Can allergies cause sneezing?

How allergies cause it

With allergic rhinitis, or hay fever, a sneeze is the end of a chain reaction that starts in the immune system. Your immune system overreacts to an allergen by making antibodies called immunoglobulin E (IgE). These antibodies travel to cells that release histamine and other chemicals, which cause sneezing, stuffiness, a runny nose, itching and postnasal drip.¹

Nerves turn that reaction into a sneeze. Nerve cells called nociceptive neurons in the lining of the nose receive outside stimuli and trigger sneezing, a reflex mediated by nerve cells in the brainstem, and histamine makes sneezing worse.² These early symptoms begin almost immediately after exposure to the allergen, peak in a few minutes and subside within one to several hours.³

The allergens behind it fall into two groups. Seasonal allergic rhinitis is triggered by outdoor allergens such as pollen and mold spores. Some people have symptoms year-round due to indoor allergens from pets, mold, dust mites and cockroach residue, and some have a combination of both.¹

Pollen seasons and timing

Most of the pollen that causes allergic reactions comes from trees, grasses and weeds, which make small, light, dry pollen grains that travel by the wind. Flowering plants that spread their pollen by insects do not cause allergic rhinitis.⁵

Across the US, trees produce the most pollen from February through April. Grass pollen is most common from April through early June, and weed pollen appears in the late summer and fall.⁵ Outdoor mold adds to the mix: allergy symptoms from fungus spores are most common from July to the first hard frost.⁶

Allergies or something else?

Sneezing on its own does not settle the question, because it is usual with both a cold and an airborne allergy.⁸ Other clues help. An airborne allergy never causes a fever, while fever is rare with a cold, and if your eyes, nose or ears itch, that could also be an allergy.⁸

Timing is another clue. Hay fever symptoms can begin immediately after you are exposed to allergens like pollen or animal dander and continue as long as the exposure does. A cold most likely begins a day or two after exposure to the virus and can last a few days to a week.⁹ Allergy symptoms tend to stop when you are no longer exposed to the cause, and allergies are not contagious.⁸

Not every sneeze is an allergy or an infection. A sneeze can be brought on when the nerves in your eyes are exposed to bright light.¹⁰

When to see a doctor

If a cold seems to be the cause, seek medical care for trouble breathing or fast breathing, dehydration, a fever that lasts longer than 4 days, symptoms that last more than 10 days without getting better, symptoms such as fever or cough that improve and then return or worsen, or chronic medical conditions that get worse.¹¹

To find out what sets off your sneezing, an allergist will take a detailed medical history and review your symptoms to see whether your allergies are triggered by pollen, animal dander, mold, dust mites, cockroaches, weather changes or something else.¹⁰

Sneezing after eating a food you are allergic to needs more care. In a food allergy reaction, sneezing counts as a mild symptom, but a reaction that involves mild symptoms in more than one body area is also a severe reaction.¹² FARE’s steps for a severe reaction include calling 911 and going to the emergency room.¹²