Can allergies cause loss of smell?

How allergies cause it

Your ability to smell comes from sensory cells, called olfactory sensory neurons, in a small patch of tissue high inside the nose.¹ Smells reach them through the nostrils and through a channel that connects the roof of the throat to the nose.¹ If that channel is blocked, as when your nose is stuffed up by a cold or flu, odors can’t reach the sensory cells.¹

Allergic rhinitis is an inflammatory disease of the lining of the nose, and reduced smell is a frequent symptom.² Researchers have proposed two ways it dulls smell: a blocked nose that keeps odors from reaching the smell tissue, and inflammation in the smell area itself.² A 2017 study suggests it may be a combination of both.² The same study notes that reduced smell is reported in 20 to 40% of people with allergic rhinitis, and cites earlier work that found smell problems mainly in people whose rhinitis lasts all year.²

Seasonal allergic rhinitis, or hay fever, is usually caused by pollen from trees, grass and weeds or by airborne mold spores.⁴ Year-round allergic rhinitis is generally caused by dust mites, pet hair or dander, cockroaches or mold.⁴

Without smell, foods tend to taste bland and have little or no flavor.¹ Smell is also a warning system that alerts you to danger signals such as a gas leak, spoiled food or a fire.¹

Allergies or something else?

Most people who develop a smell disorder have had a recent illness or injury.¹ Common causes include sinus and other upper respiratory infections, aging, smoking, growths in the nasal cavities, head injury, dental problems and exposure to certain chemicals, such as insecticides and solvents.¹

A new loss of taste or smell is one of the possible symptoms of COVID-19, which can also bring fever or chills.³ Hay fever does not cause a fever.⁴ Common hay fever symptoms include sneezing, congestion, itchy, watery eyes and an itchy nose, mouth and throat.⁴

When to see a doctor

If you have a smell disorder, talk with your doctor: any loss of smell can affect your quality of life, and it can also be a sign of more serious health problems.¹ A smell disorder can be an early sign of Parkinson’s disease, Alzheimer’s disease or multiple sclerosis.¹

The specialist for smell and taste disorders is an otolaryngologist, a doctor who focuses on diseases of the ear, nose, throat, head and neck, sometimes called an ENT.¹ If allergies seem to be behind it, ACAAI says consulting an allergist is the most effective way to diagnose allergic rhinitis.⁴