Management of Type 1 Reversal Reaction in Leprosy Patients on Multidrug Therapy
Initiate oral prednisone 40-60 mg daily (or 0.5-1 mg/kg/day) immediately upon diagnosis of type 1 reversal reaction, continue multidrug therapy without interruption, and taper corticosteroids gradually over 12-20 weeks based on clinical response.
Recognition and Diagnosis
Type 1 reversal reaction manifests as acute inflammatory exacerbation of existing skin lesions (increased erythema, edema, scaling) and nerve trunk inflammation, occurring most commonly during the first year of multidrug therapy 1, 2. The reaction represents a shift toward enhanced cell-mediated immunity against mycobacterial antigens, with predominance of IFN-γ and IL-17 producing lymphocytes and diminished regulatory T-cell responses 3.
Key diagnostic features to identify:
- Skin changes: Pre-existing lesions become more erythematous, raised, and edematous; new lesions may appear; rarely progresses to erythroderma in severe cases 1, 3
- Nerve involvement: Acute neuritis with tenderness of nerve trunks (ulnar, median, radial, common peroneal, posterior tibial), new sensory loss, new motor weakness, or worsening of existing deficits 1, 4
- Timing: Most reactions occur during the first year of MDT (26.3% in BL patients, 12.8% in LL patients), with declining risk thereafter but reactions possible up to 4 years post-treatment 2
Immediate Management Protocol
Continue Multidrug Therapy
Do not stop dapsone, rifampicin, or clofazimine when type 1 reaction occurs 2, 4. The reaction is an immunological phenomenon, not drug toxicity, and interrupting antimicrobial treatment risks relapse and emergence of drug resistance.
Initiate Corticosteroid Therapy
Start oral prednisone 40-60 mg daily (or 0.5-1 mg/kg/day) immediately 4, 5. This dosage applies to all patients with:
- Any new nerve function impairment (sensory or motor loss)
- Nerve tenderness on palpation
- Severe skin inflammation threatening tissue integrity
- Facial or hand involvement with risk of deformity
Corticosteroid tapering schedule 4, 5:
- Maintain initial dose for 2-4 weeks until inflammation subsides
- Reduce by 5-10 mg every 2-4 weeks based on clinical response
- Total treatment duration typically 12-20 weeks
- Monitor for recurrence during taper; if symptoms return, increase dose to previous effective level
Assess and Monitor Nerve Function
Perform detailed nerve function testing at baseline and every 2-4 weeks 1, 2:
- Test sensation in hands and feet using monofilaments (2 g, 10 g)
- Assess motor function: thumb abduction, finger abduction, foot dorsiflexion, great toe extension
- Palpate nerve trunks for tenderness and thickening
- Document voluntary muscle testing scores
Prognosis for nerve recovery: 88.2% of patients treated promptly with prednisone achieve complete or partial recovery of nerve function; 11.8% show no improvement despite treatment 2. Early intervention within the first few weeks of nerve damage onset maximizes recovery potential.
Risk Stratification by Leprosy Classification
Borderline lepromatous (BL) patients: 43.6% develop reversal reaction within 2 years of starting MDT, with peak incidence in the first year (26.3%) 2
Lepromatous (LL) patients: 19.2% develop reversal reaction within 2 years, with 12.8% occurring in the first year 2
Borderline tuberculoid (BT) patients: 21.0% develop reversal reaction, with 10.3% during MDT and 7.3% in the first year after completing treatment 2
Distinguishing Type 1 from Type 2 Reaction
Type 1 reactions occur predominantly in borderline forms (BT, BB, BL) and involve pre-existing lesions becoming inflamed, whereas type 2 reactions (erythema nodosum leprosum) occur in lepromatous patients with new crops of painful nodules 1, 4. Type 2 reactions are far less common during MDT (2.7% in BL, 11.1% in LL) and are treated with thalidomide rather than corticosteroids alone 2, 4.
Critical Pitfalls to Avoid
Failing to initiate corticosteroids promptly when nerve involvement is present leads to irreversible disability 1, 5. The window for preventing permanent nerve damage is narrow—treatment must begin within days to weeks of symptom onset.
Stopping multidrug therapy during a reaction is unnecessary and harmful, as it does not address the immunological mechanism and risks treatment failure 2, 4.
Inadequate corticosteroid duration or too-rapid taper results in recurrent reactions requiring retreatment 5. Most patients require 12-20 weeks of therapy with gradual dose reduction.
Misdiagnosing late reversal reaction as relapse can occur when reactions develop months to years after completing MDT 2, 5. True relapse shows increasing bacterial index on skin smears, whereas late reactions show inflammatory changes without increased bacillary load.
Long-term Monitoring
Patients remain at risk for reversal reactions during MDT and for up to 4 years after treatment completion, though risk declines progressively over time 2. Educate patients to report immediately: new skin lesion inflammation, numbness, weakness, or nerve pain. Delayed reactions require the same aggressive corticosteroid approach as reactions occurring during active treatment 2, 5.