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.

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.

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.

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

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.

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.

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.

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.

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.

People affected by the severest, often life-threatening, complications of cryoglobulinemic disease require urgent plasmapharesis and/or plasma exchange in order to rapidly reduce the circulating levels of their cryoglobulins. Complications commonly requiring this intervention include: hyperviscosity disease with severe symptoms of neurological (e.g. stroke, mental impairment, and myelitis) and/or cardiovascular (e.g., congestive heart failure, myocardial infarction) disturbances; vasculitis-driven intestinal ischemia, intestinal perforation, cholecystitis, or pancreatitis, causing acute abdominal pain, general malaise, fever, and/or bloody bowel movements; vasculitis-driven pulmonary disturbances (e.g. coughing up blood, acute respiratory failure, X-ray evidence of diffuse pulmonary infiltrates caused by diffuse alveolar hemorrhage); and severe kidney dysfunction due to intravascular deposition of immunoglobulins or vasculitis. Along with this urgent treatment, severely symptomatic patients are commonly started on therapy to treat any underlying disease; this treatment is often supplemented with anti-inflammatory drugs such as corticosteroids (e.g., dexamethasone) and/or immunosuppressive drugs. Cases where no underlying disease is known are also often treated with the latter corticosteroid and immunosuppressive medications.

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%.

Most people with Takayasu’s arteritis respond to steroids such as prednisone. The usual starting dose is approximately 1 milligram per kilogram of body weight per day (for most people, this is approximately 60 milligrams a day). Because of the significant side effects of long-term high-dose prednisone use, the starting dose is tapered over several weeks to a dose which controls symptoms while limiting the side effects of steroids.

Promising results are achieved with mycophenolate and tocilizumab. If treatment is not kept to a high standard, long-term damage or death can occur.

For patients who do not respond to steroids may require revascularization, either via vascular bypass or angioplasty and stenting. Outcomes following revascularization vary depending on the severity of the underlying disease

The culprit can be both a prescription drug or an over-the-counter medication.

Examples of common drugs causing drug eruptions are antibiotics and other antimicrobial drugs, sulfa drugs, nonsteroidal anti-inflammatory drugs (NSAIDs), biopharmaceuticals, chemotherapy agents, anticonvulsants, and psychotropic drugs. Common examples include photodermatitis due to local NSAIDs (such as piroxicam) or due to antibiotics (such as minocycline), fixed drug eruption due to acetaminophen or NSAIDs (Ibuprofen), and the rash following ampicillin in cases of mononucleosis.

Certain drugs are less likely to cause drug eruptions (rates estimated to be ≤3 per 1000 patients exposed). These include: digoxin, aluminum hydroxide, multivitamins, acetaminophen, bisacodyl, aspirin, thiamine, prednisone, atropine, codeine, hydrochlorothiazide, morphine, insulin, warfarin, and spironolactone.

The preferred treatment for many patients is desensitization to aspirin, undertaken at a clinic or hospital specializing in such treatment. In the United States, the Scripps Clinic in San Diego, CA, the Massachusetts General Hospital in Boston, MA, the Brigham and Women's Hospital in Boston, MA, National Jewish Hospital in Denver and Stanford University Adult ENT Clinic have allergists who routinely perform aspirin desensitization procedures for patients with aspirin-induced asthma. Patients who are desensitized then take a maintenance dose of aspirin daily and while on daily aspirin they often have reduced need for supporting medications, fewer asthma and sinusitis symptoms than previously, and many have an improved sense of smell. Desensitization to aspirin reduces the chance of nasal polyp recurrence, and can slow the regrowth of nasal polyps. Even patients desensitized to aspirin may continue to need other medications including nasal steroids, inhaled steroids, and leukotriene antagonists.

Leukotriene antagonists and inhibitors (montelukast, zafirlukast, and zileuton) are often helpful in treating the symptoms of aspirin-induced asthma. Some patients require oral steroids to alleviate asthma and congestion, and most patients will have recurring or chronic sinusitis due to the nasal inflammation.

Treatment of secondary cryofibrinoginemic disease may use the same methods used for treating the primary disease wherever necessary but focus on treating the associated infectious, malignant, premalignant, vasculitis, or autoimmune disorder with the methods prescribed for the associated disorder. Case report studies suggest that: corticosteroids and immunosuppressive drug regimens, antimicrobial therapy, and anti-neoplastic regimens can be effective treatments for controlling the cryfibrinoginemic disease in cases associated respectively with autoimmune, infectious, and premalignant/malignant disorders.

Studies on the treatment of cryofibrinoginemic disease have involved relatively few patients, are limited primarily to case reports, and differ based on whether the disease is primary or secondary. In all cases of cryofibrinogenemic disease, however, patients should avoid the exposure of afflicted body parts to cold weather or other environmental triggers of symptoms and avoid using cigarettes or other tobacco products. In severe cases, these individuals also risk developing serious thrombotic events which lead to tissue necrosis that may result in secondary bacterial infections and require intensive antimicrobial therapy and/or amputations. Careful treatment of these developments is required.

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.

Often surgery is required to remove nasal polyps, although they typically recur, particularly if aspirin desensitization is not undertaken. 90% of patients have been shown to have recurrence of nasal polyps within 5 years after surgery, with 47% requiring revision surgery in the same time period.

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.

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.

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.

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.

Urticarial vasculitis (also known as "chronic urticaria as a manifestation of venulitis", "hypocomplementemic urticarial vasculitis syndrome", "hypocomplementemic vasculitis" and "unusual lupus-like syndrome") is a skin condition characterized by fixed urticarial lesions that appear histologically as a vasculitis.

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.