Frequently Asked Questions

Dermatomyositis is a rare autoimmune disease that is usually characterized by skin rashes and muscle weakness. It occurs when the body’s immune system mistakenly attacks healthy tissue, leading to inflammation and damage.

If you’re navigating a new diagnosis, visit our Patient & Care Partners page to explore video stories from individuals and care partners living with dermatomyositis. You can also visit our Medical Experts page to watch leading dermatomyositis experts share their insights and answer key questions about the disease.

Doctors don’t know the exact cause of dermatomyositis, but it’s an autoimmune condition—where the immune system mistakenly attacks healthy tissue. This may be triggered by a mix of genetic factors, infections, medications, or environmental exposures. Check out this section What causes dermatomyositis? on our medical experts’ page where doctors provide further details on the current understanding of the causes.

Dermatomyositis is different from many other immune‑related conditions because it has a recognizable combination of skin changes and muscle involvement. People with dermatomyositis often develop distinctive rashes, such as a violet or purplish discoloration around the eyes (heliotrope rash) or raised, reddish‑purple areas on the knuckles (Gottron’s papules). It may also cause muscle weakness frequently affecting the hips, thighs, and shoulders, although some individuals experience skin symptoms without muscle weakness (which may be called “amyopathic” dermatomyositis). Other features such as lung disease or difficulty swallowing may be present. These characteristic features help differentiate dermatomyositis from other conditions that affect different organs or present with different patterns.

Hear from patients living with dermatomyositis and more detailed explanations by medical experts on how dermatomyositis differs from other autoimmune diseases.

Skin involvement is often the first indicator of dermatomyositis. As previously mentioned, these signs are often highly specific to this condition and include the following:

• Heliotrope Rash: A reddish-purple discoloration of the upper eyelids, often accompanied by swelling.
• Gottron’s Papules: Raised, violet-colored bumps or scales on the knuckles, elbows, or knees.
• V-Sign and Shawl Sign: A flat, red rash that appears on the chest (V-sign) or across the back and shoulders (Shawl sign).
• Holster Sign: Purple or red rash over the lateral hips and upper thighs.
• Photosensitivity: Increasing redness, swelling, or itch in response to sun exposure.
• Pruritus: Intense itching can be a prominent feature.

To learn about the typical diagnosis journey and the symptoms of dermatomyositis from a patient’s point of view, explore our Diagnosis & Discovery and How Dermatomyositis Affects the Body video sections.

Dermatomyositis primarily causes proximal muscle weakness, affecting the muscles closest to the trunk of the body, such as the hips, thighs, shoulders, and neck. This weakness is usually symmetrical, meaning it affects both sides of the body equally. Patients may find it difficult to rise from a chair, climb stairs, or lift objects above their head. For more information on the muscle weakness and its effects on daily life, check out the How Dermatomyositis Affects the Body for a patient perspective and How does dermatomyositis affect daily life? for a medical expert perspective.