Why Does My Migraine Pain Switch Sides? What We Know About Left Vs. Right-Sided Migraine

Oct 5

Medically reviewed by Dan Henry, M.D.

If your last migraine attack affected the left side of your head, why is today's on the right? And why does migraine seem to get to change the rules whenever it wants?

It can feel strange when migraine pain suddenly shows up somewhere different, especially if you're used to feeling it in the same place. But yes, migraine pain can switch sides from one attack to another.

Migraine is often described as causing one-sided, or unilateral, head pain. But unilateral doesn't mean it always has to be the same side. In a study of 1,283 people with migraine, pain was reported on the right side, left side, both sides, and on either side during different attacks.

So having one migraine attack on the left and another on the right isn't unusual.

Why does migraine pain switch sides?

The simple answer is: researchers don't completely know.

Migraine is a complex neurological disorder, and we're still learning why migraine pain shows up where it does. What we do know is that migraine doesn't always follow the same pattern. Your pain may be on the left during one attack, the right during another, or sometimes on both sides.

Side-switching isn't a new observation, either. A study published in Cephalalgia in 1989 found that when people’s pain was one-sided, it could shift between the right and left sides across attacks.

More recently, researchers have started asking an even more interesting question: Could the side of migraine pain tell us something about what's happening in the brain? We don't have the answers yet, but some early research suggests there may be differences between people who usually experience migraine pain on the left and those who usually experience it on the right.

Left-sided vs. right-sided migraine: is there a difference?

Maybe. This is where the research gets interesting.

A 2023 review looked at 26 studies comparing left and right-sided migraine and found some differences involving mental health, cognitive testing, the autonomic nervous system and even brain imaging.

We still don't know exactly what these differences mean, but researchers are finding enough to keep asking the question. So, what have they found about each side?

What does migraine pain on the left side of the head mean?

One of the most interesting findings about left-sided migraine has to do with how often and how severely people experience head pain.

A 2024 study found that people whose migraine pain was usually on the left had an average of 3.6 fewer headache-free days and 2.4 more severe headache days over four weeks compared to people whose pain was usually on the right. In other words, people with left-sided pain had more frequent and more severe head pain. The researchers described it as a “higher burden of headache frequency and severity.”

A 2023 review found that poorer quality of life was associated with left-sided migraine in some of the studies it reviewed. That's an especially interesting finding alongside the newer research showing a higher burden of frequent and severe head pain, although we don't yet know whether or how those findings are connected.

This 2023 review also found some other differences. In some studies, predominantly left-sided migraine was associated with:

anxiety
bipolar disorder
PTSD
lower sympathetic nervous system activity
higher parasympathetic nervous system activity

Those last two involve the autonomic nervous system, which helps control things your body does automatically, like heart rate, blood pressure, digestion and sweating.

And then there's one finding that sounds a little scary at first: those little white spots that sometimes show up on brain MRIs. A 2024 study looked at brain MRIs from 159 people whose migraine pain was typically on either the left or right side. People with typically left-sided pain had more white matter hyperintensities (WMHs) than those with typically right-sided pain. Interestingly, they had more WMHs on both sides of the brain, not just the left. The difference remained even after researchers accounted for age, high blood pressure, diabetes and smoking.

Before you start worrying about which side of your head hurts, there's some important context. Researchers still don't know what this finding means for someone's health. Having left-sided migraine pain does not mean something is wrong with the left side of your brain, and this study does not mean everyone with left-sided migraine needs an MRI.

What does migraine pain on the right side of the head mean?

Researchers have found some interesting differences with right-sided migraine, too.

Some studies found differences on certain cognitive tests, while others found differences in things like pupil size, skin temperature, blood pressure, blood flow and brain activity measured by EEG.

That's a pretty strange collection of findings. And right now, researchers don't know exactly what to make of them.

Most importantly, having migraine pain on the right side does not mean you have memory problems, abnormal blood pressure or something wrong with your brain.

These are patterns researchers found when comparing groups of people. They don't mean that someone with right-sided migraine should expect to have any of these differences. For now, these findings are giving researchers clues that left- and right-sided migraine may differ in ways we don't fully understand. But we're nowhere near being able to look at which side of someone's head hurts and predict what it means for their health.

Can migraine pain switch sides during the same attack?

Yes, a migraine attack can involve pain that changes sides. Some people with migraine describe pain that starts on one side of the head and then moves to the other side during the same attack. Others notice that the pain starts on one side and eventually spreads to both sides.

There isn't a lot of research looking specifically at migraine pain traveling all the way from left to right, or right to left, during a single attack. But researchers have shown that migraine pain can change location as an attack progresses.

Does the side of migraine pain tell you how serious it is?

Having migraine pain on the right side of your head isn't automatically more concerning than having it on the left. And the research we just discussed doesn't mean one side is the "bad" side.

What's more useful is paying attention to your usual pattern.

If your migraine attacks have alternated sides for years, that's very different from suddenly developing a new type of head pain that you've never experienced before.

And there's another pattern worth knowing about: pain that never switches sides.

What if my migraine pain is always on the same side?

Some people with migraine notice that their pain almost always shows up on the same side of their head. And yes, that can still be migraine.

There's actually a medical term for head pain that consistently stays on one side: side-locked headache. Migraine can be side-locked, but it isn't the only type of headache disorder that can cause pain that stays on one side.

A review published in The Journal of Headache and Pain found that side-locked pain can occur with migraine as well as other headache disorders, including cluster headache, hemicrania continua and paroxysmal hemicrania. There are also some secondary causes of headache that can cause pain on only one side.

So if your pain is always on the same side, especially if this is a new pattern or you've never talked to your healthcare provider about it, it's worth mentioning. It doesn't automatically mean something is wrong. It simply gives your healthcare provider another clue when figuring out what's causing your head pain.

Why does my neck hurt on the same side as my migraine pain?

If your migraine pain is on the left, you might notice that your neck hurts on the left, too. That's very common.

In one study of 144 people with migraine, 75% reported neck pain with their migraine attacks. And when that neck pain was only on one side, 98% said it was on the same side as their head pain.

That's probably not surprising when you consider how closely neck pain and migraine are connected. A 2025 review found that neck pain is very common during migraine and, for many people, appears to be part of the migraine attack itself.

The bottom line on migraine pain switching sides

For most people, the side of the pain is just one piece of a much bigger migraine picture.

Migraine pain can occur on the left, the right, both sides, or switch sides between attacks. Researchers are finding some fascinating differences between people whose migraine pain usually occurs on the left and those whose pain usually occurs on the right. We don't yet know what those differences mean for any one person, but they're another reminder of just how much we're still learning about migraine.

The biggest takeaway? Know what's normal for your migraine. If your pain has always switched sides, that can simply be part of your usual migraine pattern. But if something about your head pain suddenly feels new or significantly different, that's worth talking to your healthcare provider about.