Anosmia is losing the the sense of smell. The word is also used for people who never had this sense. The loss can be temporary, or permanent. The conditions that cause a temporary loss of this sense include:
- Upper respiratory tract infection, for example a common cold
- Blocking the nose, for example through seasonal allergies, or a nasal polyp.
- Side-effects of certain drugs or of certain poisons.
- Concussion, brain tumors.
Smelling things depends on two nerves (Nervus olfactorius and Nervus trigeminus), as well as the part of the brain which processes the information. Damage to this system will affect the sense of smell; permanent damage may lead to a permanent loss of the sense of small.
There are tests that can be done to find the cause of the problem.
Note also that the sense of smell changes with age. Anosmia can also point to different neurological conditions such as Parkinson's disease, Alzheimer's disease, or Schizophrenia. Certain plants, such as tobacco also contain substances which change olfaction.
In general, anosmia which has its cause in the brain cannot be treated. Anosmia which is caused by blocking the nose can be treated by removing the block. In some cases, accupuncture was successfully used to treat anosmia.