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Both allergies and migraines are an improper response by your body to a typically harmless trigger. Therefore, there is a strong temptation to assume the two are connected, which may or may not be the case.
Allergies can cause sinus headaches, which may be mistaken for migraines. Some people who think they are prone to sinus headaches are actually having migraines.
Some people may get both. The primary similarity is that both can be caused by increased inflammation and nasal congestion. Again, they are both improper responses by your body. This means that the same substance can cause both conditions.
A migraine headache is typically a sharp, intense headache on one side of the head, often accompanied by either visual disturbances (aura) or nausea and vomiting. On the other hand, a sinus headache is located across the front of the head and can cause dull pain.
Not all allergies cause headaches. However, three main allergy types can cause headaches or migraines. These include:
Allergic rhinitis (AR) is colloquially called "hay fever," even though it is rarely caused by hay. It is an inflammation of the inside of the nose caused by some kind of airborne allergen, typically pollen, mold, animal dander, or dust. Allergic rhinitis causes immediate symptoms: itching, problems with your sense of smell, sneezing, a runny nose, and watery eyes. Later symptoms do include headaches.
Allergic rhinitis is typically treated by avoiding the trigger, taking antihistamines as needed, and sometimes with corticosteroids taken through "allergy season."
Food is one of the most common triggers of migraines. Food allergies are an abnormal immune response to a food that can be mild or severe and can potentially cause anaphylaxis. The most common triggers are fish, shellfish, peanuts, and tree nuts. Typically, food allergies are treated by avoiding the offending food.
Sometimes, the primary symptom of a food allergy is a migraine, but these can be harder to detect as they take longer to present. While wine and aged cheese contain chemicals that can alter blood vessel constriction or dilation and can sometimes trigger headaches in people who don't normally get migraines, some people are triggered by healthy foods such as bananas or gluten. Scientists have been exploring the idea further to explain how completely healthy foods can be a trigger.
Doctors have traditionally thought of these as likely psychosomatic, but there's evidence that migraines may be triggered by improperly digested allergens passing through the intestinal lining. It hasn't been firmly tested yet, but the link is being investigated. In the meantime, identifying and avoiding food triggers can help you manage your symptoms.
Histamine is the substance that causes your body to overreact when you have an allergic reaction. This substance is also found in several foods.
In people with histamine intolerance, the consumption of histamine-rich foods can cause allergy-like symptoms and potentially headaches and migraines, although the primary symptoms are gastrointestinal.
Foods particularly high in histamine include:
Aged steak or game
Tinned or canned fish
Fish pates and spreads
Yogurts and similar fermented products
Dried fruits containing sulfites
Fermented or pickled products such as sauerkraut
Tomatoes and tomato-based products
Legumes and pulses
Fermented soy products, such as soy sauce or miso
Vinegar and dressings containing vinegar
Tea, both black and green
White, rose, and red wine
Champagne and prosecco
Beer and cider
This is a long list of foods, and the diet is not exactly sustainable. Typically, people with histamine intolerance work with a dietitian to identify specific foods that aggravate their symptoms.
So how, exactly, can these allergies cause migraines? There are several mechanisms that we suspect explain why people with these allergies may also get migraines:
Inflammation. This results in the activation of cells close to the brain's outer layer and trigeminal nerve, causing pain.
Nasal congestion, which irritates the trigeminal nerve in the nose. Taking decongestants to treat this symptom of allergic rhinitis can thus reduce the risk of migraine.
Sleep disturbances. Having allergy symptoms makes it harder to sleep, aggravating migraine symptoms.
Parasympathetic nerve activation. Allergy and asthma flare-ups cause dysregulation of the body's digestion response, resulting in dehydration, hunger, and fatigue, which can all cause migraines in some people.
Studies show that allergies can increase the frequency of migraine. One study¹ showed that migraine frequency in patients with allergic rhinitis was four times higher than in the control group. While people with AR are more likely to experience sinus headaches, high nitric oxide levels are produced in AR and have a vasodilator effect, which contributes to migraine.
Other studies showed that if you have hay fever and asthma, your attacks are likely to be 14 to 28% more frequent², and you are also 2.1 times more likely to develop chronic migraine. You're also more likely to have migraine in the first place if you have allergic rhinitis and more likely to have asthma if you have migraine.
This all indicates that there is likely a fairly strong connection, through inflammation, between allergies and migraine.
If allergies cause your migraines, this impacts your options for treating and controlling your migraines. Thankfully, the impact is mainly somewhat positive, as it gives you another angle of attack towards managing migraine episodes.
The easiest way to prevent a migraine triggered by allergies is to avoid the substance triggering your allergies. Close the windows during allergy season, walk down the other side of the block to avoid the tree that makes you sneeze, and keep your house clean to reduce pet dander and dust, etc.
If you have a food allergy, keep that food out of your diet. Avoidance is not always possible and sometimes undesirable.
For allergens that can't be avoided, allergy shots and other desensitization techniques can help mitigate the allergy, which will reduce the number of migraines triggered by it. Talk to your doctor about the best way to manage your allergies moving forward.
For some people, corticosteroid treatment can reduce migraines and allergy attacks. Be aware that corticosteroids have side effects, including potentially weakening your immune system.
If you know that hay fever triggers your migraines, you can take migraine medications before your headache starts, which can help reduce symptoms and get you back on your feet faster. You can also take meds if you have inadvertently consumed a food you are allergic to, such as if the food was poorly labeled at a party and you find out too late what was in it.
You should visit a doctor if you have any severe allergic reactions or want to get tested to confirm an allergy.
If you get a lot of allergy headaches or headaches after consuming certain foods, then you should talk to your doctor about the possibility that your headaches are, in fact, migraines.
If you have multiple food allergies, you may want to get a referral to a nutritionist to help you work around them, especially if it is a tricky allergy such as gluten. While you should not assume a migraine reaction to a food is actually an allergy, there is growing evidence that this might be the case. Unfortunately, such reactions can happen as many as 120 hours after consuming the food, making them hard to track.
Keeping a food diary helps.
Allergies and migraines are often linked. Having allergies, especially allergic rhinitis, increases your risk of getting migraines and the frequency of episodes if you do have them. This means that addressing your allergies through treatment or avoidance can potentially reduce your risk of migraine.
It's important to distinguish between migraines and sinus headaches, which can also be triggered by allergic rhinitis. Many people do experience both of these things. Your doctor can clarify the diagnosis for your specific condition.
Migraine, hay fever, asthma and allergies | American Migraine Foundation
Allergic rhinitis | Medline Plus
Food allergy | Medline Plus
Could a hidden allergy be causing your migraines? | SITN & Harvard University
A whole load of histamine: Exploring histamine intolerances | International Food Information Service