Losing the sense of smell touches many parts of life. Without a good sense of smell, food might taste bland. It can be hard to tell one food from another.

Losing some of the sense of smell is called hyposmia. Losing all sense of smell is called anosmia. The loss might be brief or long term, depending on the cause.

Losing even some sense of smell can cause a loss of interest in eating. Not eating might lead to weight loss, poor nutrition or even depression.

The sense of smell can warn people of dangers, such as smoke or spoiled food.

Causes

A stuffy nose from a cold is a common cause for a partial, brief loss of smell. A polyp or swelling inside the nose can lead to a loss of smell. Aging can cause a loss of smell, especially after age 60.

What is smell?
The nose and an area in the upper throat have special cells, called receptors, that discern odors. These receptors send a message to the brain about each smell. The brain then figures out what the smell is.

Any problem along the way can affect the sense of smell. Problems can include a stuffy nose; something that blocks the nose; swelling, called inflammation; nerve damage; or an issue with how the brain works.

Problems with the inner lining of the nose
Conditions that cause congestion or other issues inside the nose may include:

Acute sinusitis
Chronic sinusitis
Common cold
Coronavirus disease 2019 (COVID-19)
Hay fever (allergic rhinitis)
Influenza (flu)
Nonallergic rhinitis
Smoking
Blockages in the inside of the nose, called the nasal passages
Conditions that block the flow of air through the nose can include:

Nasal polyps
Tumors
Damage to your brain or nerves
The following can cause damage to the nerves to the area of the brain that picks up smells or to the brain itself to:

Aging
Alzheimer’s disease
Being around toxic chemicals, such as those used in solvents
Brain aneurysm
Brain surgery
Brain tumor
Diabetes
Huntington’s disease
Hypothyroidism (underactive thyroid)
Kallmann’s syndrome (a rare genetic condition)
Korsakoff’s psychosis, a brain condition caused by the lack of vitamin B-1, also called thiamin
Lewy body dementia
Medicines, such as some for high blood pressure, some antibiotics and antihistamines, and some nasal sprays
Multiple sclerosis
Parkinson’s disease
Poor nutrition, such as too little zinc or vitamin B-12 in the diet
Pseudotumor cerebri (idiopathic intracranial hypertension)
Radiation therapy
Rhinoplasty
Traumatic brain injury

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