“This is a safe and very effective therapy, which is probably underutilized within our own community.”

–  Dr. Susan Wasserman

Subcutaneous immunotherapy (SCIT) sits in that uncomfortable space between routine and risk. It’s one of the few interventions in allergy that can actually modify disease. But it also carries a small, very real risk of severe reactions. On this episode, Dr. Susan Wasserman, professor at McMaster University and a national leader in immunotherapy, walks through what safety really looks like in practice. And where things still go wrong.

On this episode, they discuss:

• Systemic reactions are uncommon but not rare
• Safety has improved through better patient selection, standardized extracts, and clinic preparedness
• Uncontrolled asthma is the most important risk factor for severe reactions
• Prior systemic reactions require reassessment, especially if the cause is correctable
• Build-up dosing carries higher risk than maintenance
• Rush and cluster protocols increase risk and need clear justification
• The 30-minute observation period captures most but not all reactions
• Beta blockers and ACE inhibitors may worsen reaction severity without increasing incidence

SCIT is one of the few tools we have that can actually change the trajectory of allergic disease. But it demands discipline. Careful screening. Reliable processes. And a team that’s ready to act when things go sideways.

Because most of the time, it’s safe.
And the rare times it isn’t—that’s where preparation matters most.

Posted on March 31, 2026.