If you lose your sense of smell, you'll miss more than a variety of scents. Without a good sense of smell, you may find that food tastes bland and it's hard to tell different foods apart. Loss of smell can be partial (hyposmia) or complete (anosmia), and may be temporary or permanent, depending on the cause.
Even a partial loss of smell could cause you to lose interest in eating, which in extreme cases, might lead to weight loss, poor nutrition or even depression. Some people add more salt to bland foods, which can be a problem if you have high blood pressure or kidney disease. Your sense of smell is also crucial for warning you of potential dangers such as smoke or spoiled food.
A stuffy nose from a cold is a common cause for a partial, temporary loss of smell. A blockage in the nasal passages caused by a polyp or a nasal fracture also is a common cause. Normal aging can cause a loss of smell too, particularly after age 60.
What is smell?
Your nose and an area in the upper throat have special cells that contain odor receptors. When these receptors detect smells, they send a message to the brain. The brain then identifies the specific smell.
Any problem in this process — a stuffy nose, a blockage, inflammation, nerve damage or a brain function condition — can affect your ability to smell normally.
Problems with the inner lining of your nose
Conditions that cause temporary irritation or congestion inside your nose may include:
- Acute sinusitis (nasal and sinus infection)
- Common cold
- Hay fever (allergic rhinitis)
- Influenza (flu)
- Nonallergic rhinitis (chronic congestion or sneezing not related to allergies)
Obstructions of your nasal passages
Conditions or obstructions that block the flow of air through your nose can include:
- Deviated septum
- Nasal polyps
Damage to your brain or nerves
Nerves leading to the area of the brain that detects smell or the brain itself can be damaged or deteriorate due to:
- Alzheimer's disease
- Brain aneurysm (a bulge in an artery in your brain)
- Brain surgery
- Brain tumor
- Exposure to chemicals in certain insecticides or solvents
- Huntington's disease
- Kallmann's syndrome (a rare genetic condition)
- Klinefelter syndrome (a rare condition in which males have an extra X chromosome in most of their cells)
- Korsakoff's psychosis (a brain disorder caused by the lack of thiamin)
- Poor nutrition
- Medications (for example, some high blood pressure medications, antibiotics and antihistamines)
- Multiple sclerosis
- Paget's disease of bone (a disease that affects your bones, sometimes facial ones)
- Parkinson's disease
- Niemann-Pick (Pick's disease, a form of dementia)
- Radiation therapy
- Sjogren's syndrome (an inflammatory disease that generally causes dry mouth and eyes)
- Traumatic brain injury
- Zinc deficiency
- Zinc-containing nasal sprays (taken off the market in 2009)
When to see a doctor
Loss of smell caused by colds, allergies or sinus infections usually clears up on its own after a few days. If this doesn't happen, consult your doctor so that he or she can rule out more-serious conditions.
Additionally, loss of smell can sometimes be treated, depending on the cause. Your doctor may give you an antibiotic to treat a bacterial infection, or remove anything blocking your nasal passage. But in some cases, loss of smell can be permanent.