Nasal sprays are used as local treatments for conditions such as
nasal congestion and
allergic rhinitis. In some situations, nasal delivery route is preferred because it provides an agreeable alternative to injection or pills. Substances can be assimilated extremely quickly and directly through the nose. Many pharmaceutical drugs exist as nasal sprays for systemic administration (e.g. treatments for pain,
migraine,
osteoporosis and
nausea). Other applications include
hormone replacement therapy, treatment of
Alzheimer's disease and
Parkinson's disease. Nasal sprays are seen as a more efficient way of transporting drugs with potential use in crossing the blood–brain barrier.