Osmophobia or olfactophobia refers to a fear, aversion, or psychological hypersensitivity

Hypersensitivity

Hypersensitivity refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity. These reactions may be damaging, uncomfortable, or occasionally fatal. Hypersensitivity reactions require a pre-sensitized state of the host. The four-group classification...

 to smell

Smell

Smell may refer to:* Olfaction, sense of smell, the ability of humans and other animals to perceive odors* Odor, the percept resultant from the sense of smell...

s or odor

Odor

An odor or odour is caused by one or more volatilized chemical compounds, generally at a very low concentration, that humans or other animals perceive by the sense of olfaction. Odors are also commonly called scents, which can refer to both pleasant and unpleasant odors...

s. The phobia

Phobia

A phobia is a type of anxiety disorder, usually defined as a persistent fear of an object or situation in which the sufferer commits to great lengths in avoiding, typically disproportional to the actual danger posed, often being recognized as irrational...

 generally occurs in chronic migraine

Migraine

Migraine is a chronic neurological disorder characterized by moderate to severe headaches, and nausea...

sufferers who may have odor triggered migraines. Such migraines are most frequently triggered by foul odors, but the hypersensitivity may extend to all odors. One study found as many as 25% of migraine sufferers had some degree of osmophobia.

Some migraineurs treat their migraines with some success using pleasant odors, such as mint or lavender.