Lepra reactions

Authors: Dr Elise Ouedraogo, Dermatology Registrar, University Paris VI, Paris, France, Prof Pierre Couppie, Dermatologist, University Antilles-Guyane, French Guiana. DermNet NZ Editor in Chief, A/Prof Amanda Oakley, Dermatologist, Waikato Hospital, Hamilton, New Zealand. March 2017  

What is leprosy?

Leprosy is a bacterial infectious disease that mainly affects people in developing countries, including Brazil, Bangladesh, India, Democratic Republic of Congo and Nigeria.

  • In these regions, the annual incidence rate of leprosy is around 1/100 000 inhabitants, which is less than required to consider it an endemic disease.
  • Leprosy is caused by Mycobacterium leprae, which grows very slowly. It is usually transmitted through the air.
  • The classical clinical pattern of leprosy involves skin, nerves, nasal and oropharyngeal mucosa. It can lead to significant disability and stigmatisation. 
  • Curative treatment for the “indeterminate” stage includes rifampicin and dapsone; clofazimine is added for the multibacillary form of leprosy.
  • An immunological disorder can occur during the course of the disease, which is called a lepra reaction.
  • Lepra reactions mostly occur after treatment is started, but can also occur without treatment.

Type 1 lepra reaction

What is a type 1 lepra reaction?

The type 1 lepra reaction is a delayed type of hypersensitivity to M leprae antigens. It is also called a lepra 1 reaction.

  • The reaction most often occurs after treatment for leprosy has been started, but it may also occur before treatment and after the end of the treatment.
  • It reflects a strengthening of specific cellular immunity against M leprae towards the tuberculoid type.
Type 1 lepra reactions in borderline tuberculoid leprosy

Who gets type 1 lepra reaction?

The lepra 1 reaction is unpredictable. It occurs in patients with borderline disease, ie, the transition between tuberculoid leprosy (TTL) and lepromatous lepromatous leprosy (LLL). 

The classification of borderline leprosy includes:

  • Borderline tuberculoid leprosy (BTL)
  • Borderline borderline leprosy (BBL)
  • Borderline lepromatous leprosy (BLL).

What are the clinical features of type 1 lepra reaction?

Type 1 lepra reactions typically affect skin and nerves, and there are no systemic symptoms. The reaction is classified as mild or severe.

Skin signs 

  • Erythema and induration of existing lesions
  • Ulceration during very intense reactions.

Nerve involvement

  • Mainly affects cubital, sciatic, external popliteal, facial and cervical nerves
  • Often results in pain or tenderness 
  • Loss of function for more than a few days can cause muscle weakness,  loss of sensation, paralysis or deformity.

A mild type 1 lepra reaction is characterised by few inflamed plaques and no nerve impairment. A severe type 1 lepra reaction is characterised by many inflamed plaques and nerve impairment.

How is a type 1 lepra reaction diagnosed?

A type 1 lepra reaction is clinically suspected in a patient with borderline leprosy that develops symptoms within a few months of starting treatment. 

There are no routine laboratory tests. Skin biopsy may reveal:

  • Granulomas
  • Multinucleated giant cells
  • Oedema.

There is no increase of polymorphonuclear neutrophils in blood count or change in C-reactive protein (CRP) levels. Type 1 lepra reactions have been associated with elevated level of serum chemokine 10.

What is the treatment for a type 1 lepra reaction?

A mild lepra 1 reaction requires supportive care.

A severe lepra 1 reaction with nerve impairment requires prompt treatment.

  • First-line treatment is prednisone or prednisolone 0.5–1 mg/kg/day until inflammation has reduced, followed by a slowly tapering dose.
  • Ciclosporin is second-line treatment for severe type 1 reactions not controlled by prednisone.
  • Neurolysis or nerve surgery to relieve pressure may be necessary if nerve impairment persists.
  • Treatment with rifampicindapsone and/or clofazimine should continue.

What is the outcome of a type 1 lepra reaction?

The natural course of an untreated type 1 lepra reaction is for it to persist for several months.

  • The skin lesions continue to swell and may become confluent.
  • Nerve impairment can be very severe leading to loss of function and disability.

Type 2 lepra reaction

What is a type 2 lepra reaction?

A type 2 lepra reaction is characterised by an acute immune complex vasculitis affecting the skin and other organs. It is also called lepra 2 reaction, and is poorly understood. It is also called erythema nodosum leprosum.

Type 2 lepra reactions

Who gets type 2 lepra reaction?

The type 2 lepra reaction occurs in patients with:

  • Lepromatous lepromatous leprosy (LLL)
  • Borderline l­epromatous leprosy (BLL).

Lepra 2 is commonly associated with:

  • Puberty
  • Pregnancy
  • Lactation.

What are the clinical features of lepra type 2 reaction?

The clinical features of lepra 2 reactions depend on severity and which organs are affected.


  • Lesions are scattered on any part of the body, mainly on extensor aspect of the limbs and on the face
  • Multiple small red painful nodules
  • Sterile pustules and ulcers
  • May be superficial or deep in the dermis


  • Iridocyclitis: a red, painful eye


  • Orchitis: a swollen, red, painful testicle


  • Renal impairment or renal failure
  • Proteinuria


  • Cytolytic cholestasis


  • Fever
  • Fatigue
  • Enlarged lymph nodes
  • Swollen painful red joints

How is a type 2 lepra reaction diagnosed?

A type 2 lepra reaction is clinically suspected if a patient with lepromatous lepromatous or borderline lepromatous leprosy complains of fever and fatigue and has multiple painful red skin nodules, whether or not they have received treatment.

Blood tests show high inflammatory markers.

  • High white cell count
  • High protein C level
  • Sometimes,renal and liver impairment

Pathology is essential to confirm type 2 lepra reaction. A biopsy of a new red nodule less than 24 hours old shows:

  • An infiltrate of polymorphs superimposed on chronic inflammation
  • Heavy bacterial load of M leprae (special stains may be necessary).

What is the treatment for a type 2 lepra reaction?

Treatment depends on severity, assessed clinically and supported by laboratory tests.  A mild cutaneous reaction without other organ impairment can be managed by supportive care:

  • Painkillers
  • Control of fever
  • Regular monitoring.

Treatment for severe lepra 2 reactions may include:

  • Prednisone at a dose of about 1 mg/kg/day, quickly tapered
  • Clofazimine: note that the multibacillary (MB) regimen with clofazimine prevents type 2 reactions
  • Thalidomide 400 mg/day for 5 to 10 days, tapered over 1 to 2 months.

Ciclosporin, azathioprine, methotrexate, mycophenolate mofetil and pentoxifylline have been used successfully in small trials.

What is the outcome of a type 2 lepra reaction?

Without treatment, lepra 2 reactions continue for about 2 weeks then settle down. Recurrences are frequent.

Untreated type 2 lepra reactions can result in renal failure requiring dialysis, liver failure requiring transplantation, blindness, and/or long-term inflammation of the testicles.

Lucio phenomenon

Lucio phenomenon is a very rare, acute and severe complication of longstanding and untreated lepromatous lepromatous leprosy. It may be life threatening.

  • It mainly occurs in patients with Mexican ancestry.
  • It presents with multiple punched-out and necrotic ulcers.

Lucio phenomenon is treated intensively with systemic steroids

Leg ulceration due to Lucio phenomenon in leprosy


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