COMPARE TREATMENTS
OIT vs SLIT: how the two food allergy treatments compare
OIT builds more tolerance
SLIT causes fewer serious reactions
Some patients choose both
Reviewed by Hunter Smith, MD · Last reviewed October 2026
IN SUMMARY
Oral immunotherapy builds higher tolerance. Sublingual immunotherapy causes fewer serious reactions and doesn't require rest periods or lifestyle restrictions.
Every study that has compared OIT and SLIT directly found OIT more effective at getting people to eat a full serving of the food. Every study that measured safety found SLIT caused fewer whole-body reactions.
The choice between OIT and SLIT is usually not about which is better, it is about which therapy works for a family or patient. OIT has more protection with more risk of side-effects and more clinic visits. SLIT may achieve less protection with fewer side-effects, fewer clinic visits, and minimal lifestyle changes.
Some patients choose both. Patients can start with SLIT and move to OIT later or choose SLIT for some of their food allergies while treating others with OIT.
Side by side comparison of SLIT and OIT
Topic
SLIT
OIT
How it is taken
A measured amount of food protein in a liquid, held under the tongue each day, then swallowed.
A measured amount of the food, as a powder or whole food, eaten each day.
Top dose
~4mg of protein daily
Variable: 300mg to 3,000 mg of protein daily
Clinic visits
Typically, four 30-min supervised office visits, one month apart, to double the amount of protein each time.
Typically, twelve, 1- to 2-hour supervised office visits, two weeks apart, to increase the amount of protein each time by 1.5 – 2x.
Restrictions
Few. Clinic visit may be required if dose is skipped for 3 or more days in a row.
Many. No strenuous activity before or after daily dose. No hot showers/baths before or after dose. No dosing if ill with a fever. No dosing on days of receiving a vaccine. Doctor supervision required after missed doses.
FDA approved for food allergy
Prescribed off-label.
Prescribed off-label. No approved peanut product since July 2026. No approved product for other allergies.
How much protection
Less. In studies most people reached a few hundred to a few thousand milligrams after 3 years of treatment.
More. Many people can eat a small amount of their allergen (about 1 peanut) after about 6-12 months of treatment. Some who finish 3 years of treatment can eat a full serving of their allergen (about 15 peanuts).
Side effects
Mostly mouth itching.
More frequent and more likely to involve the whole body. Stomach upset is common.
Serious reactions
Rare. In one head-to-head study about 11 times fewer whole-body reactions than OIT.
Common. Across 12 trials, anaphylaxis was about 3 times more common than avoiding the food.
Can protection last after stopping
Sometimes in very young children. Not well studied in older children or adults.
Sometimes, but many people lose it within weeks of stopping.
Evidence quality
Mostly peanut, small studies, low certainty ratings.
Strong. Many randomized trials. Mostly peanut.
How it is taken
SLIT
A measured amount of food protein in a liquid, held under the tongue each day, then swallowed.
OIT
A measured amount of the food, as a powder or whole food, eaten each day.
Top dose
SLIT
~4mg of protein daily
OIT
Variable: 300mg to 3,000 mg of protein daily
Clinic visits
SLIT
Typically, four 30-min supervised office visits, one month apart, to double the amount of protein each time.
OIT
Typically, twelve, 1- to 2-hour supervised office visits, two weeks apart, to increase the amount of protein each time by 1.5 – 2x.
Restrictions
SLIT
Few. Clinic visit may be required if dose is skipped for 3 or more days in a row.
OIT
Many. No strenuous activity before or after daily dose. No hot showers/baths before or after dose. No dosing if ill with a fever. No dosing on days of receiving a vaccine. Doctor supervision required after missed doses.
FDA approved for food allergy
SLIT
Prescribed off-label.
OIT
Prescribed off-label. No approved peanut product since July 2026. No approved product for other allergies.
How much protection
SLIT
Less. In studies most people reached a few hundred to a few thousand milligrams after 3 years of treatment.
OIT
More. Many people can eat a small amount of their allergen (about 1 peanut) after about 6-12 months of treatment. Some who finish 3 years of treatment can eat a full serving of their allergen (about 15 peanuts).
Side effects
SLIT
Mostly mouth itching.
OIT
More frequent and more likely to involve the whole body. Stomach upset is common.
Serious reactions
SLIT
Rare. In one head-to-head study about 11 times fewer whole-body reactions than OIT.
OIT
Common. Across 12 trials, anaphylaxis was about 3 times more common than avoiding the food.
Can protection last after stopping
SLIT
Sometimes in very young children. Not well studied in older children or adults.
OIT
Sometimes, but many people lose it within weeks of stopping.
Evidence quality
SLIT
Mostly peanut, small studies, low certainty ratings.
OIT
Strong. Many randomized trials. Mostly peanut.
Two other options exist: omalizumab (Xolair®), an injection that reduces reactions but doesn't retrain the immune system, and allergen avoidance.
What the head-to-head studies found
Only a few studies have compared SLIT and OIT in the same patients at the same time. They are small but show consistent findings.
Milk, 30 children (Keet 2012)
11×
more whole-body reactions with OIT
One of ten children who stayed on SLIT passed a full 8-gram milk challenge, compared with 14 of 20 who moved to OIT after a year of SLIT. But whole-body reactions were about 11 times more common with OIT, and rescue medicine was needed about 8 times more often.
Peanut, 21 children (Narisety 2015)
141× vs 22×
higher tolerance, OIT versus SLIT
Both treatments raised how much peanut children could tolerate. OIT raised it much further — about 141 times higher versus about 22 times higher than the patient's starting tolerance. But 43 of every 100 OIT doses caused some reaction (including mild itch), compared with 9 of every 100 SLIT doses. No child on SLIT needed epinephrine; four children on OIT did.
Doing both: SLIT first, then OIT
Some allergists use SLIT as a first step, then move to OIT. The idea is that the early part of OIT — where doses are increased at clinic visits — is the part families find hardest, and starting with SLIT may make it easier. Some patients may also find that SLIT helps ease their fear and anxiety about treatment.
In one report of 188 patients, a small number tried a low-dose food challenge, and 35 of those 50 challenges went well enough to start OIT at a 300 mg dose without the usual slow build-up. Note that this study followed patients only up to the point of starting OIT. It did not report how they did afterwards.
A consideration for families: while it is often said that most OIT reactions happen during build-up, a large meta-analysis of peanut OIT found the opposite. Reactions happened at a similar rate during build-up and during long-term maintenance. Patients who transition to OIT may still experience side-effects during their maintenance phase.
What to consider when choosing between OIT and SLIT
The end goal
Eating the food freely is more likely with OIT. Protection against an accidental bite is achievable with either.
Age
Under 4, SLIT has the best evidence for lasting protection after stopping. OIT also works well at this age.
The kind and severity of prior reactions
A person who has had severe reactions, or who has trouble with stomach symptoms, may do better with SLIT.
Time for office visits
OIT requires more, longer office. SLIT may be offered by telemedicine after the first visit.
Lifestyle
OIT requires a serious commitment. Missed doses or rushed doses without rest can significantly increase the risk of severe reactions.
Cost
Both SLIT and OIT are offered off-label. Insurance coverage will vary widely, and out-of-pocket costs can be up to $5,000 for a 3 year treatment for either SLIT or OIT.
What is not known
No large trial has compared SLIT and OIT directly. The head-to-head studies together include fewer than 60 patients.
Almost all SLIT and OIT research is on peanut.
Nobody knows how long protection lasts after stopping either treatment, and it may vary based on patient age, disease severity, and other factors.
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