Sublingual Immunotherapy

Sublingual immunotherapy (SLIT) is similar to allergy shots in that it is a form of allergy immunotherapy. (Allergy shots are known as subcutaneous immunotherapy or SCIT.)

Both SLIT and SCIT treat allergies by exposing the body to liquid antigen that helps desensitize the immune system to allergic triggers. The big difference
is that with subcutaneous immunotherapy, the antigen enters the bloodstream by way of injection. With sublingual immunotherapy, the antigen is dispensed
under the tongue through oral drops and absorbs into the bloodstream through specialized oral cells.

Sublingual immunotherapy is safer than allergy shots. In fact, it has even been shown to be safe for children less than 5 years old.1 (Shots are not usually appropriate for kids younger than 7.) Because of allergy drops’ heightened safety profile, they can be taken at home, which is perhaps the biggest advantage of sublingual immunotherapy. (Most allergy shot programs require patients to report to the doctor’s office a couple times a week for shots.)

Sublingual immunotherapy has been widely prescribed since the mid-1980s. In many parts of Europe, it is prescribed at least as often as allergy shots are. In the U.S., it is becoming increasingly popular as fewer people have time to go to the doctor’s office for allergy shots.

There is also an impressive body of sublingual immunotherapy research. The Cochrane Collaboration, World Health Organization and ARIA guidelines (Allergy Rhinitis and its Impact on Asthma) all affirm SLIT as do hundreds of research studies. In fact, the 2007 ARIA guidelines showed that according to World Health Organization standards, SLIT has surpassed SCIT in terms of the amount of modern evidence in it support and the quality of that evidence.

How do you know if you are a candidate for sublingual allergy immunotherapy?

While medications like pills and nasal sprays may be enough to keep allergies in check for some allergy sufferers, one big drawback is that they only treat the symptoms of allergy. Only sublingual allergy immunotherapy has been shown to change the underlying allergic disease.

When determining if a patient needs sublingual immunotherapy, a doctor will often consider:

  • Severity. A person may be a candidate for sublingual allergy immunotherapy if their allergies are not just a passing annoyance but are severe enough to markedly affect their quality of life.
  • Duration. A person may be a candidate for sublingual immunotherapy if their allergies occur over at least three to four months of the year.

Once a patient has met the criteria for sublingual allergy immunotherapy, they can then decide whether allergy shots or allergy drops (sublingual immunotherapy) are a
better fit for their lifestyle.

1Rienzo VD, Minelli M, Musarra A, Sambugaro R, Pecora S, Canonica WG. “Post-marketing survey on the safety of sublingual immunotherapy in children below the age of 5 years.” Clinical and Experimental Allergy 2005, 35:560-4