Sublingual medications are placed under the tongue where they dissolve rapidly. The tissues of the mouth, especially those under the tongue, readily absorb most types of medications that are made to dissolve quickly in a moist environment. Sublingual immunotherapy is often preferable to the injectable forms, especially when the patient is a small child.

This form of immunotherapy is gaining popularity with patients who have food allergies. Because this type of immunotherapy is somewhat less effective than the injectable form, the dosage may need to be adjusted more often to maintain a positive response. It may also take longer to reach a maintenance dose when this type of immunotherapy treatment is used.