In severe cases of PM and DM with systemic signs, an initial three to five days on intravenous corticosteroid (methylprednisolone) may be used; but normally treatment begins with a single daily (after breakfast) high dose of oral corticosteroid (prednisone). After a month or so the strength of every second day's dose is very gradually reduced over three to four months, to minimize the negative effects of the prednisone. When a high dose of prednisone cannot be reduced without losing muscle strength, or when prednisone is effective but it is producing significant complications, "steroid sparing" oral immunosuppressants such as azathioprine, mycophenolate mofetil, methotrexate and cyclosporine, may be used in combination with reduced prednisone. Some of these steroid sparing drugs can take several months to demonstrate an effect.

To minimize side effects, patients on corticosteroids should follow a strict high-protein, low-carbohydrate, low-salt diet; and with long-term corticosteroid use a daily calcium supplement and weekly vitamin D supplement (and a weekly dose of Fosamax for postmenopausal women) should be considered.

For patients not responding to this approach there is weak evidence supporting the use of intravenous immunoglobulin, ciclosporin, tacrolimus, mycophenolate mofetil and other agents; and trials of rituximab have indicated a potential therapeutic effect.

There have been few randomized treatment trials, due to the relative rarity of inflammatory myopathies. The goal of treatment is improvement in activities of daily living and muscle strength. Suppression of immune system activity (immunosuppression) is the treatment strategy. Patients with PM or DM almost always improve to some degree in response to treatment, at least initially, and many recover fully with maintenance therapy. (If there is no initial improvement from treatment of PM or DM, the diagnosis should be carefully re-examined.) There is no proven effective therapy for IBM, and most IBM patients will need assistive devices such as a cane, a walking frame or a wheelchair. The later in life IBM arises, the more aggressive it appears to be.

There is no standard course of treatment to slow or stop the progression of the disease. sIBM patients do not reliably respond to the anti-inflammatory, immunosuppressant, or immunomodulatory medications. Management is symptomatic. Prevention of falls is an important consideration. Specialized exercise therapy may supplement treatment to enhance quality of life. Physical therapy is recommended to teach the patient a home exercise program, to teach how to compensate during mobility-gait training with an assistive device, transfers and bed mobility.

Treatment for acquired noninflammatory myopathy is directed towards resolution of the underlying condition, pain management, and muscle rehabilitation.

Drug induced ANIMs can be reversed or improved by tapering off of the drugs and finding alternative care. Hyperthyroidism induced ANIM can be treated through anti-thyroid drugs, surgery and not eating foods high in Iodine such as kelp. Treatment of the hyperthyroidism results in complete recovery of the myopathy. ANIM caused by vitamin D deficiency can easily be resolved by taking vitamin supplements and increasing one's exposure to direct sunlight.

Pain can be managed through massaging affected areas and the use of nonsteroidal anti-inflammatory drugs (NSAIDs).

Exercise, physical therapy, and occupational therapy can be used to rehabilitate affected muscle areas and resist the atrophy process.

As with all myopathies, the use of walkers, canes, and braces can assist with the mobility of the afflicted individual.

Unfortunately, treatment for the anti-synthetase syndrome is limited, and usually involves immunosuppressive drugs such as glucocorticoids. For patients with pulmonary involvement, the most serious complication of this syndrome is pulmonary fibrosis and subsequent pulmonary hypertension.

Additional treatment with azathioprine and/or methotrexate may be required in advanced cases.

Prognosis is largely determined by the extent of pulmonary damage.

Treatment is palliative, not curative (as of 2009).

Treatment options for lower limb weakness such as foot drop can be through the use of Ankle Foot Orthoses (AFOs) which can be designed or selected by an Orthotist based upon clinical need of the individual. Sometimes tuning of rigid AFOs can enhance knee stability.

Canakinumab has been approved for treatment of HIDS and has shown to be effective. The immunosuppressant drugs etanercept and anakinra have also shown to be effective. Statin drugs might decrease the level of mevalonate and are presently being investigated. A recent single case report highlighted bisphosphonates as a potential therapeutic option.

There is currently no cure for the disease but treatments to help the symptoms are available.

Because different types of myopathies are caused by many different pathways, there is no single treatment for myopathy. Treatments range from treatment of the symptoms to very specific cause-targeting treatments. Drug therapy, physical therapy, bracing for support, surgery, and massage are all current treatments for a variety of myopathies.

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.

Because lack of sialic acid appears to be part of the pathology of IBM caused by GNE mutations, clinical trials with sialic acid supplements, and with a precursor of sialic acid, N-Acetylmannosamine, have been conducted, and as of 2016 further trials were planned.

The first line treatment for polymyositis is corticosteroids. Specialized exercise therapy may supplement treatment to enhance quality of life.

Currently there is no cure for myotubular or centronuclear myopathies. Treatment often focuses on trying to maximize functional abilities and minimize medical complications, and involvement by physicians specializing in Physical Medicine and Rehabilitation, and by physical therapists and occupational therapists.

Medical management generally involves efforts to prevent pulmonary complications, since lung infections can be fatal in patients lacking the muscle strength necessary to clear secretions via coughing. Medical devices to assist with coughing help patients maintain clear airways, avoiding mucous plugs and avoiding the need for tracheostomy tubes.

Monitoring for scoliosis is also important, since weakness of the trunk muscles can lead to deviations in spinal alignment, with resultant compromise of respiratory function. Many patients with congenital myopathies may eventually require surgical treatment of scoliosis.

There is no specific treatment but triggering anesthetics are avoided and relatives are screened for "RYR1" mutations as these may make them susceptible to MH.

The standard treatment is chenodeoxycholic acid (CDCA) replacement therapy. Serum cholesterol levels are also followed. If hypercholesterolemia is not controlled with CDCA, an HMG-CoA reductase inhibitor ("statins" such as simvastatin) can also be used.

There is no cure for dermatomyositis, but the symptoms can be treated. Options include medication, physical therapy, exercise, heat therapy (including microwave and ultrasound), orthotics and assistive devices, and rest. The standard treatment for dermatomyositis is a corticosteroid drug, given either in pill form or intravenously. Immunosuppressant drugs, such as azathioprine and methotrexate, may reduce inflammation in people who do not respond well to prednisone. Periodic treatment using intravenous immunoglobulin can also improve recovery. Other immunosuppressive agents used to treat the inflammation associated with dermatomyositis include cyclosporine A, cyclophosphamide, and tacrolimus. Physical therapy is usually recommended to prevent muscle atrophy and to regain muscle strength and range of motion. Many individuals with dermatomyositis may need a topical ointment, such as topical corticosteroids, for their skin disorder. They should wear a high-protection sunscreen and protective clothing. Surgery may be required to remove calcium deposits that cause nerve pain and recurrent infections.

Antimalarial medications, especially hydroxychloroquine and chloroquine, are used to treat the rashes, as they are in similar conditions.

Rituximab is used when people don't respond to other treatments.

As of 2016, treatments for amyopathic dermatomyositis in adults did not have a strong evidence base; published treatments included antimalarial medications, steroids, taken or orally or applied to the skin, calcineurin inhibitors applied to the skin, dapsone, Intravenous immunoglobulin (IVIG), methotrexate, azathioprine, and mycophenolate mofetil. None appear to be very effective but among them, IVIG has had the best outcomes.

Although there is no cure for NM, it is possible, and common for many people live healthy active lives even with moderate to severe cases. Research continues to seek ways to ameliorate debilitating symptoms and lengthen the life-span in quality ways for those affected. Some people have seen mild improvements in secretion handling, energy level, and physical functioning with supplemental L-tyrosine, an amino acid that is available through health centers. Some symptoms may worsen as the patient ages. Muscle loss increases with age naturally, but it is even more significant with nemaline myopathy.

Currently, there are no treatments for any of the congenital myopathies. Depending on the severity, there are different therapies available to help alleviate any pain and aid patients in performing varying activities. For example, many congenital myopathy patients are involved in physical or occupational therapy in an attempt to strengthen their skeletal muscles. Orthopedic surgery is usually necessary to correct skeletal deformities secondary to muscle weakness, such as scoliosis. Survival is typically determined by the level of respiratory muscle insufficiency.

At present, Nemaline myopathy does not have a cure. Nemaline myopathy is a very rare disease that only effects 1 out of 50,000 on average, although recent studies show that this number is even smaller. There are a number of treatments to minimize the symptoms of the disease. The treatments and procedures to help patients with nemaline myopathy vary depending on the severity of the disease. A possible accommodation could be the use of a stabilizer, such as a brace. Other means include moderate stretching and moderate exercise to help target muscles maintain maximum health.

As people with NM grow and develop throughout their lives, it is important for them to see a variety of health professionals regularly, including a neurologist, physical therapist, and others, such as speech therapists and psychologists, to help both the patient and family adjust to everyday life.

Camurati–Engelmann disease is somewhat treatable. Glucocorticosteroids, which are anti-inflammatory and immunosuppressive agents, are used in some cases. This form of medication helps in bone strength, however can have multiple side effects. In several reports, successful treatment with glucocoricosteroids was described, as certain side effects can benefit a person with CED. This drug helps with pain and fatigue as well as some correction of radiographic abnormalities.

Alternative treatments such as massage, relaxation techniques (meditation, essential oils, spa baths, music therapy, etc.), gentle stretching, and especially heat therapy have been successfully used to an extent in conjunction with pain medications. A majority of CED patients require some form of analgesics, muscle relaxant, and/or sleep inducing medication to manage the pain, specifically if experiencing frequent or severe 'flare-ups' (e.g. during winter).

Treatment for TM is typically done with the collaboration of many medical specialists. Usually a neuromuscular specialist, an endocrinologist, a surgeon, and an ophthalmologist will combine their efforts to successfully treat patients with TM. If a patient develops significant to severe muscle degradation as a result of TM, a physical therapist may be consulted for rehabilitation.

Since excess thyroxine leads to onset of TM, the overall goal of treatment is to reduce to overproduction of thyroxine from the thyroid gland and restore normal thyroid homeostasis. This can be accomplished three ways including using medication, radiation, and surgery.

The first choice involves using medications to alleviate the symptoms and reverse the damage by blocking the production of thyroxine from the thyroid gland. Beta-blockers are used to alleviate the symptoms associated with TM. But beta-blockers do not reduce the damage done by excess thyroxine. Medications such as propylthiouracil and methimazole are administered to block the release of thyroxine from the thyroid and to block the damage thyroxine inflicts on muscle fiber tissue.

One treatment option is the use of radioactive iodine which directly destroys the overactive thyroid gland. The thyroid gland naturally uses iodine to produce thyroxine and other hormones. It cannot distinguish between normal iodine and the radioactive version. Administering the radioactive isotope causes the thyroid to take in the lethal iodine and quickly radiation destroys it. Typically overproduction of thyroxine using radio-iodine is blocked with one dose. The drawback to this treatment is the thyroid gland is completely destroyed and patients often develop hypothyroidism. Some do so only a few months after treatment while others may not be affected for 20–30 years. Hypothyroidism patients must begin a lifelong regimen of thyroid replacement hormones. While the onset of hypothyroidism is most common with radio-iodine treatment, the condition has been observed in patients treated with medication series and surgery.

The last option for TM treatment includes surgical removal of portions of the thyroid which can also be performed to restore thyroid homeostasis. This treatment option usually is done when overproduction of TM is caused by multinodular goiters. Since these goiters enlarge the thyroid and can cause the patient to become physically disfigured surgical treatment can alleviate both the aesthetic and physiological effects simultaneously.

Topical treatment for the skin changes of scleroderma do not alter the disease course, but may improve pain and ulceration. A range of NSAIDs (nonsteroidal anti-inflammatory drugs) can be used to ease painful symptoms, such as naproxen. There is limited benefit from steroids such as prednisone. Episodes of Raynaud's phenomenon sometimes respond to nifedipine or other calcium channel blockers; severe digital ulceration may respond to prostacyclin analogue iloprost, and the dual endothelin-receptor antagonist bosentan may be beneficial for Raynaud's phenomenon. The skin tightness may be treated systemically with methotrexate and ciclosporin. and the skin thickness treated with penicillamine.

Scleroderma renal crisis, the occurrence of acute renal failure and malignant hypertension (very high blood pressure with evidence of organ damage) in people with scleroderma, is effectively treated with drugs from the class of the ACE inhibitors. The benefit of ACE inhibitors extends even to those who have to commence dialysis to treat their kidney disease, and may give sufficient benefit to allow the discontinuation of renal replacement therapy.

Before the advent of modern treatments such as prednisone, intravenous immunoglobulin, plasmapheresis, chemotherapies, and other drugs, the prognosis was poor.

The cutaneous manifestations of dermatomyositis may or may not improve with therapy in parallel with the improvement of the myositis. In some people, the weakness and rash resolve together. In others, the two are not linked, with one or the other being more challenging to control. Often, cutaneous disease persists after adequate control of the muscle disease.

The risk of death from the condition is much higher if the heart or lungs are affected.

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.