Treatment is targeted to the underlying cause. However, most vasculitis in general are treated with steroids (e.g. methylprednisolone) because the underlying cause of the vasculitis is due to hyperactive immunological damage. Immunosuppressants such as cyclophosphamide and azathioprine may also be given.

A systematic review of antineutrophil cytoplasmic antibody (ANCA) positive vasculitis identified best treatments depending on whether the goal is to induce remission or maintenance and depending on severity of the vasculitis.

Treatments are generally directed toward stopping the inflammation and suppressing the immune system. Typically, corticosteroids such as prednisone are used. Additionally, other immune suppression drugs, such as cyclophosphamide and others, are considered. In case of an infection, antimicrobial agents including cephalexin may be prescribed. Affected organs (such as the heart or lungs) may require specific medical treatment intended to improve their function during the active phase of the disease.

The customary treatment involves long term dosage of prednisone, alternated or combined with cytotoxic drugs, such as cyclophosphamide or azathioprine.

Plasmapheresis may also be indicated in the acute setting to remove ANCA antibodies.

Rituximab has been investigated, and in April 2011 approved by the FDA when used in combination with glucocorticoids in adult patients.

Treatment for eosinophilic granulomatosis with polyangiitis includes glucocorticoids (such as prednisolone) and other immunosuppressive drugs (such as azathioprine and cyclophosphamide). In many cases, the disease can be put into a type of chemical remission through drug therapy, but the disease is chronic and lifelong.

A systematic review conducted in 2007 indicated all patients should be treated with high-dose steroids, but in patients with a five-factor score of one or higher, cyclophosphamide pulse therapy should be commenced, with 12 pulses leading to fewer relapses than six. Remission can be maintained with a less toxic drug, such as azathioprine or methotrexate.

On December 12, 2017, the FDA approved mepolizumab, the first drug therapy specifically indicated for the treatment of eosinophilic granulomatosis with polyangiitis. Patients taking mepolizumab experienced a "significant improvement" in their symptoms.

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.

Treatment should be directed towards the specific underlying cause of the vasculitis. If no underlying cause is found and the vasculitis is truly limited to the skin then treatment is primarily supportive. Such treatment involves measures such as leg elevation, stockings, and topical steroids to relieve itching/burning. If the vasculitis does not self-resolve within 3–4 weeks, more aggressive treatment may be warranted. Oral colchicine or dapsone are often used for this purpose. If rapid control of symptoms is needed, a short course of high-dose oral steroids may be given. Immunosuppressive agents such as methotrexate and azathioprine may be used in truly refractory cases not responsive to colchicine or dapsone.

Vasculitis secondary to connective tissue disorders. Usually secondary to systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), relapsing polychondritis, Behçet's disease, and other connective tissue disorders.

Vasculitis secondary to viral infection. Usually due to hepatitis B and C, HIV, cytomegalovirus, Epstein-Barr virus, and Parvo B19 virus.

Microscopic polyangiitis is an ill-defined autoimmune disease characterized by a systemic, pauci-immune, necrotizing, small-vessel vasculitis without clinical or pathological evidence of necrotizing granulomatous inflammation.

Treatment involves medications to suppress the immune system, including prednisone and cyclophosphamide. In some cases, methotrexate or leflunomide may be helpful. Some patients have also noticed a remission phase when a four-dose infusion of rituximab is used before the leflunomide treatment is begun. Therapy results in remissions or cures in 90% of cases. Untreated, the disease is fatal in most cases. The most serious associated conditions generally involve the kidneys and gastrointestinal tract. A fatal course usually involves gastrointestinal bleeding, infection, myocardial infarction, and/or kidney failure.

In case of remission, about 60% experience relapse within five years. In cases caused by hepatitis B virus, however, recurrence rate is only around 6%.

Case studies of individuals with HUV have also highlighted other potential complicating factors which it seems the anti-C1q antibodies play a role in. This can mean in some cases the deposition of large immune complexes in the kidney which cannot be cleared by the usual cells of the immune system (e.g. macrophages which are unable to bind the Fc portion of the C1q antibody), leading to further complications. This it seems is rare, but can occur when a pre-existing renal condition is apparent. Also, there has been some speculation as to an additional autoantibody against an inhibitor protein (in the complement pathway) named C1-inhibitor. The inhibition of C1-inhibitor leads to over-activation of the complement pathway and one protein that builds up controls angioedema (vessel – swelling), resulting in excess water building up under the skin (the weal appearance).

Unfortunately there are no known specific therapies for HUV. The regime of prescription steroids and other immunosuppressive drugs aims to dampen the body's production of anti-C1q antibodies. However, this again renders the individual immunocompromised.

Vasculitis is a group of disorders that destroy blood vessels by inflammation. Both arteries and veins are affected. Lymphangitis is sometimes considered a type of vasculitis. Vasculitis is primarily caused by leukocyte migration and resultant damage.

Although both occur in vasculitis, inflammation of veins (phlebitis) or arteries (arteritis) are their own are separate entities.

Antibodies are usually raised against foreign proteins, such as those made by a replicating virus or invading bacterium. Virus or bacteria with antibodies opsonized or "stuck" to them highlight them to other cells of the immune system for clearance.

Antibodies against self proteins are known as autoantibodies, and are not found in healthy individuals. These autoantibodies can be used to detect certain diseases.

Treatment of mixed cryoglobulinemic disease is, similar to type I disease, directed toward treating any underlying disorder. This includes malignant (particularly Waldenström's macroglobulinemia in type II disease), infectious, or autoimmune diseases in type II and III disease. Recently, evidence of hepatitis C infection has been reported in the majority of mixed disease cases with rates being 70-90% in areas with high incidences of hepatitis C. The most effective therapy for hepatitis C-associated cryoglobulinemic disease consists of a combination of anti-viral drugs, pegylated INFα and ribavirin; depletion of B cells using rituximab in combination with antiviral therapy or used alone in patients refractory to antiviral therapy has also proven successful in treating the hepatitis C-associated disease. Data on the treatment of infectious causes other than hepatitis C for the mixed disease are limited. A current recommendation treats the underlying disease with appropriate antiviral, anti-bacterial, or anti-fungal agents, if available; in cases refractory to an appropriate drug, the addition of immunosuppressive drugs to the therapeutic regimen may improve results. Mixed cryoglobulinemic disease associated with autoimmune disorders is treated with immunosuppressive drugs: combination of a corticosteroid with either cyclophosphamide, azathioprine, or mycophenolate or combination of a corticosteroid with rituximab have been used successfully to treated mixed disease associated with autoimmune disorders.

Eosinophilic granulomatosis with polyangiitis (EGPA; also known as Churg-Strauss syndrome [CSS] or allergic granulomatosis) is an extremely rare autoimmune condition that causes inflammation of small and medium-sized blood vessels (vasculitis) in persons with a history of airway allergic hypersensitivity (atopy).

It usually manifests in three stages. The early (prodromal) stage is marked by airway inflammation; almost all patients experience asthma and/or allergic rhinitis. The second stage is characterized by abnormally high numbers of eosinophils (hypereosinophilia), which causes tissue damage, most commonly to the lungs and the digestive tract. The third stage consists of vasculitis, which can eventually lead to cell death and can be life-threatening.

This condition is now called "eosinophilic granulomatosis with polyangiitis" to remove all eponyms from the vasculitides. To facilitate the transition, it was referred to as "eosinophilic granulomatosis with polyangiitis (Churg-Strauss)" for a period of time starting in 2012. Prior to this it was known as "Churg-Strauss syndrome", named after Drs. Jacob Churg and Lotte Strauss who, in 1951, first published about the syndrome using the term "allergic granulomatosis" to describe it. It is a type of systemic necrotizing vasculitis.

Effective treatment of EGPA requires suppression of the immune system with medication. This is typically glucocorticoids, followed by other agents such as cyclophosphamide or azathioprine.

All patients with symptomatic cryoglobulinemia are advised to avoid, or protect their extremities, from exposure to cold temperatures. Refrigerators, freezers, and air-conditioning represent dangers of such exposure.

Cutaneous small-vessel vasculitis, also known as hypersensitivity vasculitis, cutaneous leukocytoclastic vasculitis, hypersensitivity angiitis, cutaneous leukocytoclastic angiitis, cutaneous necrotizing vasculitis and cutaneous necrotizing venulitis, is inflammation of small blood vessels (usually post-capillary venules in the dermis), characterized by palpable purpura. It is the most common vasculitis seen in clinical practice.

"Leukocytoclastic" refers to the damage caused by nuclear debris from infiltrating neutrophils in and around the vessels.

The condition affects adults more frequently than children and males more frequently than females. Most cases occur between the ages of 30 and 49. It damages the tissues supplied by the affected arteries because they do not receive enough oxygen and nourishment without a proper blood supply. Polyarteritis nodosa is more common in people with hepatitis B infection.

Analgesics may be needed for the abdominal and joint pains. It is uncertain as to whether HSP needs treatment beyond controlling the symptoms. Most patients do not receive therapy because of the high spontaneous recovery rate. Steroids are generally avoided. However, if they are given early in the disease episode, the duration of symptoms may be shortened, and abdominal pain can improve significantly. Moreover, the chance of severe kidney problems may be reduced. A systematic review of randomized clinical trials did not find any evidence that steroid treatment (prednisone) is effective at decreasing the likelihood of developing long-term kidney disease.

Evidence of worsening kidney damage would normally prompt a kidney biopsy. Treatment may be indicated on the basis of the appearance of the biopsy sample; various treatments may be used, ranging from oral steroids to a combination of intravenous methylprednisolone (steroid), cyclophosphamide and dipyridamole followed by prednisone. Other regimens include steroids/azathioprine, and steroids/cyclophosphamide (with or without heparin and warfarin). Intravenous immunoglobulin (IVIG) is occasionally used.

There is no evidence from randomized clinical trials that treating children who have HSP with antiplatelet agent prevents persistent kidney disease. There is also no evidence from randomized clinical trials that treating children or adults with cyclophosphamide prevents severe kidney disease. Heparin treatment is not justified.

Current treatment is aimed at easing the symptoms, reducing inflammation, and controlling the immune system. The quality of the evidence for treating the oral ulcers associated with Behçet's disease, however, is poor.

High-dose corticosteroid therapy is often used for severe disease manifestations. Anti-TNF therapy such as infliximab has shown promise in treating the uveitis associated with the disease. Another Anti-TNF agent, etanercept, may be useful in people with mainly skin and mucosal symptoms.

Interferon alpha-2a may also be an effective alternative treatment, particularly for the genital and oral ulcers as well as ocular lesions. Azathioprine, when used in combination with interferon alpha-2b also shows promise, and colchicine can be useful for treating some genital ulcers, erythema nodosum, and arthritis.

Thalidomide has also been used due to its immune-modifying effect. Dapsone and rebamipide have been shown, in small studies, to have beneficial results for mucocutaneous lesions.

Given its rarity, the optimal treatment for acute optic neuropathy in Behçet's disease has not been established. Early identification and treatment is essential. Response to ciclosporin, periocular triamcinolone, and IV methylprednisone followed by oral prednisone has been reported although relapses leading to irreversible visual loss may occur even with treatment. Immunosuppressants such as interferon alpha and tumour necrosis factor antagonists may improve though not completely reverse symptoms of ocular Behçet's disease, which may progress over time despite treatment. When symptoms are limited to the anterior chamber of the eye prognosis is improved. Posterior involvement, particularly optic nerve involvement, is a poor prognostic indicator. Secondary optic nerve atrophy is frequently irreversible. Lumbar puncture or surgical treatment may be required to prevent optic atrophy in cases of intracranial hypertension refractory to treatment with immunomodulators and steroids.

IVIG could be a treatment for severe or complicated cases.

Once a diagnosis of JDMS is made, the treatment is often a 3-day course of Intravenous ("pulse") steroids (methylprednisolone, Solu-Medrol), followed by a high dose of oral prednisone (usually 1–2 mg/kg of body weight) for several weeks. This action usually brings the disease under control, lowering most lab tests to or near normal values. Some minor improvement in muscle symptoms may also be seen in this time, but normally it takes a long time for full muscle strength to be regained.

Once the disease process is under control, oral steroids are tapered gradually to minimize their side effects. Often, steroid-sparing drugs, such as methotrexate (a chemotherapy drug) or other DMARDs, are given to compensate for the reduction in oral steroids. Once the oral steroids are reduced to a less toxic level, the sparing agents can also be gradually withdrawn. Lab results are closely monitored during the tapering process to ensure that the disease does not recur.

In the cases where steroids or second-line drugs are not tolerated or are ineffective, there are other treatments that can be tried. These include other chemotherapy drugs, such as ciclosporin, infliximab, or other DMARDs. Another is intravenous immunoglobulin (IVIg), a blood product that has been shown to be very effective against JDMS.

To treat the skin rash, anti-malarial drugs, such as hydroxychloroquine (Plaquenil) are usually given. Topical steroid creams (hydrocortisone) may help some patients, and anti-inflammatory creams (such as tacrolimus) are proving to be very effective. Dry skin caused by the rash can be combated by regular application of sunscreen or any moisturizing cream. Most JDM patients are very sensitive to sun exposure, and sunburn may be a disease activity trigger in some, so daily application of high-SPF sunscreen is often recommended.

Of the children diagnosed with and treated for JDM, about half will recover completely. Close to 30 percent will have weakness after the disease resolves. Most children will go into remission and have their medications eliminated within two years, while others may take longer to respond or have more severe symptoms that take longer to clear up.

A common lasting effect of JDM is childhood arthritis.

HSP occurs more often in children than in adults, and usually follows an upper respiratory tract infection. Half of affected patients are below the age of six, and 90% are under ten. It occurs about twice as often in boys as in girls. The incidence of HSP in children is about 20 per 100,000 children per year, making it the most common vasculitis in children.

Cases of HSP may occur anytime throughout the year, but some studies have found that fewer cases occur during the summer months.

Children with Kawasaki disease should be hospitalized and cared for by a physician who has experience with this disease. When in an academic medical center, care is often shared between pediatric cardiology, pediatric rheumatology, and pediatric infectious disease specialists (although no specific infectious agent has been identified as yet). Treatment should be started as soon as the diagnosis is made to prevent damage to the coronary arteries.

Intravenous immunoglobulin (IVIG) is the standard treatment for Kawasaki disease and is administered in high doses with marked improvement usually noted within 24 hours. If the fever does not respond, an additional dose may have to be considered. In rare cases, a third dose may be given to the child. IVIG by itself is most useful within the first seven days of onset of fever, in terms of preventing coronary artery aneurysm.

Salicylate therapy, particularly aspirin, remains an important part of the treatment (though questioned by some) but salicylates alone are not as effective as IVIG. Aspirin therapy is started at high doses until the fever subsides, and then is continued at a low dose when the patient returns home, usually for two months to prevent blood clots from forming. Except for Kawasaki disease and a few other indications, aspirin is otherwise normally not recommended for children due to its association with Reye's syndrome. Because children with Kawasaki disease will be taking aspirin for up to several months, vaccination against varicella and influenza is required, as these infections are most likely to cause Reye's syndrome.

High-dose aspirin is associated with anemia and does not confer benefit to disease outcomes.

Corticosteroids have also been used, especially when other treatments fail or symptoms recur, but in a randomized controlled trial, the addition of corticosteroid to immune globulin and aspirin did not improve outcome. Additionally, corticosteroid use in the setting of Kawasaki disease is associated with increased risk of coronary artery aneurysm, so its use is generally contraindicated in this setting. In cases of Kawasaki disease refractory to IVIG, cyclophosphamide and plasma exchange have been investigated as possible treatments, with variable outcomes.

Surgical treatment of arterial manifestations of BD bears many pitfalls, since the obliterative endarteritis of vasa vasorum causes thickening of the medial layer and splitting of elastin fibers. Therefore, anastomotic pseudoaneurysms are likely to form, as well as pseudoaneurysms at the site of puncture in case of angiography or endovascular treatment; furthermore, early graft occlusion may occur.

For these reasons, invasive treatment should not be performed in the acute and active phases of the disease when inflammation is at its peak. The evaluation of disease’s activity is usually based on relapsing symptoms, ESR (erythrocyte sedimentation rate), and serum levels of CRP (C‐reactive protein).

Endovascular treatment can be an effective and safe alternative to open surgery, with less postoperative complications, faster recovery time, and reduced need for intensive care, while offering patency rates and procedural success rates comparable with those of surgery. This notwithstanding, long‐term results of endovascular treatment in BD are still to be determined.