Table 2. Distinguishing Features of Type 1 and Type 2 Leprosy Reactions.

Leprosy Stage	Type 1 Reaction–Reversal Reaction (RR)	Type 2 Reaction–Erythema Nodosum Leprosum (ENL)
	Occurs in borderline disease (BT, BB, BL)a	Occurs in BL and LLa
Skin	Acute onset of redness and swelling in leprosy skin lesions and sometimes lesions may ulcerate. Marked edema of the hands, feet, and face may occur. No new lesions appear.	New painful and tender red papules or nodules which occur in crops in limbs or trunk and face. Ulceration of nodules may occur. Edema of the hands, feet, or face may occur. Original leprosy skin patches remain as they were.
Nerve	New nerve damage manifesting as numbness, or muscle weakness in the hands, feet, or face. Pain or tenderness in one or more nerves, with or without loss of nerve function.b	New nerve damage manifesting as numbness, or muscle weakness in the hands, feet, or face. Pain or tenderness in one or more nerves, with or without loss of nerve function.
Systemic	Unusual	Common, including fever, malaise; lymphadenitis, uveitis, neuritis, arthritis, dactylitis, orchitis.
Diagnosis	Clinicalc	Clinicald
Treatment	Steroidse	Steroids

^aBT  =  borderline tuberculoid; BB = borderline borderline; BL = borderline lepromatous; LL = lepromatous.

^bSometimes silent neuritis may be present, manifested by nerve function impairment (loss of sensations and/or muscle weakness) without skin inflammation.

^cSkin biopsy may present some key features such as dermal edema, granuloma edema, and presence of giant cells and plasma cells.

^dSkin biopsy may present a mixed dermal infiltrate of neutrophils and lymphocytes and fragmented bacilli in macrophages.

^eFor mild reactions, non-steroidal anti-inflammatory drugs may be sufficient. Prednisone or prednisolone are used for severe signs and symptoms; for alternative treatment options, see Table 2.