Osmophobia or olfactophobia refers to a fear, aversion, or psychological hypersensitivity to odors. The phobia generally occurs in chronic migraine sufferers who may have odor triggered migraines.^{[citation needed]} 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. The condition may also be present in individuals in substance withdrawal, specifically opioid withdrawal syndrome, where it is usually associated with nausea and/or vomiting.

The term osmophobia comes from the Greek ὀσμή - osmē, meaning "smell, odour"^[1] and φόβος - phobos, "fear".^[2] Olfactophobia comes from the Latin olfacto, "to smell at".^[3]