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. 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 term osmophobia comes from the Greek ὀσμή - osmē, meaning "smell, odour" and φόβος - phobos, "fear". Olfactophobia comes from the Latin olfacto, "to smell at".