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Frequently Asked Questions About Food Sublingual Immunotherapy

What is sublingual immunotherapy?

Sublingual immunotherapy (SLIT) is a form of immunotherapy that involves putting a liquid form of the food your allergic to under the tongue. Many people refer to this process as “allergy drops,” and it is an alternative treatment to oral immunotherapy (OIT). SLIT is delivered under the tongue, held there for two minutes, and then swallowed. SLIT has been used in patients with airborne allergies (hay fever and asthma) for many years in Europe, and has recently gained some interest in the United States. A few SLIT environmental allergens (dust mites, grass, and ragweed) have been approved by the US Food and Drug Administration (FDA), but none for food allergy.

How does SLIT work?

Food proteins placed under the tongue, come in contact with oral mucus membranes that then interact with special immune cells called dendritic cells. These cells communicate with other immune cells (T lymphocytes) to hyposensitize you, or reduce your allergies. 

What kind of allergies can be treated with SLIT?

The same kind of food allergies we’ve been treating with OIT, i.e. peanut, tree nuts, egg, milk, wheat and sesame.

Is SLIT safe?

Over the past 20 years, the safety of SLIT has been well documented. Fatal reactions to SLIT have not been reported to date, and serious reactions are extremely rare. Mild side effects, such as an itchy mouth, occur in the majority of people initially and tend to resolve over time.

Moderate side effects have been documented (1 in about every 12,000 doses), including: eye itching, nausea, vomiting, diarrhea, asthma symptoms and hives.

SLIT has a very good safety profile, largely because the oral mucosa is conditioned to tolerate various proteins on a daily basis, such as foods and resident bacteria. As a result, the sublingual mucosa has few pro-inflammatory cells, such as mast cells (which trigger allergic reactions in the skin, nose and lungs). This helps to explain why SLIT, when compared to OIT, is less likely to cause a severe, generalized allergic reaction.

Who could (or should) receive SLIT?

At the present time, food OIT is a popular method of treatment, but the ease and safety of SLIT makes it an attractive alternative, especially in the highly allergic person, particularly teens and older, or someone who has struggled with OIT.

What are the advantages of SLIT compared to OIT?

SLIT has been shown to produce fewer adverse reactions than OIT. The drops have a sweet taste since the food is diluted in glycerin. Some patients have taste aversion with OIT since they are consuming the very food that not only caused a reaction in the past, but also the one they have been told and conditioned to avoid for many years. This can become a difficult psychological hurdle for some people.

What are the disadvantages of SLIT compared to OIT?

SLIT will make you safe from accidental exposure to the food you’re allergic to, but often does not allow free-eating of the food. Some patients will transition from SLIT after 1-2 years to OIT so they can reach the higher, protective amount of food.

Why is SLIT not yet FDA approved?

The drops are a food, not a drug, so approval is only necessary if a company wanted to market a specific, proprietary product. A trial is being done with a peanut product under the tongue. There is a peanut capsule approved by the FDA for OIT and work is being done with foods delivered via a skin patch.

How is SLIT taken?

Liquid food is self-administered at home, under the tongue. The early doses of the food are prepared here in the office and given to you from a plastic bottle. You will use a small syringe to draw up a very small amount (less than 1/10th of a tsp) and squirt it under the tongue. The liquid is held under the tongue for approximately two minutes before being swallowed. If you are on more than one food, the 2nd food can be taken two minutes after the 1st. We ask that you don’t eat or drink for five minutes after dosing. In general, children have to be at least five years old to be able to cooperate with the procedure. There will be ~4 updose visits until you reach your maintenance dose. At each updose visit you will receive a series of 2-3 low doses 20 minutes apart, then repeat the top dose at home daily until the next updose visit in 1-2 weeks. For foods that are available in a convenient liquid form, milk, egg white liquid, and tree nut milks, the maintenance dose uses undiluted food from your local grocery. Other foods commonly used in SLIT, peanut, sesame and wheat, use diluted flour that we’ll provide to you in bottles good for 3-6 months.

How long do I have to wait after taking SLIT before eating and being active?

Typically, we ask patients to wait at least five minutes before eating or drinking, just to allow for additional absorption time for the drops. Unlike OIT, there is no rest period before or after dosing with SLIT. We tested a dozen patients on an exercise bike with dosing immediately after exercise, followed by more exercise post-dose: they all did great!

Can I travel with SLIT?

Yes.  They are very easy to travel with and can go anywhere you go. The plastic bottles have a small enough volume to be carried through airport security. Since taking the dose requires only a few minutes out of your day, it is very easy to continue your treatment no matter where you are, or how long you’re away.

Does SLIT need to be refrigerated?

Yes. Remember, several foods are store bought milks. The diluted flours also do better when refrigerated.

Does my insurance cover SLIT?

The food is being introduced in a series of doses at each visit. This is considered a food challenge and, as such, is covered by insurance.  There is an upfront startup fee for this novel form of food therapy. The front office can review all charges with you prior to starting SLIT.