Can Allergy Cause Headache?

What is Allergy?

Allergy is abnormal reaction of a sensitive person to certain foreign substances (like food or drugs), heat, or physical contact that themselves are not harmful. It includes production of IgE antibodies and release of histamine what results in typical allergic symptoms: itch, hives, wet eyes, sneezing, runny nose, cough, or eczema, or, in severe cases, short breath or fainting.

Above is description of the IgE allergy.

Can Allergy Cause Headache?

Three types of headache are often mentioned as related to allergy:

• Sinus headache
• Migraine
• Cluster headache

Sinus Headache

In persons with dust allergy or hay fever, mucosa in sinuses (airy cavities in facial bones that are connected with nasal cavity) may get inflamed and swollen, thus obstructing sinus connections with nasal cavity. Continuing mucus secretion increases pressure in affected sinus thus causing pain in cheeks, teeth, forehead, top of the head, or elsewhere on the head.

It is a combination of facial pain, itchy wet eyes, runny nose, nose congestion, and sneezing that speaks for sinus headache (allergic sinusitis).

Diagnosisof sinusitis may be confirmed by X-ray, and diagnosis of allergy by blood tests (elevated eosinophils and IgE antibodies), and skin tests.

Prevention is in avoiding dust and pollens.

Treatmentis with antihistamines by mouth, intra-nasal corticosteroid sprays, decongestiants, or immunotherapy.

Migraine

Migraine is a headache, usually appearing on one side of the head, accompanied by nausea, and sensitivity to light. It is due to abnormal dilation of vessels in head muscles and subsequent irritation of nearby nerves, that may be triggered by:

• Specific light, sounds, or smells
• Nutrients: amino acids such as tyramine (in cheeses), dopamine, phenylethylamine or monosodium glutamate (common additive in oriental and packaged foods), phenylethylamine (in chocolate), alcohol, or aspartame (artificial sweetener)

Above stimuli don’t trigger production of IgE antibodies and histamine release, so they are non-allergic causes of migraine.

It was found out that people with food allergies or asthma often have migraines, but it is not clear how allergies and migraine are related. Antihistamines help to relieve symptoms in food allergies, but do not help in migraines that were supposedly caused by food.

Headache commonly appear in food intolerances like celiac disease, fructose malabsorption, or hereditary fructose intolerance (HFI), but these are not food allergies.

Cluster Headache

Cluster headache is a sudden strong pain appearing in, behind, or around the eye, sometimes spreading to the face or head, usually only on one side. It may last from 15 minutes to several hours. It often reappears in regular intervals, from here the term cluster (a group of resembling things, or events) and often at night, or in the morning, so it is also called alarm-clock headache. Headaches may appear over the course of several weeks then disappear for some weeks, and another cluster of headaches may start.

Cluster headaches often occur in spring and autumn, so they were related with allergies (3), but this was not confirmed (4). Cluster headaches are associated with abnormalities in a part of brain, called hypothalamus, and with abnormal vessel dilatation, like in migraine (5).

References:

1. Headaches caused by allergy (acaai.org)
2. Sinus headache (allergies.about.com)
3. Cluster headache (headaches.org)
4. Do allergies cause headache? (headaches.org)
5. Cluster headache mechanism (emedicinehealth.com)