Smell and Taste Disorders

Problems with Smell: Frequently Asked Questions

Our sense of smell is the ability to detect odors in our environment, like the fragrance of flowers or the smell of baking bread. Smell is also the ability to detect food odors released in our mouths when we eat, which then flow from the throat to the nose. Smell is part of our chemical sensing system, or the "chemosenses."

Smell is important because it lets us fully enjoy scents and fragrances, and contributes greatly to our enjoyment of food and beverages. But, even more important, smell can be a warning sign that something is wrong in our environment. Smell helps us to know when food is spoiled or if there is a gas leak.

Yes. Many people mistakenly think they have a problem with taste, when what they are really experiencing is a problem with smell. It is common for people who lose their sense of smell to think that food has lost its taste. This is usually not the case. The food has lost its aroma, but tastes, such as sweet, salty, sour, and bitter, remain.

Roughly 200,000 people each year visit a doctor for either a smell or taste problem. Thirty percent of older Americans between the ages of 70 and 80 have a problem with their sense of smell. Two out of three people over the age of 80 have a problem with their sense of smell, with men affected more often than women.

Some studies estimate that more than two million people in the United States have problems with smell and taste. The number may be much higher, because many cases are not reported.

Older people who have lost their sense of smell may eat too much or eat too little. In severe cases, loss of smell can lead to depression. Although problems with smell are rarely life-threatening, loss of smell can be dangerous. Identifying smells is your brain's way of providing you with information about your environment and keeping you safe.

Normal smell occurs when the odors around us release microscopic molecules into the environment that stimulate small nerve cells, called olfactory cells, located high up in the nose. Once the cells detect the molecules, they send messages to our brains, where we identify the smell.

There are several types of smell disorders depending on how the sense of smell is affected. If you have a smell disorder, you may experience a decrease in your ability to smell or changes in the way you perceive odors. Or you may not be able to detect any odor at all.

Sometimes, familiar odors may become distorted, or an odor that usually smells pleasant instead smells foul. Some people with smell disorders perceive a phantom smell or a smell that isn't there at all.

Most people who have a problem with smell have recently had an illness or injury. The most common causes are upper respiratory infections, such as the common cold, and chronic sinus or nasal disease. Other common causes are head injuries and exposure to toxic chemicals.

Nasal polyps can block the ability of aromas to reach nerve cells. People with head and neck cancers who receive radiation treatment to the nasal area can also experience problems with smell.

Problems with smell that occur with aging are not preventable. Loss of smell caused by respiratory infections and colds can be prevented by washing your hands frequently, especially during the winter months.

If your smell disorder is caused by allergies, you should avoid allergens, like ragweed, grasses, and pet dander. Quitting smoking also may improve smell and prevent loss of smell.

In rare cases, certain medicines may cause a change in your ability to smell. Antibiotics and blood pressure pills are among the most common medications that cause a problem with smell. If you are taking these medications and notice a change in your sense of smell, talk to your doctor. You may be able to adjust or change your medicine to one that will not cause a problem with smell.

Sometimes it is difficult to determine if the problem with smell is caused by medication or the underlying condition.

Sometimes a problem with smell can be a sign of a more serious health problem, such as a disease of the nervous system, like Parkinson's disease, Alzheimer's disease, or multiple sclerosis. In rare cases, it can be a sign of a brain tumor. Malnutrition and diabetes also can be accompanied or signaled by chemosensory problems, like smell disorders.

In rare instances, a person can be born without the ability to smell. In other cases, total loss of smell is usually caused by nasal and sinus disease or head injury. If the nerves involved in the sense of smell are severed, either by trauma or surgery, complete loss of smell will occur.

Losing smell can be more than a quality-of-life issue. Loss of smell deprives us of an early warning system that most of us take for granted. Smell helps us detect spoiled food and beverages. It also alerts us to the smoke of a fire, the odor of dangerous fumes, or a gas leak.

Loss of smell can also be a first sign of a more serious condition or disease. In some cases, especially in older people, loss of smell can interfere with normal eating patterns, causing us to eat too much or too little, and may even lead to depression.

Scientists have developed tests to determine the nature and extent of a person's smell disorder. Tests measure the smallest amount of odor patients can detect as well as their accuracy in identifying different smells.

An easily administered "scratch and sniff" test allows a person to scratch pieces of paper treated to release different odors, sniff them, and try to identify each odor from a list of possibilities. In this way, doctors can easily determine whether a person has hyposmia, a decreased ability to smell, anosmia, the inability to detect any odors, or another kind of smell disorder.

Depending on the cause of your smell disorder, your doctor may be able to treat your problem or suggest ways to cope with it. If a certain medication is the cause of the disorder, stopping or changing the medicine may eliminate the problem.

Some patients with respiratory infections or allergies regain their sense of smell when the illness or condition is over. Often, correcting a general medical problem also can restore the sense of smell.

For patients with nasal obstructions, such as polyps, or other inflammatory conditions of the nose or sinuses, medical treatments or surgery can restore the sense of smell. Occasionally, the sense of smell returns to normal on its own, without any treatment.

See your doctor and ask if your medicine could be causing your problem with smell. Some medicines, like antibiotics and high blood pressure pills, are more likely to cause problems. Your doctor may be able to adjust your medicine or change your medicine. If not, he or she may suggest ways to manage your problem.

Do not stop taking your medicine unless directed by your doctor. To reduce unwanted side effects, your doctor may try to find a new medicine for you or reduce the dose of your medicine.

The best thing you can do is see your doctor. Proper diagnosis by a trained professional, such as an otolaryngologist, is important. These physicians specialize in disorders of the head and neck, especially those related to the ear, nose, and throat. Diagnosis may lead to an effective treatment of the underlying cause of your smell disorder.

Many types of smell disorders are curable, and for those that are not, counseling is available to help you cope.

You can help your doctor make a diagnosis by writing down important information about your problem beforehand and giving the information to your doctor during your visit.

Write down answers to the following questions:

• When did I first become aware of the problem?

• Did I have the cold or the flu?

Write down answers to these questions:

• Did I have a head injury?

• Was I exposed to air pollutants, pollens, danders, or dust to which I might be allergic?

• Is this a recurring problem?

• Does it come at any special time, like during the hayfever season?

The National Institute on Deafness and Other Communication Disorders supports basic and clinical studies of smell disorders. Scientists are working to understand more about the sense of smell so that new treatments can be developed to help restore the sense of smell to those who have lost it.

Scientists are finding out more about how our sense of smell works and how we detect and smell the many different compounds that form odors. These findings are helping scientists study the sense of smell as a model for other sensory systems in the body.

Scientists have also found that the loss of smell affects the choices an older person makes about eating certain foods. They are looking at how and why this takes place in order to develop more effective ways to help older people -- especially those with chronic illnesses -- cope better with problems with smell.

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