Polymyositis (pol-e-my-o-SY-tis) is an uncommon inflammatory disease that causes muscle weakness affecting both sides of your body. Polymyositis can make it difficult to climb stairs, rise from a seated position, lift objects or reach overhead.

Polymyositis most commonly affects adults in their 30s, 40s or 50s. It's more common in blacks than in whites, and women are affected more often than men. Polymyositis signs and symptoms usually develop gradually, over weeks or months.

While there is no cure for polymyositis, treatment — ranging from medications to physical therapy — can improve your muscle strength and function.

Symptoms Causes Complications

The muscle weakness associated with polymyositis involves the muscles closest to the trunk, such as those in your hips, thighs, shoulders, upper arms and neck. The weakness affects both the left and right sides of your body, and tends to gradually worsen.

When to see a doctor

Seek medical attention if you develop unexplained muscle weakness.

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