A migraine is a neurological event characterized by intense head pain and symptoms like nausea and sensitivity to light and sound. In contrast, a fever is an elevation in the body’s core temperature, typically a regulated immune response to systemic inflammation or infection. While many people report feeling warm or chilled during an attack, a migraine itself does not generally cause a true fever. If a genuine fever occurs alongside a severe headache, it suggests a separate medical issue is likely present.
Migraine and Temperature Regulation
The process of a migraine attack involves a complex neurovascular cascade, which is fundamentally different from the systemic immune response that causes a fever. This neurological event originates from the activation of the trigeminovascular system, a network of nerves that relay pain signals from the blood vessels surrounding the brain. Activation of this system leads to the release of inflammatory neuropeptides, such as calcitonin gene-related peptide (CGRP), into the meninges.
This release of neuropeptides causes localized neurogenic inflammation in the protective layers of the brain. This is a regional response, not a widespread infection or inflammatory process affecting the entire body. A true fever requires pyrogens, which are substances that travel through the bloodstream and signal the hypothalamus—the brain’s temperature control center—to raise the core body temperature set point.
Because the migraine cascade is localized and neurological, it does not typically trigger the hypothalamus to initiate a systemic, regulated core temperature increase. Therefore, despite the intense pain and discomfort, the body’s central thermostat remains unaffected, and a true fever does not develop.
Understanding Autonomic Symptoms
Many individuals report feeling “feverish,” flushed, or having the chills, which explains the common confusion about a migraine causing a fever. These sensations are peripheral manifestations of temporary dysfunction in the autonomic nervous system (ANS), which regulates involuntary body functions.
The ANS is divided into the sympathetic and parasympathetic systems, and migraines can disrupt this balance. This imbalance leads to symptoms like flushing (vasodilation) or pallor (cutaneous vasoconstriction), which are rapid changes in blood flow near the skin’s surface. These vascular shifts create subjective sensations of being hot or cold without altering the body’s core temperature.
Other symptoms of ANS involvement include excessive sweating (diaphoresis) or goosebumps (piloerection), which can mimic the feeling of a fever breaking or having the chills. The presence of cranial autonomic symptoms, such as tearing, nasal congestion, and eyelid drooping, further indicates the involvement of this system during an attack. These are temporary, peripheral symptoms of the neurological event.
When Fever and Headache Signal an Emergency
While a migraine does not cause a fever, the co-occurrence of a severe headache and a true fever is a sign that a serious secondary condition may be present. This combination is considered a medical red flag that requires immediate professional evaluation.
A severe headache alongside a fever may indicate a systemic infection, such as the flu or COVID-19, that has triggered a migraine in a susceptible individual. However, the combination can also signal a dangerous neuroinfection affecting the nervous system.
Conditions like meningitis, an inflammation of the membranes surrounding the brain and spinal cord, or encephalitis, an inflammation of the brain itself, commonly present with both a severe headache and a fever. Other concerning symptoms that mandate immediate medical attention include:
- A stiff neck
- Confusion or altered mental status
- Seizures or neurological deficits
- A headache described as the “worst of your life” that starts suddenly (thunderclap headache)
Seeking prompt care is necessary to rule out life-threatening causes of a simultaneous headache and fever.