Medicines for Polymyositis

What it is

Polymyositis is a rare autoimmune condition (one of a group called inflammatory myopathies) in which the immune system attacks the muscles, causing inflammation and progressive muscle weakness. The weakness typically affects the muscles closest to the trunk — around the shoulders, upper arms, hips and thighs — and usually develops gradually over weeks to months, and on both sides of the body. This causes difficulty with activities that use these muscles, such as climbing stairs, getting up from a chair or the floor, lifting the arms (for example to brush hair or reach overhead), and, in some cases, difficulty swallowing if the muscles involved in swallowing are affected. There may also be muscle aching, tiredness, and general symptoms. Polymyositis is related to dermatomyositis (which additionally causes a characteristic skin rash), but in polymyositis there is no rash. Because it affects the muscles and can sometimes involve other organs, and is occasionally associated with other conditions, it is assessed and managed by specialists. Although it is a serious condition, treatment can control the inflammation and improve muscle strength in many people.

How it is treated

Polymyositis is diagnosed and managed by specialists (such as rheumatologists or neurologists), usually with a combination of tests — blood tests (including muscle enzymes that are raised when muscle is inflamed), tests of muscle and nerve function, scans, and often a muscle biopsy (a small sample of muscle) to confirm the diagnosis. Treatment aims to reduce the immune-driven inflammation, restore and preserve muscle strength, and manage any other affected organs. The mainstay is medicines that calm the overactive immune system — typically steroids initially (often at higher doses to bring the inflammation under control, then reduced), usually alongside other immune-suppressing (or immune-modulating) medicines that allow the steroid dose to be lowered over time and help control the disease longer-term. Physiotherapy is important to maintain and rebuild muscle strength and function as the inflammation is controlled, and support for daily activities helps. Because it can occasionally affect other organs (such as the lungs) or be associated with other conditions, monitoring and appropriate screening are part of care. Treatment is tailored and monitored over time. The reassuring message is that polymyositis is a treatable condition — medicines that calm the immune system, together with physiotherapy, can control the inflammation and improve muscle strength for many people, and specialist care guides long-term management.