Can an Allergy Cause a Headache?
Allergies cause many symptoms depending on the part of the body where the inflammation is occurring. For example when the lining of the nose is irritated, there is sneezing and a runny nose. However, there are times when symptoms arise during an allergic episode that may not seem related to an allergy. Headaches are one such symptom.
An allergy is an abnormal immune reaction to certain substances, like food, drugs, dust, or other chemical or physical stimuli, that are otherwise harmless substances. It includes production of IgE antibodies and release of histamine which results in typical allergic symptoms: itching, hives, wet eyes, sneezing, runny nose, cough, eczema or, in severe cases, shortness of breathing or fainting.
Headaches with Allergies
It is not uncommon for headaches to occur with allergies particularly where the allergy involves the upper respiratory tract (nose, sinuses and throat). Three types of a headache are often mentioned in association with allergies. This includes:
- Sinus headaches
- Migraines
- Cluster headaches
Sometimes other conditions that accompany a headache may be mistaken for an allergy. This may be seen with CSF (cerebrospinal fluid) leads from the nose (rhinorrhea) which may also present with a headache. It is more likely to occur after a traumatic head injury or following head surgery. This fluid from the nose is not mucus and is not related to any allergic reaction. Therefore it is important to have what appears to be an allergy-related headache assessed by a medical professional.
Sinus Headaches
In people with dust allergies or hay fever, the mucosa of the nasal cavity and paranasal sinuses (airy cavities in facial bones that are connected with nasal cavity) may become inflamed. Swelling is a consequence of inflammation along with excessive mucus production. This causes obstruction and congestion of the sinuses.
Continuing mucus secretion increases pressure in the affected sinus eventually leading to pain in cheeks, teeth, forehead, top of the head or elsewhere in the head. It is a combination of facial pain, itchy wet eyes, runny nose, nose congestion, and sneezing that speaks for a sinus headache (allergic sinusitis).
Diagnosis of sinusitis may be confirmed by an X-ray. Diagnosis of an allergy is made by blood tests (elevated eosinophils and IgE antibodies) and skin tests. Prevention is by avoiding dust and pollens. Treatment is with antihistamines (oral), intra-nasal corticosteroid sprays, decongestiants or immunotherapy.
Migraine
Migraine is a type of headache, usually appearing on one side of the head, accompanied by nausea, and sensitivity to light. It is due to abnormal dilation (widening) of vessels in the head and subsequent irritation of nearby nerves. Migraines are often described as a very severe headache. It can be triggered by:
- Specific light, sounds, or smells.
- Psychological stress and emotional states.
- Nutrients: amino acids such as tyramine (in cheeses), dopamine, phenylethylamine or monosodium glutamate (common additive in oriental and packaged foods), phenylethylamine (in chocolate), or aspartame (artificial sweetener).
- Substances like alcohol, nicotine, caffeine and other stimulants or depressants.
- Unknown triggers.
The above stimuli do not trigger production of IgE antibodies and histamine release, so these are non-allergic causes of migraine. However, studies have shown that people with allergies are often at a greater risk of migraines although the exact link is unclear. Therefore a person may experience a migraine attack at the same time as an allergic episode Antihistamines help to relieve symptoms in allergies, but may be of little benefit in easing the symptoms of a migraine.
A headache commonly appears in food intolerances, like celiac disease, fructose malabsorption, or hereditary fructose intolerance (HFI) , but these are not food allergies. Instead it is due to the body’s inability to digest or absorb certain nutrients due to defects or disorders of the digestive tract and associated organs.
Cluster Headache
A cluster headache is a sudden strong pain appearing in, behind, or around the eye and sometimes spreading to the face or head. It is usually only on one side of the head and face. It may last from a few minutes to several hours. It tends to reappear at regular intervals, hence the term cluster, and often at night or in the morning. Therefore it is also called an ‘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 which is when seasonal allergies tend to worsen (3). However, there is no clear direct association between allergies and cluster headaches despite the seasonal synchronicity (4). Cluster headaches are associated with abnormalities in a part of the brain, called hypothalamus, and with abnormal vessel dilatation, like in migraine (5).
Other Headaches
Allergies are immune-mediated reactions. This means that the immune system causes the inflammation seen with an allergy. Although this inflammation is typically localized to one part of the body, it is possible that it may extend beyond this region. Antibodies that mediate immune responses, including allergies, can sometimes deposit on tissues elsewhere in the body. Inflammation may then ensue in these areas and pain is one feature of inflammation.
Therefore other types of headaches can also be associated with an allergy although there is no clearly defined mechanism to link the two events. Sometimes the association is vague. For example, people who are undergoing psychological stress may experience an exacerbation of allergies and at the same time experience headaches due to the stress.
Similarly dietary and lifestyle factors may link headaches and allergies. For example, a person who smokes tobacco may find an exacerbation of allergic symptoms in allergic rhinitis or allergic sinusitis. Tobacco consumption can also trigger a headache. Therefore the allergies may not be linked to the headache but both are caused by the same factor, namely the consumption of tobacco.
Related Articles:
- Headache Causes and Treatment
- Pain on the Back of the Head
- Types of Headache
- Headache and Constipation
- Non-Headache Head Pain
References:
- Headaches caused by allergy (acaai.org)
- Sinus headache (allergies.about.com)
- Cluster headache (webmd.com)
- Do allergies cause a headache? (acaai.org)
- A cluster headache mechanism (emedicinehealth.com)
