Loss of Smell
What is loss of smell?
Loss of smell results from nasal congestion or blockage of the nose, or it can be a sign of a nervous system (neurological) condition. The medical term for loss of smell is anosmia. A partial loss of smell is called hyposmia.
Loss of smell is often caused by conditions affecting the mucous membranes that line the nasal passages. This symptom is frequently reported by individuals infected with the novel coronavirus responsible for COVID-19. Allergic reactions are a common cause of loss of smell. Such reactions may be triggered by pollen (hay fever), animal dander, foods, or medicines.
The sense of smell contributes enormously to the taste and enjoyment of food. Any loss of smell negatively impacts a person’s overall quality of life.
Upper respiratory infections cause inflammation of the nasal passage and are common causes of loss of smell. These infections include the common cold, sinusitis, and influenza. Temporary loss of the sense of smell is common with nasal allergies, such as hay fever (allergic rhinitis). Some medications may also cause loss of smell.
The sense of smell is often lost with disorders that prevent air from reaching the part of the nose where smell receptors are located. These disorders may include nasal polyps, nasal deformities, and nasal tumors. Brain disorders that affect the neural impulses between the brain and receptors in the nose responsible for smell may lead to loss of smell. Such disorders include brain aneurysm or tumor. Even the aging process may affect the transmission of signals between the brain and smell receptors in the nose.
The sudden onset of loss of smell associated with weakness or numbness in the arms or fingers, especially if it occurs on only one side of the body, can be a sign of stroke. Seek immediate medical care (call 911) if you develop weakness or numbness on one side of your body.
Seek prompt medical care if your loss of smell is persistent or causes you concern.
What other symptoms might occur with loss of smell?
Loss of smell may accompany other symptoms, which will vary depending on the underlying disease, disorder or condition. Symptoms that frequently affect the sense of smell may also involve other body systems.
Inflammation or infectious symptoms that may occur along with loss of smell
Loss of smell may accompany temporary or permanent irritation or destruction of the mucous membranes lining the inside of the nose. Symptoms include:
- Redness, warmth or swelling of the lining of the nose
- Runny nose (nasal congestion)
Obstruction symptoms that may occur along with loss of smell
Loss of smell may accompany symptoms related to an obstruction in the nasal passage including:
- Deformity of the nose or airways
- Difficulty breathing
Nervous system and brain symptoms that may occur along with loss of smell
Loss of smell may accompany symptoms related to damage to the central nervous system or brain including:
- New onset or change in pattern of headaches
- Numbness on one side of the body
- Personality or behavior changes
- Speech difficulties
- Weakness on one side of the body
Serious symptoms that might indicate a life-threatening condition
Loss of smell with sudden numbness or weakness of the arm or fingers, especially when it occurs on only one side of the body, can be a sign of stroke. Seek immediate medical care (call 911) if you, or someone you are with, have serious symptoms including:
- Abnormal pupil size or nonreactivity to light
- Change in level of consciousness or alertness, such as passing out or unresponsiveness
- Change in mental status or sudden behavior change, such as confusion, delirium, lethargy, hallucinations and delusions
- Garbled or slurred speech or inability to speak
- Paralysis or inability to move a body part
- Severe headache
What causes loss of smell?
Loss of smell results from conditions affecting the mucous membranes that line the nasal passages. Allergic reactions are a common cause of loss of smell. Such reactions may be triggered by pollen (hay fever), animal dander, foods, or medicines. Upper respiratory infections that cause inflammation of the nasal passages are also common causes of a loss of smell, including the common cold, sinusitis, and influenza. Bacteria, viruses, or fungi may cause infections related to loss of smell.
The sense of smell is often lost with disorders that prevent air from reaching the part of the nose where smell receptors are located. These disorders may include nasal polyps, nasal septal deformities, and nasal tumors.
Inflammatory or infectious causes of loss of smell
Loss of smell may be caused by temporary or permanent irritation or destruction of the mucous membranes lining the inside of your nose including:
- Allergic reactions
- Common cold
- Hay fever or allergic reaction from animal dander, dust, cosmetics or pollen
- Influenza (flu)
- Sjogren’s syndrome
Obstructive causes of loss of smell
Loss of smell can also be caused by obstruction of your nasal passages including:
- Bony deformity inside the nose
- Foreign body
- Nasal polyps
Nervous system and brain causes of loss of smell
Loss of smell can also be caused by damage to the nerve pathways that provide your sense of smell in conditions such as:
- Alzheimer’s disease
- Anxiety disorders
- Chemical exposure to certain insecticides or solvents
- Cocaine abuse
- Medication side effects
- Nutritional deficiency (vitamin B12, niacin, zinc)
- Tumors of the head or brain (olfactory groove meningioma)
Serious or life-threatening causes of loss of smell
In some cases, loss of smell may be a symptom of a serious or life-threatening condition that should be immediately evaluated in an emergency setting. These include:
- Traumatic head or brain injury
- Tumor of the head, nose or brain
Questions for diagnosing the cause of loss of smell
To diagnose your condition, your doctor or licensed health care practitioner will ask you several questions related to your loss of smell including:
- When did you first notice a loss of smell?
- Do you have a cold or other upper respiratory infection?
- Do you have any other symptoms?
- Do you have allergies?
- What medications are you taking?
What are the potential complications of loss of smell?
Because loss of smell can be due to serious diseases, failure to seek treatment can result in serious complications and permanent damage. Once the underlying cause is diagnosed, it is important for you to follow the treatment plan that you and your health care professional design specifically for you to reduce the risk of potential complications including:
- Difficulty breathing
- Spread of cancer
- Structural deformities to nose and sinuses
- Tumor growth and obstructed breathing