are common during infections, ranging from mild viral illnesses to more serious conditions. They often signal the body’s immune response to an invading pathogen. While many infection-related headaches are benign and resolve with the underlying illness, understanding their causes and recognizing warning signs helps determine when medical attention is necessary.
How Infections Trigger Headaches
The body’s reaction to an infection often triggers headaches through several physiological mechanisms. A primary mechanism involves systemic inflammation, where the immune system releases signaling molecules called cytokines. These cytokines can sensitize pain receptors and contribute to widespread inflammation, including around the brain, leading to headache pain.
Fever, a common response to infection, can also induce headaches. Elevated body temperature can cause blood vessels in the brain to dilate, increasing pressure inside the head. Dehydration, often accompanying fever, further contributes to headaches by affecting brain volume and pressure. In some instances, particularly with infections affecting the central nervous system, increased intracranial pressure or direct irritation of pain-sensitive structures, such as the meninges, can cause severe headaches.
Common Infections Linked to Headaches
Headaches are a frequent symptom across common infections. Viral infections like the common cold, influenza, and COVID-19 often present with headaches. Influenza-related headaches can be an early sign of the illness. COVID-19 headaches can resemble tension-type headaches or migraines, often bilateral and moderate to severe. Mononucleosis, another viral infection, also commonly includes headaches as a symptom.
Bacterial infections can also cause headaches, sometimes with more severe implications. Sinusitis, an inflammation of the sinus cavities, leads to headaches due to pressure buildup from mucus and inflammation. This pain is typically felt behind the eyes, in the cheekbones, or across the forehead, often worsening with sudden head movements or bending over. Strep throat, a bacterial infection, often includes headaches among its systemic symptoms. Meningitis, an infection of the membranes surrounding the brain and spinal cord, commonly causes severe headaches.
When to Seek Medical Care
While many infection-related headaches are not serious, certain “red flag” symptoms warrant immediate medical evaluation. A sudden, severe headache, often described as the “worst headache of your life” (thunderclap headache), can signal a serious condition like a brain bleed. Headaches accompanied by a stiff neck and high fever are concerning for meningitis, an infection that requires prompt treatment.
Other warning signs include confusion, altered mental status, or new neurological deficits such as weakness, numbness, or difficulty speaking. Vision changes, such as blurred or double vision, or a rash that does not fade when pressed, also indicate a need for urgent medical attention. Persistent vomiting or a headache that progressively worsens despite other infection symptoms improving should also prompt a medical consultation. Individuals who are immunocompromised or over 50 years old should seek prompt evaluation for new or changing headaches.