People often mistake migraine for “just” a headache. However, the condition is a complex neurological disorder that causes persistent symptoms that occur before and after a headache.

As the phases that occur between migraine attacks do not involve a headache, they can help differentiate migraine from headaches. These phases include:

  • The prodrome phase: Also known as the preictal or premonitory phase, this phase occurs up to 48 hours before the onset of a headache. It may or may not include aura, which refers to visual disturbances such as flashing lights.
  • The postdrome phase: Also known as the postictal phase, this is the period right after a headache resolves. It typically lasts up to 24 hours after the headache is gone, and people sometimes refer to it as a “migraine hangover.”
  • The interictal phase: This is the period between migraine episodes and the specific pre- and post-headache phases.

The absence of a headache during these phases does not mean that people with migraine are symptom-free. Each phase is associated with a unique set of symptoms that can affect mental, emotional, and physical well-being.

This article investigates the interictal phase of migraine, looking at what symptoms may occur and how to find relief.

The interictal phase means the “between headaches” phase. Experts believe that the brain returns to its normal, resting state during this phase.

This does not happen immediately. Neurological changes characteristic of the headache phase of migraine may occur days before the actual onset of a headache.

There is also evidence that the brains of people with migraine are innately different from those in people without migraine.

The results from imaging studies suggest that the nervous system has structural and functional differences in people with chronic migraine. These differences may affect how the brain processes external stimuli and pain. In other words, the brain may be hardwired to be hypersensitive.

Structural and chemical changes in the brains of people with migraine mean that these individuals may not be completely symptom-free, even in the absence of a headache during the interictal phase.

Some research suggests that more than one-quarter of people with migraine experience symptoms during the interictal phase.

Symptoms that occur in the interictal phase may be similar to those that occur in the prodromal phase. They may include:

  • cognitive or mood changes, including anxiety
  • sensory symptoms, such as sensitivity to light or sound
  • gastrointestinal symptoms, such as nausea or food cravings
  • neck pain
  • fatigue

Studies also suggest that people with migraine have higher pain sensitivity during the interictal phase relative to people without migraine.

These symptoms can have a profound effect on the well-being of people with migraine in the absence of headaches. The cumulative burden of both a headache and lingering interictal symptoms can lead to:

  • lifestyle compromises
  • negative effects on education and career
  • emotional disconnect from family and friends

Even in the absence of symptoms, the interictal phase of migraine can be stressful. More than 10% of people with migraine report anxiety during the interictal phase related to the unpredictability of their next attack.

To help relieve this stress, the American Migraine Foundation recommends tracking interictal migraine symptoms in a migraine diary. This may help a person learn the warning signs of a migraine attack and predict when one is imminent.

One study found that by tracking their symptoms outside of headache windows, more than one-third of people with migraine were able to predict an oncoming migraine attack reliably.

This ability gives a person the opportunity to prepare for an attack and take early measures that could help prevent severe symptoms.

Although research is limited, some studies suggest that people can take steps that may help prevent or reduce symptoms during the interictal phase of migraine.

The first step is making sure that the overall symptoms of migraine are as well-controlled as possible. One study found that people who feel as though they are “rarely” or “never” in control of their headaches are more likely to experience interictal symptoms, including anxiety.

Research has also shown that people with chronic migraine have higher levels of calcitonin gene-related peptide (CGRP) in their blood during the interictal phase. CGRP is a molecule that experts believe plays a role in the development of migraine headaches. Many new migraine therapies target CGRP.

A 2021 study found that one of these agents — galcanezumab (Emgality) — may help reduce the severity of migraine symptoms during the interictal phase. More research is necessary to understand the effects of new therapies on interictal migraine symptoms.

Migraine is a complex neurological disorder that causes persistent symptoms even outside of migraine attacks. Functional differences in the brains and biology of people with migraine can lead to interictal symptoms that may disrupt daily living and have a significant impact on quality of life.

It is important for people living with migraine to understand their interictal symptoms and how these symptoms relate to potential patterns in their migraine episodes.

People who experience bothersome interictal symptoms should talk with a doctor to learn more about the steps they can take to gain better control of their migraine symptoms, including those that occur between headaches.