Barriers to Using SLIT, With Désirée Larenas-Linnemann, MD

At the 2026 American Academy of Allergy, Asthma & Immunology (AAAAI) annual meeting in Philadelphia, Désirée Larenas-Linnemann, MD, from Hospital Médica Sur, shared persistent real‑world barriers to broader adoption of sublingual immunotherapy (SLIT) in the United States. Although SLIT can offer a home‑based alternative to injections, financial and practical hurdles continue to limit its uptake.

“It’s only one allergen that you can give in a tablet,” Larenas-Linnemann said. “If you want to do 2 allergens, you have to give 2 tablets, which doubles the cost. Most tablets are not covered by insurance.”

She further emphasized the complexity of prescribing tablets for allergic asthma, as not all formulations have FDA approval for this indication. However, since many patients also have concomitant allergic rhinitis, clinicians often navigate this off-label use.

Adherence is another critical factor. Larenas-Linnemann described wide variability among patients, observing that while some strictly follow daily dosing, others stretch vials beyond recommended intervals, undermining therapeutic effectiveness.

“If you really want to have good effects, you need to have your monthly dose,” she said. “You need to have your daily dose, ideally, with the tablets.”

Emerging research on multi-allergen SLIT, particularly in liquid form, may expand treatment options, though evidence remains limited. Larenas-Linnemann said it could be possible to use 2 tablets for multi-allergen therapy, but evidence is scarce. European guidelines suggest a 30-minute interval, but this is based on a single study, and the effect of administering 2 tablets simultaneously remains unknown.

“It's a recommendation without solid evidence behind it,” Larenas-Linnemann said.

When it comes to multi‑allergen SLIT, Larenas‑Linnemann emphasized careful patient selection. Typical combinations might include grass pollen, tree pollen, cat dander, and house dust mite. Clinicians must ensure the patient is clinically reactive to these allergens, as positive skin tests alone do not always reflect current symptomatic allergy. For example, patients may test positive for mold exposure they encountered years ago but no longer experience symptoms in their current environment, making immunotherapy unnecessary for that allergen.

Evidence for multi‑allergen liquid SLIT remains limited but promising. Studies combining 2 allergens, such as house dust mite and grass pollen, have demonstrated efficacy over 1 to 2 years. Trials mixing 3 or 4 allergens show weaker but still observable responses, and even studies attempting 10-allergen combinations suggest a signal of benefit when focusing on relevant allergens. Larenas‑Linnemann noted that statistical significance may be limited by small sample sizes.

In her practice, she limits multi‑allergen therapy to no more than four allergens, using liquid formulations with high concentrations to maximize the potential therapeutic effect. The goal is to deliver the strongest possible dose for each relevant allergen, balancing efficacy with safety.

Larenas-Linnemann has no relevant disclosures.

References

Larenas-Linnemann, D. What Should You Know About SLIT in 2026? Session presented at the American Academy of Allergy, Asthma, & Immunology (AAAAI) in Philadelphia on February 28, 2026.