While the loss of the sense of smell or anosmia is not usually a serious condition, it can affect quality of life. It may lead to a loss of appetite as the sense of smell also aids in tasting flavor. There are many causes of a loss of sense of smell and some are temporary while others, permanent. In some cases, it can signal a serious underlying medical condition. It can be deadly if a person is in a building with a gas leak or fire that he cannot smell. If an unexplained loss of smell occurs, it is best to consult a physician for evaluation.
Colds and Flus
A viral infection that causes the common cold or the flu can lead to a temporary loss of sense of smell, states the Mayo Clinic. There can be temporary damage or inflammation to the mucus membrane in the nose, which can lead to congestion, runny nose and difficulty smelling. Colds and flus usually resolve within a couple of weeks, and the sense of smell should return.
Allergies and Nasal Polyps
The American Rhinologic Society claims that allergies and nasal congestion can cause irritation to the nasal passages that can contribute to a loss of sense of smell. Exposure to cigarette smoke and pollution can cause the same type of irritation. Nasal polyps or small growths in the nasal cavity can block smells from reaching the nerves that help the brain identify smells.
Head Injuries and Disorders
According to “The Merck Manual for Healthcare Professionals”, any kind of trauma to the head or a disease that affects brain function can contribute to a loss of sense of smell. This includes Alzheimer’s disease, stroke, brain aneurysms, multiple sclerosis, Parkinson’s disease, Sjogren’s syndrome, seizure disorders, brain tumors and more. If a loss of smell is sudden and severe and not attributed to a cold or allergy, it could be a sign of a more serious disease.
Drugs and Toxins
Certain medications can also cause a loss of smell as a side effect. This includes amphetamines, hormone replacement therapies, decongestants, antifungals, antibiotics and medications used to treat heart disease. In addition, exposure to high levels of toxins such as cadmium, manganese, insecticides and solvents can also cause this symptom. Exposure to radiation during treatment for cancer can lead to damage that hinders the ability to smell.