Timothy C. Hain, M.D.
Allergies are unwanted reactions of the immune system to foreign substances -- typically inhaled pollon, but also foods, rubber such as latex -- nearly anything that people contact. We are not going to discuss allergy in general, as this topic is far too large. Instead, we will focus on allergy as it relates to dizziness and hearing.
Allergy has been growing rapidly, perhaps due to greater contact with pollutants. For example, in China, the prevalence of asthma increased almost 5 fold in Shanghai betwen 1990 and 2012 (Huang et al, 2015).
The connection between allergy and dizziness or hearing disorders is generally indirect, and sometimes controversial. The general logic is that allergy must in some way affect the ear or its connections within the nervous system. Breaking this down further, we need to consider the outer ear, external ear canal, ear drum (#1) middle ear, mastoid sinus, eustachian tube (#10), inner ear, 8th nerve (6-8), and central connections in the brainstem.
Outer ear: allergy could theoretically block the outer ear through swelling. This is not impossible but rare.
The external ear canal could become swollen as well. Again, not impossible but rare.
Allergy generally does not affect the ear drum. The middle ear, however, can be affected by allergy through accumulation of fluid and abnormal pressure through blockage of the eustachian tube.
Allergy is generally thought not to affect the inner ear, but there may be a combined susceptibilty to allergy and Meniere's disease (Sen et al, 2005).
Allergy is also not generally thought to affect the 8th nerve.
There is a substantial literature suggesting that allergy might cause migraine, which can in turn cause dizziness. Several authors have suggested that food allergy might cause migraine (Hernandez 2007; Egger et al, 1983; Mansfield et al, 1985). Martin et al reported that allergy treatment reduces migraine.
There are two main types of allergy testing - -scratch and blood testing.