Understanding shoulder pain: the rotator cuff and frozen shoulder

A plain-language guide to the most common causes of shoulder pain in adults: rotator cuff related shoulder pain and frozen shoulder. What they are, how they feel, and why most people get better.

6 min read · last reviewed October 1, 2026

Your shoulder is the most mobile joint in your body. It lets you reach up to a high shelf, behind your back to tuck in a shirt, and out to the side to hug someone. All that movement comes at a price: the shoulder relies on muscles and tendons to keep it steady, and those tissues can get sore.

This guide explains the two most common causes of shoulder pain in adults: rotator cuff related shoulder pain and frozen shoulder. The encouraging news is that most people with either one get better.

How your shoulder works

Your shoulder is a ball-and-socket joint. The ball at the top of your upper arm bone sits in a shallow socket on your shoulder blade, a bit like a golf ball on a tee. Because the socket is so shallow, the shoulder needs help to stay steady.

That help comes from the rotator cuff: four muscles that start on your shoulder blade and wrap around the ball with their tendons. They keep the ball centred in the socket and help you lift and turn your arm. A small fluid-filled sac called a bursa sits on top of the rotator cuff and helps it glide.

Rotator cuff related shoulder pain

This is the most common cause of shoulder pain in adults, especially after age 40. You may have heard it called:

• Shoulder impingement or subacromial pain
• Rotator cuff tendinopathy or tendinitis
• Subacromial bursitis
• A partial rotator cuff tear

These names describe slightly different things, but they often overlap and are treated in much the same way. Many experts now use the umbrella term "rotator cuff related shoulder pain."

How does it feel?

• Pain on the outside of the upper arm, sometimes spreading toward the elbow
• Pain when lifting your arm out to the side or overhead, especially between shoulder and head height
• Pain reaching behind your back
• Pain lying on that side at night
• The arm may feel weak, partly because of pain

Why does it happen? Often the tendons have been asked to do more than they were ready for, such as a weekend of painting a ceiling, a new gym routine or a busy season at work. Age-related changes in the tendons also play a part. Sometimes there is no clear trigger at all.

About rotator cuff tears. Rotator cuff tendons naturally change with age, and tears become common. Studies that scanned people's shoulders found that many people over 60 have a rotator cuff tear with no pain at all. This means a tear on a scan isn't always the cause of your pain, and many people with tears do well with exercise.

There is one important exception. If you suddenly can't lift your arm after a fall, a jolt or lifting something heavy, you may have a new tear. Get it checked within a week or two, because some of these do better with early repair.

Something you can do today: Keep your shoulder moving gently within a comfortable range. Avoid keeping it completely still.

Frozen shoulder

Frozen shoulder (also called adhesive capsulitis) happens when the lining around the shoulder joint, called the capsule, becomes inflamed. Over time it gets thick and tight, so the shoulder can't move freely.

Who gets it? It is most common between ages 40 and 60, and a little more common in women. People with diabetes or thyroid problems are more likely to get it. It can also follow an injury or surgery that kept the arm still.

How does it feel? Frozen shoulder often goes through stages:

1. Freezing: the shoulder becomes painful, often worse at night, and starts to stiffen.
2. Frozen: the pain may ease, but the shoulder is very stiff. Turning the arm outward, and reaching up or behind the back, is hard.
3. Thawing: movement slowly comes back.

The whole process can take from several months to a couple of years. That can feel like a long time, but nearly everyone gets better, and treatment can ease the pain and help you move along.

Other causes of shoulder pain

Shoulder pain can also come from arthritis of the shoulder joint, a dislocation or fracture, problems in the neck that cause pain felt in the shoulder, or, rarely, from the heart, lungs or other organs. Your doctor will check for these.

Shoulder or arm pain with chest discomfort, shortness of breath or sweating can be a heart attack. Call 9-1-1.

Do I need a scan?

Not usually at the start. Your doctor or physiotherapist can usually work out what is going on by asking about your symptoms and checking how your shoulder moves. A scan may be helpful if you've had an injury and can't lift your arm, if things aren't improving after a few months, or if surgery is being considered.

A hopeful outlook

Shoulders can be slow to settle, and patience is part of the treatment. But with time, gentle movement and the right exercises, most people get back to the things they love. Our guide Shoulder pain: your treatment options explains what helps.

Something you can do this week: Notice which movements bother your shoulder, and find another way to do those tasks for now.

Questions to ask your care team

• What do you think is causing my shoulder pain?
• Is it coming from my shoulder, or could it be my neck or something else?
• Do I need a scan? Why or why not?
• What movements should I avoid for now, and which should I keep doing?
• How long do you expect it to take to improve?
• If I have diabetes, does that change anything?

This article is general information, not medical advice. Talk with your health care team about your own situation. In an emergency, call 9-1-1 or your local emergency number.

In an emergency, call 9-1-1 or your local emergency number.

General information, not medical advice. It does not replace your own care team. If you think you or someone else is having a medical emergency, call 9-1-1 or your local emergency number. If you are in crisis or thinking about suicide, call or text 9-8-8 (Canada and the US).

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