Scientific studies from Europe in the last few years show that patients allergic to only one of several things (e.g., grass, dust mite, ragweed, or cat) may benefit from sublingual immunotherapy (in which the substance is placed under the tongue rather than given by shots).
Recent studies show SLIT is not very effective for patients with allergies to numerous things. With increased use of SLIT, there are now reports of patients having anaphylaxis at home after taking their doses.
The European studies indicate that for SLIT to be effective, the total dose given in a month should be 50-500 times higher than the dose given by injection (allergy shots).
The high-dose European preparations are not available in the United States.
Nonetheless, some practitioners in the United States (citing the European data) have started to give the allergen extracts available in the U.S. (and manufactured for conventional allergy shots) as drops under the tongue. Unfortunately, this method provides a LOWER dose than is given by conventional allergy shots, and has been proven to be no more effective than placebo. It is not possible to achieve anywhere near the European doses using extracts available in the U.S. Additionally, the extracts being used for SLIT in the United States are being used off-label, as there are no data to support their use in this manner.
Sublingual immunotherapy drops are not currently covered by health insurance companies in the United States because they are ineffective as administered here. Practitioners who bill sublingual drops to insurers are using billing codes intended for conventional allergy shots, which is illegal.
Sublingual immunotherapy tablets for some allergens, including grass pollen and ragweed pollen, are now available and FDA approved. These are appropriate for patients whose main allergen is grass or ragweed pollen, and who wish to receive immunotherapy for these allergens. While sublingual drops remain ineffective, these high dose tablets are effective and offer a treatment option for some patients. Ask your allergist for more information.