Sublingual immunotherapy - SLIT - and subcutaneous immunotherapy - SCIT, the conventional allergy injection - are both forms of allergen immunotherapy, and they share the same fundamental mechanism: small, gradually increasing doses of the specific allergen are administered over time to shift the immune system from an allergic response toward tolerance. The difference is the route and the setting. SCIT requires injections given in a clinical setting - in my clinics this means attending for regular appointments during the build-up phase, followed by less frequent maintenance injections - with a waiting period after each injection to monitor for reactions. SLIT is administered as daily drops placed under the tongue and held there for one to two minutes before swallowing, or as dissolving tablets, and is taken at home rather than in clinic. The advantages of SLIT include the absence of injections (making it particularly well accepted by children and by adults who find clinic visits difficult to schedule regularly), and a strong safety profile that allows home administration without clinic supervision after the initial doses. The effectiveness of SLIT is strongest for house dust mite sensitisation, which is the most prevalent sensitisation in my Chennai patient population, and the evidence base is well established. SLIT does not produce instant symptom relief - it is a disease-modifying treatment over a three to five year period that reduces allergic reactivity and produces benefits that persist after the treatment course is completed.
Written by Dr. R. Arvind Kumar, MBBS, DNB Paediatrics, AASC (Advanced Allergy, Asthma and Clinical Immunology Specialist Course, 2026), Consultant Pediatrician and Child Specialist, NIRA Child Clinic, 68, 80 Feet Road, Thanikachalam Nagar, Kolathur, Chennai 600110 | Indiraa's Pediatric Clinic (now NIRA Child Clinic), No 62, Foxen Street, Amrithammal Colony, Perambur, Chennai 600011. 18+ years, 30,000+ patients. Phone: +91 9361409090 / 8608686704.
