Definition

Impaired smell is the partial or total loss or abnormal perception of the sense of smell.

Alternative Names

Loss of smell; Anosmia; Hyposmia; Parosmia; Dysosmia

Considerations

The loss of smell can occur with conditions that prevent air from reaching smell receptors located high in the nose, or loss of or injury to the smell receptors. Loss of smell is not serious, but can sometimes be a sign of a nervous system condition.

Temporary loss of the sense of smell is common with colds and nasal allergies, such as hay fever (allergic rhinitis). It may occur after a viral illness.

Some loss of smell occurs with aging. In most cases, there is no clear cause, and there is no treatment.

The sense of smell also enhances your ability to taste. Many people who lose their sense of smell also complain that they lose their sense of taste. Most can still tell between salty, sweet, sour, and bitter tastes, which are sensed on the tongue. They may not be able to tell between other flavors. Some spices (such as pepper) may affect the nerves of the face. You may feel rather than smell them.

Causes

Loss of smell can be caused by:

• Medicines that change or decrease the ability to detect odors, such as amphetamines, estrogen, naphazoline, trifluoperazine, long-term use of nasal decongestants, reserpine, and possibly zinc-based products
• Blockage of the nose due to nasal polyps, nasal septal deformities, and nasal tumors
• Infections in the nose, throat, or sinuses
• Allergies
• Endocrine disorders
• Dementia or other neurological problems
• Nutritional deficiencies
• Head injury
• Nasal or sinus surgery
• Radiation therapy to the head or face

Home Care

Treating the cause of the problem may correct the lost sense of smell. Treatment can include:

• Antihistamines (if the condition is due to an allergy)
• Changes in medicine
• Surgery to correct blockages
• Treatment of other disorders
• Olfactory retraining therapy using familiar odors can help improve the sense of smell in a minority of patients

Avoid using too many nasal decongestants, which can lead to repeated nasal congestion.

If you lose your sense of smell, you may have changes in taste. Adding highly seasoned foods to your diet can help stimulate the taste sensations that you still have.

Improve your safety at home by using smoke detectors and electric appliances instead of gas appliances. You may not be able to smell gas if there is a leak. Or, install equipment that detects gas fumes in the home. People with smell loss should label when food items were opened to prevent eating spoiled food.

There is no treatment for loss of smell due to aging.

If you have a loss of smell due to a recent upper respiratory infection, be patient. The sense of smell often returns to normal without treatment.

When to Contact a Medical Professional

Contact your health care provider if:

• The loss of smell continues or is getting worse.
• You have other unexplained symptoms.

What to Expect at Your Office Visit

The provider will perform a physical exam and ask questions about your medical history and current symptoms. Questions may include:

• When did this problem develop?
• Are all odors affected or only some? Is your sense of taste affected?
• Do you have cold or allergy symptoms?
• What medicines do you take?
• Do you have any other symptoms?

The provider will look at and around your nose. Tests that may be performed include:

• CT scan
• MRI scan
• Nasal endoscopy
• Olfactory nerve testing
• Smell testing

If the loss of sense of smell is caused by a stuffy nose (nasal congestion), decongestants or antihistamines may be prescribed.

Other treatments for a stuffy nose may include:

• A vaporizer or humidifier may help keep mucus loose and moving.
• Steroid nasal sprays or pills may be recommended.
• Vitamin A may be given by mouth or as a shot.
• Nasal steroid sprays may be prescribed.

References

Baloh RW, Jen JC. Smell and taste. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 395.

Whitcroft KL, Hummel T. Olfactory function and dysfunction. In: Flint PW, Francis HW, Haughey BH, et al, eds. Cummings Otolaryngology: Head and Neck Surgery. 7th ed. Philadelphia, PA: Elsevier; 2021:chap 36.