It may signal serious illness

Most of us take our sense of smell for granted. But for the surprising number of people for whom this vital sense is dulled, the consequences can be more serious than you might imagine. Smell disorders affect half of people age 65 and older, with more cases occurring in men than in women.

Danger: When a person’s sense of smell is not functioning properly, it can lead to related health problems, such as loss of appetite, high blood pressure (due to the use of too much salt) and/or weight gain (due to excessive sugar intake). Gas leaks and fires also may endanger people with an impaired sense of smell.

Why your sense of smell is so important…


We all know that allergies, colds and nasal congestion interfere with our sense of smell. These conditions cause nasal obstruction that prevents odors from reaching olfactory receptors (sensory nerve cells) in the nasal lining.

A blunted sense of smell is common with this type of obstruction, but the sense usually returns within a few days or weeks. When the damage is severe or repeated enough times, the cells can be permanently disabled. The persistent state of inflammation that occurs with chronic sinusitis also can permanently impair olfactory cells.

Other causes of impaired smell…

Aging. As we grow older, the nerves involved in smell weaken, and membranes lining the nose become thin and dry.

Head injury. When the brain is jarred within the skull, olfactory nerve fibers may be damaged. Smell loss from traumatic head injury is usually more severe than that caused by infection. Even a relatively mild impact — not enough to cause a concussion — can lead to permanent loss of smell.

Medications. Heart drugs, such as the cholesterol-lowering medication atorvastatin (Lipitor), the calcium channel blocker verapamil (Covera) and the blood pressure–lowering agent doxazosin (Cardura), are among the medications most likely to impair one’s sense of smell or taste. Other blood pressure drugs, such as angiotensin-converting enzyme (ACE) inhibitors, including enalapril (Vasotec) and enalapril and hydrochlorothiazide (Vaseretic), also may lead to loss of smell or taste.

Environmental toxins. The precise effect of environmental toxins, such as pesticides, is uncertain, but they can clearly damage one’s sense of smell. In a 2009 study published in Experimental and Toxicologic Pathology, a group of residents of Mexico City — notorious for its air pollution — scored significantly lower on a smell identification test than residents of cleaner environments. Upon closer examination, signs of damage in the nasal lining and in the olfactory bulb (which processes smell signals) within the brain were found in the study subjects.


The olfactory system is highly vulnerable to brain disorders, and a noticeable decline in the sense of smell occurs in 85% to 90% of people in the early stages of Alzheimer’s and Parkinson’s disease. In fact, the American Academy of Neurology recommends the use of smell tests as an aid to help diagnose Parkinson’s disease.

There’s even increasing evidence that smell loss begins in the so-called “preclinical” period — preceding classic symptoms of Alzheimer’s (such as memory loss) and Parkinson’s (such as movement problems) by several years.

Low thyroid function (hypothyroidism) also can lead to loss of smell. Distorted or phantom smells (smelling an odor, such as a chemical or floral scent, that is not present) may point to epilepsy or a brain tumor or Alzheimer’s disease.


If you think that your ability to distinguish odors has gotten significantly worse, it may be worth having it tested by your doctor. Few physicians routinely provide smell testing, so you will probably need to ask for it.

Or you can take a self-administered smell test that was developed by myself and other researchers at the University of Pennsylvania. Known as the Smell Identification Test (SIT), it is a scratch-and-sniff–type test and is available from the manufacturer (800-547-8838,

Cost: $27 for the test and $3.50 for the scoring key. For the most accurate results, take the test in your doctor’s office and ask him/her to help you interpret the results.


Once seriously damaged, one’s sense of smell may improve but is unlikely to recover fully.

Smell loss due to nasal inflammation can be treated with steroid drugs, such as prednisolone (Prelone), in nasal spray or pill form. But long-term use of the pill form of prednisolone and overuse of the nasal spray are not recommended because damage to the liver, kidney or bones may result.

Meanwhile, research using stem cells is under way at several universities to explore whether damaged olfactory receptor cells could be replaced with healthy cells in the future.

Prevention is the best defense against loss of smell. Exposure to tobacco smoke — both through smoking and exposure to secondhand smoke — dulls the sense of smell but is generally less devastating than one might expect. If you smoke, quitting cigarettes generally will restore any loss of your sense of smell — but that recovery can take years.

Other prevention strategies…

Avoid infection. While occasional colds and the flu are inescapable, good hygiene practices (including frequent hand-washing) will make them less frequent.

Protect your head. Wear seat belts in the car and a helmet when riding a bike, roller-blading, skiing or participating in any sport or activity that could lead to a head injury. Don’t participate in sports, such as boxing or football, that may involve frequent blows to the head.

Breathe clean. Take precautions around toxic chemicals at work, and herbicides and pesticides at home. Use these substances only in well-ventilated areas and wear a mask. Instead of using toxic household cleansers, detergents and other such products, choose safer alternatives, such as vinegar and baking soda.