What Is Loss of Smell?

A partial or total loss of smell—called anosmia—can happen for many reasons—including having COVID-19. Loss of smell can also affect your sense of taste. In fact, the two senses are so closely connected that people who are losing their sense of smell often mistakenly believe they are losing their sense of taste.

A loss of smell is most often temporary, depending on the cause.

Anosmia Causes

Many conditions can temporarily or permanently cause anosmia. More rarely, a decreased sense of smell can signal the start of a serious condition such as Alzheimer's disease or Parkinson's disease. Some people are born with a diminished or heightened ability to smell as compared to others.

In general, our ability to smell may wax and wane over our lifetime, and most of us begin to lose our sense of smell after the age of 60.

Studies also show that women tend to have a more accurate sense of smell than men.

In addition to a diminished sense of smell and taste, people who suffer from anosmia may also have other symptoms, depending on the cause of their anosmia. These symptoms vary widely. You should report any unusual symptoms to your healthcare provider, even if you don't think they're relevant, since they may indicate an underlying condition.

If you're concerned that you may be losing your sense of smell, it's likely you have a common and temporary condition. Keep in mind that each individual and case is different, so whether or not your diminished sense of smell persists will depend on your individual circumstances.

The following conditions can cause anosmia that is often temporary or reversible:

• Allergies
• Congestion from colds or upper respiratory infections
• Dental problems or oral surgery
• Deviated septum
• Nasal polyps (often must be treated surgically)
• Sinusitis
• Temporary fluctuations in hormone levels
• Vitamin deficiencies or malnutrition (rare)

The loss of smell due to some conditions or risk factors may be reversible, partially reversible, or permanent. For example, once a person quits smoking, their sense of smell usually improves—but how much the ability to smell returns is variable.

Medication side effects that cause loss of smell may be temporary or permanent, depending on the medication.

The use of cocaine or other drugs that are snorted up the nose can also cause anosmia. Like smoking, a person's ability to smell may or may not return when the drug is stopped or may only partially return.

The list of medications that may alter a person's ability to smell or taste is very long, but it includes many:

• Antibiotics
• Antidepressants
• Blood pressure medications
• Heart medications

Associated Conditions

Many conditions often cause a permanent loss of a person's sense of smell. Again, keep in mind that each case is different, and some people may regain their sense of smell even with these conditions, though many do not.

Brain injuries (head trauma) may cause anosmia, as can disorders that affect the nervous system, including:

• Parkinson's disease
• Multiple sclerosis
• Alzheimer's disease

Radiation treatment to the head and neck may also cause anosmia.

Some other conditions that may cause anosmia include:

• Adrenocortical insufficiency syndrome
• Cerebral vascular accident (stroke)
• Cushing's syndrome
• Diabetes
• Epilepsy
• Kallmann's syndrome
• Hypothyroidism
• Psychiatric conditions
• Sjögren's disease
• Systemic lupus erythematosus
• Tumors of the brain, sinus cavities, or nose
• Turner syndrome

Diagnosis

Your healthcare provider will review your medical history as well as any current symptoms you might be having. Your practitioner will probably also perform a physical exam.

If warranted, a healthcare provider will order blood tests to rule out risk factors, such as infections or hormonal disturbances, or a computerized tomography (CT) scan or magnetic resonance imaging (MRI) to diagnose nasal polyps or tumors.

Treatment

As mentioned above, many conditions that can diminish your sense of smell are reversible, but it depends on the root cause of your condition.

Nasal polyps or deviated septums can be treated surgically, sinusitis can sometimes be treated with antibiotics, and allergies can be treated with medications.

If the anosmia is a side effect of a medication you are taking, the medication should be stopped.

There is no medication or treatment specifically designed to improve or bring back your sense of smell, but finding the cause of the anosmia and resolving the underlying issue is successful in many cases. In some cases, the sense of smell may return gradually.

When to See a Healthcare Provider

Any unexplained loss of smell that lasts longer than a cold virus probably should be checked out by a healthcare provider. Call your practitioner immediately if your inability to smell comes on suddenly and is accompanied by other worrisome or strange symptoms.