Sublingual immunotherapy involves the administration of a diluted dose of an allergen under the tongue, which allows the material to contact the oral mucosa. Sublingual immunotherapy has been investigated in patients with allergic rhinitis and/or asthma associated with sensitivity to seasonal allergens, and to allergens such as dust mites, mold, pet dander, or nuts. In contrast to standard immunotherapy, which requires subcutaneous injections, sublingual therapy may offer a lower risk of serious side effects, and may be more comfortable and acceptable to many patients.