Adhesive capsulitis, also known as frozen shoulder, is a condition associated with shoulder pain and stiffness. It is a common shoulder ailment that is marked by pain and a loss of range of motion, particularly in external rotation. There is a loss of the ability to move the shoulder, both voluntarily and by others, in multiple directions. The shoulder itself, however, does not generally hurt significantly when touched. Muscle loss around the shoulder may also occur. Onset is gradual over weeks to months. Complications can include fracture of the humerus or biceps tendon rupture.

The cause in most cases is unknown. The condition can also occur after injury or surgery to the shoulder. Risk factors include diabetes and thyroid disease. The underlying mechanism involves inflammation and scarring. The diagnosis is generally based on a person's symptoms and a physical exam. The diagnosis may be supported by an MRI. Adhesive capsulitis has been linked to diabetes and hypothyroidism, according to research. Adhesive capsulitis was five times more common in diabetic patients than in the control group, according to a meta-analysis published in 2016.

The condition often resolves itself over time without intervention but this may take several years. While a number of treatments, such as NSAIDs, physical therapy, steroids, and injecting the shoulder at high pressure, may be tried, it is unclear what is best. Surgery may be suggested for those who do not get better after a few months. About 4% of people are affected. It is more common in people 40–60 years of age and in women.