Do you find that your migraine attacks seem to happen when your allergy symptoms flare up? As one MyMigraineTeam member asked, “I get a lot at the beginning of spring. With that comes migraine attacks. Why is this?”

You’re not imagining the connection between chronic migraine and allergies. Many people have more frequent migraine attacks as the seasons change due to seasonal allergies. But the allergen itself doesn’t trigger the attack — your body’s reaction to the allergen does.

Let’s take a deeper look into the link between migraine and allergies. You’ll also discover how an allergic reaction can trigger or worsen a migraine attack.

The Role of Histamine

Health experts continue to study how migraine and allergies are connected. They believe histamine may be a central factor in the connection.

Histamine is a chemical your immune system makes to help your cells communicate. Research suggests that people with migraine have more histamine in their blood.

How Histamine Works in Allergies

When your immune system detects proteins from an allergen inside your body, it releases histamine. This leads to an inflammatory reaction. That reaction is why you have allergy symptoms like itchy skin and extra mucus production.

The Connection Between Histamine and Migraine

Health experts think histamine plays a role in migraine, too, but they don’t fully understand how. Some studies have shown a possible link between migraine and histamine intolerance, but more research is needed. Histamine intolerance occurs when there’s too much histamine in your body that you can’t break down.

Histamine may play a role in migraine attacks because it:

• Widens your blood vessels
• Causes inflammation in the nervous system
• Increases nitric oxide, a chemical that likely plays a role in migraine attacks

Histamine may also contribute to migraine attacks because it’s involved in hypothalamus activity. The hypothalamus is a gland in your brain that regulates your body’s hormones and nervous system.

Within the hypothalamus, histamine helps control your sleep-wake cycle. Hypothalamic activity may be linked to migraine attacks and more severe migraine symptoms.

Overlap Between Migraine and Allergies

People with allergic rhinitis (sinus allergies) have a higher risk of migraine. Some research suggests that roughly half of people with allergic rhinitis also have migraine. Those with allergic rhinitis also have more frequent migraine attacks than those without allergies.

How Allergy Severity Affects Migraine Attacks

Some research suggests that — at least for people under the age of 45 — increased atopic sensitization (when your immune system is prone to react to particular allergens) may be linked to more frequent migraine attacks. People with milder allergies tend to have less disabling migraine attacks that happen less often.

How Migraine Can Be Mistaken for Allergies

It’s easy to mistake a migraine attack for a sinus headache, a type of headache triggered by allergies — and vice versa. As one MyMigraineTeam member shared, “When the pollen is high, my head hurts and I can’t figure out if it’s migraine or sinus.”

A sinus headache can occur when swelling in the sinus cavities causes pressure to build up. This swelling leads to sinus pain in the head and face. That pain is often accompanied by sinus symptoms that may include nasal congestion, sneezing, or postnasal drip.

Research suggests that 50 percent or more of self-reported sinus headaches may not be sinus headaches at all. Instead, they meet the criteria for migraine attacks. Adding to the diagnostic challenge, some migraine attacks also involve a runny nose or other mild sinus symptoms.

How Allergies May Trigger or Worsen Migraine Attacks

Several ways that allergies affect your body may explain how they can trigger or worsen migraine attacks. The chain of events begins with the release of histamine. It then continues with allergy symptoms such as sinus congestion.

Nasal Congestion

Nasal congestion in allergic rhinitis may trigger or contribute to migraine headaches. Increased nasal congestion and sinus pressure can irritate the trigeminal nerve. This nerve controls sensory information inside your brain. Any irritation to the nerve can trigger a migraine attack.

Disrupted Sleep

It’s not always easy to get a good night’s sleep when you have allergic rhinitis, itching, or other allergy symptoms. Any sleep disturbance can increase the risk of a migraine attack. Disrupted sleep can also lead to more severe migraine headaches.

Inflammation

Inflammation caused by allergies can also irritate the trigeminal nerve to trigger a migraine attack. Inflammation in general is a likely underlying cause of migraine attacks and can be directly caused by allergies.

Shared Environmental Triggers

Some people’s allergies flare up because of environmental triggers, like weather changes, emotional stress, or certain foods. For some, these are also migraine triggers.

Allergies and migraine attacks can have multiple overlapping triggers. Your doctor might encourage you to keep a journal documenting your allergy symptoms and migraine attacks. The journal may help you identify shared triggers that affect you.

Managing Allergies To Reduce Migraine Attacks

For some people, managing allergies may reduce the frequency and severity of migraine attacks. Allergy medications like antihistamines or other allergy treatments can help control the inflammation and nasal congestion linked with attacks. You’ll also probably get more consistent sleep once your allergies are under control.

Avoiding Allergens

Avoiding your allergens when possible can help prevent or reduce the frequency of allergy symptoms. But some allergens, like pollen, can be hard to avoid. Your doctor may recommend allergy medications to help avoid allergic reactions, too.

Preparing Your Home

If you have seasonal allergies or hay fever, preparing your home for the seasonal change can help reduce exposure to allergy-causing pollen. Some home preparation can also reduce your exposure to dust mites, animal dander, or other in-home allergens.

Try these tips to reduce the risk of allergy symptoms:

• Wear a mask while dusting or vacuuming.
• Install an air purifier.
• Change your air purifier’s filter every three months.
• Wash your bedding frequently.
• Deep clean your rugs and furniture frequently.
• Use a dehumidifier to lower the risk of mold in the home.
• Monitor your local pollen counts to know when they’re high and likely to cause allergy symptoms.
• Keep your windows closed during allergy season.

Immunotherapy

Immunotherapy provides a way to build your body’s tolerance to allergens so they’re less likely to cause symptoms. Allergy shots, the most common type of immunotherapy, involve injecting increasing amounts of the allergen to change the way your immune system responds to it.

Research suggests that people under age 45 with allergies and migraine who have had immunotherapy may get less frequent and less severe migraine symptoms. Ask your doctor whether immunotherapy may help reduce the frequency of migraine attacks that are linked to allergies.

Speak With Your Doctor

If you have frequent migraine attacks, with or without an allergy diagnosis, tell your doctor. Your neurologist might recommend allergy testing to identify triggers that may contribute to your migraine attacks.

Allergy testing can also help an allergist plan your allergy treatment effectively. The right allergy treatment plan may help reduce migraine frequency and severity.

Join the Conversation

On MyMigraineTeam, people share their experiences with migraine, get advice, and find support from others who understand.

Have you ever experienced a migraine attack triggered by allergies? Let others know in the comments below.

Are your headaches a symptom of migraine? Get a quick assessment.