The standard treatment for GPA is cyclophosphamide and high dose corticosteroids for remission induction and less toxic immunosuppressants like azathioprine, leflunomide, methotrexate or mycophenolate mofetil. Trimethoprim/sulfamethoxazole may also help prevent relapse. Rituximab may be substituted for cyclophosphamide in inducing remission.

A systematic review of 84 trials examined the evidence for various treatments in GPA. Many trials include data on pooled groups of people with GPA and microscopic polyangiitis. In this review, cases are divided between localised disease, non-organ threatening, generalized organ-threatening disease and severe kidney vasculitis and immediately life-threatening disease.

- In generalised non-organ-threatening disease, remission can be induced with methotrexate and steroids, where the steroid dose is reduced after a remission has been achieved and methotrexate used as maintenance.

- In case of organ-threatening disease, pulsed intravenous cyclophosphamide with steroids is recommended. Once remission has been achieved, azathioprine and steroids can be used to maintain remission.

- In severe kidney vasculitis, the same regimen is used but with the addition of plasma exchange.

- In pulmonary haemorrhage, high doses of cyclophosphamide with pulsed methylprednisolone may be used, or alternatively CYC, steroids, and plasma exchange.

Therapy for GPA and MPA has two main components: induction of remission with initial immunosuppressive therapy, and maintenance of remission with immunosuppressive therapy for a variable period to prevent relapse.

The mainstay of treatment for granulomatosis with polyangiitis (GPA) is a combination of corticosteroids and cytotoxic agents.

- Medications

- Side effect treatments

- Plasma exchange

- Kidney transplant

Before modern treatments, the 2-year mortality was over 90% and average survival five months. Death usually resulted from uremia or respiratory failure.

With corticosteroids and cyclophosphamide, 5-year survival is over 80%. Long-term complications are common (86%), mainly chronic kidney failure, hearing loss and deafness.

Today, drug toxicity is managed more carefully and long-term remissions are possible. Some patients are able to lead relatively normal lives and remain in remission for 20+ years after treatment.