1B20.20ICD-11 MMS 2026-01
Type I leprosy reaction
Description
This phenomenon, also named “upgrading reaction,” occurs in borderline leprosy states and is associated with an increase in cell-mediated immunity. It occurs typically within the first 6 months of treatment in previously untreated patients but may be related to stress, intercurrent infections, or pregnancy. Clinical features include inflammatory swelling, erythema and occasionally ulceration of existing lesions, constitutional symptoms and neuritis. If the neuritis is not treated promptly permanent motor nerve damage may ensue.
Index terms
- Type I leprosy reaction
- Leprosy reversal reaction
- Leprosy upgrading reaction
Exclusions from above levels
NE83.1– Infection arising from device, implant or graft, not elsewhere classified
Sibling codes
1B20.21– Type II leprosy reaction
Foundation entity
Type I leprosy reaction – http://id.who.int/icd/entity/1185467033
Allowed postcoordination axes
Part of: 1B20.2: Leprosy reactions › 1B20: Leprosy › 01: Certain infectious or parasitic diseases