Smell and taste are important senses. They can help you enjoy life—smell the flowers or savor your meal. They can also keep you safe. The smell of smoke can alert you to danger.

As you get older, your sense of taste or smell may fade. These senses are related. So when you can’t smell, you may also find that food tastes bland.

Often, loss of smell or taste isn’t cause for concern. It can be caused by many things. People with certain viruses can temporarily lose one or both senses.

When undergoing radiation and other cancer treatments, people may experience loss of smell and taste. This should return after the treatment stops.

Certain medications can also affect smell or make food taste different. An infection in the mouth, like gum disease, can leave a bad taste, too.

Sometimes the loss of smell or taste can be a sign of a more serious problem. Losing your sense of smell, for example, may be a symptom of Parkinson’s or Alzheimer’s disease. Tell your health care provider if you have any change in your sense of smell or taste.

If you’re having trouble smelling and tasting, adding colorful foods and spices to a dish can help. Try choosing brightly colored vegetables, like carrots or broccoli. Spices like mustard, garlic, and ginger can liven up a meal.

Smell and taste loss are relatively common problems that have a tremendous impact on a person’s quality of life. While the sensory systems of smell (olfaction) and taste (gustation) are often grouped together clinically, each has its own unique features and potential clinical problems. The brain processes taste and smell differently, so damage to either sense can cause different types of problems, depending on the degree of dysfunction.

Fortunately, a complete loss of smell, taste, or both, is rare, and individuals can often compensate for partial loss. Also, taste and smell are the only sensory systems that have the capacity to regenerate after damage, so some recovery of function is usually possible.

Major determinants of taste and smell loss include:

• Sex and age
  • Age-related smell loss is more prominent in men.
  • Taste is more resistant to age-related loss.
• Environment
  • Airborne toxic odors can permanently damage the sense of smell.
• Trauma
  • Frontal head injury can permanently damage the sense of smell.
• Disease or illness
  • Chronic rhinitis and allergies can adversely affect the sense of smell and reduce the appreciation of food; the effect may be short-term or permanent.
  • Infections of the middle ear can partially damage the sense of taste.
• Prescription medications
  • Certain prescription drugs can affect taste quality perception.
• Cancer treatment
  • Chemotherapy and radiation treatment for head and neck cancer can damage the sense of taste.

Mild taste and smell loss often goes unnoticed. Some smell loss may accompany seasonal nasal congestion or a head cold. This type of smell loss usually goes unreported and unmeasured, because people generally consider it to be a temporary and mild annoyance.

More serious smell loss can be caused by nasal obstruction that requires corrective surgery or by chronic viral infections with swelling that require special medications. This type of loss could be dangerous because an individual may fail to detect smoke or spoiled food. It is sufficiently distressing that the patient may seek help.

Otolaryngologists—sometimes called otorhinolaryngologists—are physicians who specialize in diseases of the ear, nose, and throat, including problems affecting taste and smell. An otolaryngologist will conduct a physical examination of the nose and mouth and perform customized tests to assess the degree of any smell and/or taste loss.

As part of the exam, the physician will take a personal history and ask the patient to complete a questionnaire to fully describe the problem ("self-reporting"). It is very important that the physician diagnose whether the loss is due to a problem with the sense of smell, taste, or both. In many cases, patients claim a loss of taste because food has become less enjoyable or seems bland, but testing shows that the problem actually involves the sense of smell.

This example points to a very important interaction between taste and smell: our appreciation of food flavor is a complicated mix of taste (sweet, sour, salty, bitter), smell (aromas), texture (smoothness), and temperature (hot and cold) sensations felt through chewing or drinking. Food aromas generated by chewing activate the sense of smell by way of a special channel in the roof of the throat. If this channel is blocked due to nasal inflammation, for example, aromas can not reach the person’s sense of smell, and a major contributor to the enjoyment of flavor is lost.

Unlike hearing or vision tests, the tests to measure taste and smell loss are not based upon a standard, internationally-accepted procedure. There are several different tests for taste and smell, and the choice of test may be due to convenience, ease-of-use, the nature of the loss, and cost.

In the clinical setting in the United States, where time, cost, and insurance are critical factors, smell loss is usually assessed with a "scratch-and-sniff" test. This test consists of a booklet with 10–40 individual sheets that have microencapsulated beads impregnated with specific odors. The patient scratches the beads with a pencil to release the odor and then identifies the odor from a list of five choices. This type of test measures one’s ability to recognize a particular odor, but does not measure one’s sensitivity or threshold to certain smells. Once the test is completed, the number of errors is recorded and then compared against a standard number of responses by normal individuals. This type of test is relatively quick (under 30 minutes), novel, and fun. The test assumes a normal level of cognitive function, so it is not suitable for individuals with dementia and other types of neurodegenerative disease.

A more exacting test of smell function can be conducted in the academic research environment or in clinical trials. In these cases, patients are recruited to participate in a series of tests in which time and convenience are secondary to a more thorough examination. These examinations can include measures of threshold sensitivity and odor identification. The test equipment is often customized and not suitable for a physician’s office. Its use requires special training.

An "olfactometer" is an odor delivery system that allows the technician to pass precise concentrations of a known odor to the nose of the patient. The patient indicates the lowest concentration that is detectable, and names the odor. In this way, the patient’s smell response profile can be determined and compared against a normal standard.

An accurate assessment of smell loss includes:

• Physical examination of the ears, nose, and throat.
• Personal history (for example, exposure to toxic chemicals or trauma).
• Questionnaire (self-report).
• Validated test supervised by a health care professional.
• Discussion of treatment options, such as surgery, antibiotics, or steroids.

The sense of taste regulates food intake and choice and is essential for life. Consequently, the brain organization of the sense of taste is complicated and redundant. It is very difficult to damage the taste system completely without a threat to life. Specialized taste cells are located throughout the tongue, roof of the mouth, and throat, so it is very difficult to test the entire system.

Two types of taste tests are used. The first test uses "whole mouth stimulation" or the "sip and spit" method. In this method, a solution of a known concentration of a sweet, salty, bitter, or sour substance is gargled and sloshed in the mouth and then discarded. The patient is asked to identify the taste substance, and the concentration can be varied to determine threshold sensitivity. It is an easy test to administer but assumes severe taste loss. Regional damage (for example, on the front or tip of the tongue) would be masked by stimulation of the remaining taste cells elsewhere in the mouth.

The second test uses a more localized application of taste substances. In this test, filter paper or a dissolvable strip is impregnated with a known concentration of a sweet, salty, bitter, or sour substance, and the filter paper or strip is placed on a specific part of the tongue or palate. The patient is asked to identify the taste substance. The concentration can be varied to determine threshold sensitivity. This test is also easy to administer. The goal is to activate major regions of taste cells to determine whether the individual has partial taste deficit or damage.

An accurate assessment of taste loss includes:

• Physical examination of the ears, nose, and throat.
• Dental examination and assessment of oral hygiene.
• Personal history (for example, trauma to mouth, cancer, or medications).
• Questionnaire (self-report).
• Validated test supervised by a health care professional.
• Discussion of treatment options, such as proper oral hygiene or different medications.

Smell and taste contribute greatly to our food choices, diet, nutrition, and overall health status. Studies have demonstrated that the ability to recognize some tastes is apparent at birth—for example, the pleasure response to sweetness and the disgust at bitterness. A response to salt develops during the first year of life. There is considerable genetic and cultural variability in our food preferences, and these have significant associations with a variety of health risk factors such as obesity, high blood pressure, and cardiovascular disease.

A genetic trait in humans (although it may be modified by external or environmental causes) is the ability or inability to taste the bitter quality of two related substances: phenylthiocarbamide (PTC) or 6-n-propylthiouracil (PROP). Tasters of PROP and especially super-tasters (those who rate PROP as being extremely bitter) have been shown to have a more intense appreciation for other tastes, such as other bitter substances, sweet, salt, and acidic tastes. Super-tasters, tasters, and non-tasters of PROP may be described as living in different sensory worlds, with super-tasters experiencing a neon world and non-tasters experiencing a pastel world. Tasters and non-tasters may also have differing health risk profiles, including increased or decreased susceptibility to certain diseases, and preference or tolerance for tea, coffee, alcohol, or cigarettes. This is a relatively new and growing field of investigation.

A complete loss of the ability to smell (anosmia) or taste (ageusia), although rare, may seem insignificant compared to blindness and deafness. Sufferers of these conditions, however, describe their lives as being nearly unbearable since they are deprived of the many pleasant tastes and odors of daily living. The consequences of the more common conditions of a reduced or diminished ability to smell (hyposmia) or taste (hypogeusia) go well beyond the inconvenience of a bland meal. Impairment of smell or taste could result in eating spoiled or contaminated food or not being aware, through smell, of a gas leak. Some patients complain not of smell or taste loss but, instead, of distortions such as persistent unpleasant or painful sensations described as bad, foul, rancid, acidic, metallic, or burning. These problems may result in diagnosis of a condition known as dysgeusia (altered or abnormal tastes) or burning mouth syndrome. Such patient complaints increase with age and lead to major quality of life issues.

Did you know that your sense of smell and taste are connected? As you get older, these senses can change, and, like Sally, you may find that certain foods aren’t as flavorful as they used to be. Changes in smell or taste can also be a sign of a larger problem.

Your Sense of Smell

Smell is an important sense. Certain smells, like your dad’s cologne, can help you recall a memory. Other smells, like smoke from a fire, can alert you to danger. When you can’t smell things you enjoy, like your morning coffee or spring flowers, life may seem dull.

As you get older, your sense of smell may fade. Your sense of smell is closely related to your sense of taste. When you can’t smell, food may taste bland. You may even lose interest in eating.

What Causes Loss of Smell?

Many problems cause a loss of smell that lasts for a short time. This temporary loss of smell may be due to:

• A cold or flu that causes a stuffy nose. The ability to smell will come back when you’re better.

• Coronavirus infection, which sometimes causes a new loss of smell. You should regain your sense of smell after all other symptoms have gone away, however if it doesn’t return, seek medical care as soon as possible.

• Allergies. Try to stay away from things you’re allergic to, like pollen and pets. Talk to your doctor about how to manage your allergies.

• A harmless growth (called a polyp) in the nose or sinuses that gives you a runny nose. Having the growth removed may help.

• Some medications like antibiotics or blood pressure medicine. Ask your doctor if there is another medicine you can take.

• Radiation, chemotherapy, and other cancer treatments. Your sense of smell may return when treatment stops.

Some things can cause a long-lasting loss of smell. A head injury, for example, can damage the nerves related to smell.

Sometimes, losing your sense of smell may be a sign of a more serious disorder, such as Parkinson’s disease, mild cognitive impairment, or Alzheimer's disease. Be sure to tell your doctor about any change in your sense of smell.

Smells Can Keep You Safe

It’s important to be aware of odors around you. You need to be able to detect smoke, gas leaks, spoiled food, and vapors from potentially dangerous household chemicals.

• Smoke — check your smoke detectors once a year to make sure they work.
• Gas leaks — make sure you have a gas detector in your home.
• Spoiled food — throw out food that’s been in the refrigerator too long.
• Household chemicals — make sure there is fresh air where you live and work.

These safety measures are especially important if your sense of smell has diminished.

Your Sense of Taste

There are tiny taste buds inside your mouth: On your tongue, in your throat, even on the roof of your mouth. What we call “flavor” is based on five basic tastes: sweet, salty, bitter, sour, and savory. These flavors — plus the sensations of heat, coolness, and texture, combine inside the mouth to give us a sense of taste. Along with how it tastes, how food smells is also part of what makes up its flavor.

When food tastes bland, many people try to improve the flavor by adding more salt or sugar. This may not be healthy for older people, especially if you have medical problems like high blood pressure or diabetes (high blood sugar).

People who have lost some of their sense of taste may not eat the foods they need to stay healthy. This can lead to other issues such as:

• Weight loss
• Malnutrition (not getting the calories, protein, carbohydrates, vitamins, and minerals you need from the food)

Eating food that is good for you is important to your health. If you have a problem with how food tastes, be sure to talk with your doctor.

What Causes Loss of Taste?

Many things can cause you to lose your sense of taste. If the salivary glands are damaged or aren’t producing enough saliva, this can affect taste. Most of the time there are ways to help with the problem.

A new loss of taste is a symptom that can occur with coronavirus infection. You should regain your sense of taste after all other symptoms have gone away, however if it doesn’t return, seek medical care as soon as possible.

Medications, like antibiotics and pills to lower cholesterol and blood pressure, can sometimes change how food tastes. Some medicines such as those for high blood pressure, depression, and bladder-control issues can make your mouth dry. Having a dry mouth can cause food to taste funny and also make it hard to swallow. Talk to your doctor if you think a medicine is affecting your sense of taste. There may be different medicines that you can try. Do not stop taking your medicine.

Gum disease, an infection in your mouth, or issues with your dentures can leave a bad taste in your mouth that changes the way food tastes. Brushing your teeth, flossing, and using mouthwash can help prevent these problems. Talk to your dentist if you have a bad taste in your mouth that won’t go away.

Alcohol can alter how food tastes. Cutting back or stopping drinking may help. Smoking can also reduce your sense of taste. Quitting may help.

Cancer Treatments and Taste

People who are having cancer treatments might have a problem with taste. Your sense of taste will often return once treatments stop.

Cancer treatments can make food taste bad or “off.” Some say that food tastes metallic. This funny taste may keep some people from eating healthy food. If this happens to you, try to:

• Eat four or five small meals during the day instead of three large meals.
• Eat cold food, including yogurt, pudding, and gelatin dessert. Cold food may taste better than hot food.
• Eat fresh, uncooked vegetables. Cooked vegetables can have strong odors that may not be appealing.
• Drink lots of fluids, including water, weak tea, juice, and ginger ale.
• Test new foods to find ones you like.
• Brush your teeth before and after eating.
• Use plastic forks and spoons if food tastes metallic.
• If food tastes bland, marinate foods to improve their flavor or add spices to foods.
• If red meat tastes strange, switch to other high-protein foods such as chicken, eggs, fish, peanut butter, turkey, beans, or dairy products.
• If foods taste salty, bitter, or acidic, try sweetening them.
• If you have a bad taste in your mouth, try sugar-free lemon drops, gum, or mints.

Colors and Spices Can Help

If you’re having trouble smelling and tasting your food, try adding color and texture to make your food more interesting. For example, try eating brightly colored vegetables like carrots, sweet potatoes, broccoli, and tomatoes. Also, if your diet allows, flavor your food with a little butter, olive oil, cheese, nuts, or fresh herbs like sage, thyme, or rosemary. To put some zing in your food, add mustard, hot pepper, onions, garlic, ginger, different spices, or lemon or lime juice. Choose foods that look good to you.

An Otolaryngologist: A Specialist for Smell and Taste

If the foods you enjoy don’t smell or taste the way you think they should, talk to your doctor. He or she might suggest you see a specialist who treats people with smell and taste problems.This kind of doctor is called an otolaryngologist (oh-toh-lar-ing-gol-uh-jist), also known as an ENT (which stands for ear, nose, and throat). An otolaryngologist works on problems related to the ear, nose, and throat, as well as the larynx (voice box), mouth, and parts of the neck and face. The doctor may ask:

• Can you smell anything at all?
• Can you taste any food?
• When did you first notice the problem?
• Is the problem getting worse?
• Have you been told that you have allergies or chronic sinus problems?
• What medicines do you take?

There are likely ways to help fix the problem. If not, the doctor can help you cope with the changes in smell and taste.