Can allergies cause headaches?

How allergies cause it

ACAAI links two kinds of headache to allergies: sinus headaches and migraines.¹

A sinus headache starts with swelling. The sinus cavities are hollow air spaces in the skull with openings into the nose, and allergies can cause swelling that may block those openings and let pressure build up.¹ The pain is usually felt over the sinus area. Your cheeks may be tender to the touch, and the pain may extend to your jaw and teeth.¹ It can be dull to intense, often begins in the morning, and becomes less intense after you move from lying flat to sitting or standing upright.¹ Common seasonal and year-round allergens like pollen, mold and pet dander can make the immune system react with a sinus headache even when you have no other allergy symptoms.¹

A sinus infection is a separate link. CDC lists seasonal allergies among the risk factors for a sinus infection, and headache and facial pain or pressure among its symptoms.²

A migraine is different. It is usually a throbbing pain on one side of the head. Light may make it worse, and you might also have nausea.¹ Migraines can be caused by many factors, including genetics, and environmental allergies and food intolerances have been linked to them.¹ Irritants like smoke or strong scents can also trigger a migraine.¹

Allergies or something else?

Pain behind the cheeks and forehead is easy to blame on the sinuses, but the sinuses are often not the cause. A 2021 systematic review found that the majority of studies identify migraine as the cause in people who report a “sinus headache.”³ Migraine and tension-type headache were the most common causes in people who saw a doctor for it.³

Cluster headaches are sometimes mistakenly linked to allergies, but they are not an allergic condition.¹

Many other things cause headaches. ACAAI’s list of causes to ask about when allergies are ruled out includes a cold or flu, dehydration, emotional or physical stress, changes in sleeping or eating, alcohol, teeth-grinding at night and concussion. It also names glaucoma, stroke, blood clots, a brain tumor and carbon monoxide poisoning.¹

When to see a doctor

NINDS advises immediately calling or seeing a physician for a very sudden, severe headache that may come with a stiff neck; a severe headache with fever, nausea or vomiting that is not related to another illness; or a sudden “worst” headache, often with confusion, weakness, double vision or loss of consciousness.⁴ The same applies to a headache after a head injury, a headache with loss of sensation or weakness in any part of the body, which could be a sign of a stroke, and a headache with convulsions or with shortness of breath.⁴ NINDS also lists a headache that worsens over days or weeks or has changed in pattern or behavior, a new onset of two or more headaches a week, a persistent headache in someone who has been headache-free (particularly someone over age 50), new headaches in someone with a history of cancer, immune suppression or HIV/AIDS, and a headache that comes on when upright and goes away when lying flat.⁴

With a sinus infection, CDC advises seeing a healthcare provider for severe symptoms such as a severe headache or facial pain, symptoms that get worse after improving, symptoms lasting more than 10 days without getting better, a fever longer than 3 to 4 days, or multiple sinus infections in the past year.²

If you have sinus headaches or migraines, a board-certified allergist can help you find out whether allergies are behind them.¹