- Polymyositis
- Dermatomyositis
- Systemic lupus erythematosus (SLE)
- Scleroderma
- Sjögren's syndrome
- Inclusion body myositis
- Trichinosis (Trichinella infection)
- Sarcocystosis
Other causes of proximal muscle weakness
- Polymyalgia rheumatica
- Endocrine: hypothyroidism, hyperthyroidism, Cushing's syndrome
- Alcoholism
- Drugs: corticosteroids, statins, clofibrate, colchicine, chloroquine, emetine, aminocaproic acid, bretylium, penicillamine, drugs causing hypokalemia
- HIV myopathy
- Hyperparathyroidism
- Spinal stenosis
- Osteomalacia
- Mitochondrial myopathy
- Diabetic lumbosacral plexopathy