A sac the thickness of paper, causing pain everyone blames on the neck.

SUBACROMIAL BURSA

The subacromial bursa, a fluid sac as thin as paper, sits between your rotator cuff and the bone above it. When it is the problem, the pain is felt in the upper arm and blamed on the neck.

Where does it hurt if you have bursitis in your shoulder?

Subacromial pain is felt over the outer shoulder and the upper third of the arm. It often stops around the deltoid insertion (where the shoulder muscle attaches to the arm). It rarely goes past the elbow and almost never reaches the hand. That pattern is the first thing that separates it from a C5 or C6 root problem, which travels the whole way down.

The second thing is what brings it on. Reaching overhead, reaching behind the back, and lying on that side at night are the subacromial trio. Turning the head is not.

The painful arc, and what it means

Pain through roughly the middle of the elevation range (lifting the arm) that eases at the top is the classic sign. It happens because the cuff and bursa are squeezed under the acromion (the bony roof of the shoulder) in that arc. It is one of the more useful physical findings in shoulder medicine. Still, like every single test, it is more convincing as part of a cluster than on its own.

Weakness on resisted abduction (lifting the arm out to the side against resistance) that is limited by pain, not by loss of power, is bursa or tendon. Weakness that is present without pain is a different question. It raises a cuff tear or a nerve problem.

Why this page exists on a neck website

Because the overlap runs both ways, and it is well documented. A systematic review of overlapping, masquerading and causative cervical spine and shoulder pathology exists precisely because clinicians keep treating one when the driver is the other. A person can have a degenerate neck on imaging. They can also have a subacromial problem generating every symptom they actually feel — and then have their neck treated for a year.

Our position: the shoulder gets examined at the neck appointment, every time. It takes two minutes. And it changes the plan often enough to justify itself many times over.

How do you fix subacromial bursitis?

Loaded rotator cuff rehab is the backbone, and it has a substantial evidence base. It is not gentle stretching — it is progressive strengthening. The people who do it properly get the lasting results.

A subacromial corticosteroid injection has a role. It helps confirm the source. It also opens a window in which rehab becomes possible. It is not a treatment in its own right. Repeated shots into a tendon area are not a plan. Say a bursa is truly inflamed, and a person cannot begin rehab because of it. Then one well-placed injection is a reasonable, evidence-supported step.

Is it a rotator cuff tear or bursitis?

• Night pain with true weakness and a positive lag sign (the arm cannot hold a position) — think cuff tear. Imaging is warranted.
• Pain past the elbow, or into the hand — think neck.
• A stiff shoulder with limited passive external rotation (turning the arm outward when someone else moves it) — that is adhesive capsulitis (frozen shoulder), not impingement. It is treated differently.
• Pain localized to the top of the shoulder at the joint line — that is the AC joint.

Why does shoulder bursitis hurt more at night?

Lying on the affected side compresses the bursa directly. Lying on the other side lets the arm fall forward into the same position. Both hurt. That is why shoulder pain wrecks sleep more reliably than neck pain does.

Lie on the good side with a pillow under the affected arm, and put a pillow behind the back to stop rolling onto the bad one. This does more than most people expect. It is not a treatment for the underlying problem. But sleep affects pain enough to be worth arranging on purpose.

What the terminology confusion costs

Impingement, subacromial pain syndrome, bursitis and rotator cuff tendinopathy overlap heavily. Different clinicians use the terms interchangeably. Guidelines have moved toward the broader descriptive term. That is because the older mechanical model did not survive close study.

The practical result is that two people can be told two different diagnoses for the same shoulder. What matters more than the label is whether the treatment is progressive loading. That is because it is what the evidence supports, whichever name is used.

Does a cortisone shot help subacromial bursitis?

Guidelines from multidisciplinary groups (teams from several fields) have been fairly consistent. A corticosteroid shot gives short-term relief. Exercise gives lasting relief. And the two together beat either one used in place of the other. Trials exist that compare corticosteroid injection, physical therapy and combined treatment in chronic (long-lasting) shoulder pain. They support that reading.

Our practical rule is that an injection needs a job. If the job is to let somebody sleep and start loading, that is a good job. If the job is to be the treatment, it is the wrong tool. Repeating it will make that clear over about a year.

What the shoulder examination adds to a neck appointment

Passive versus active range, which separates a stiff joint from a painful one. Resisted testing in the specific planes, which pins the problem to the cuff. The painful arc. Palpation (pressing) of the AC joint. And the cervical provocation tests done right alongside. That way the two are compared in the same few minutes, not in appointments six weeks apart.

Doing them together is the whole point. A person who has seen a shoulder service and a neck service separately has had both examinations. Still, nobody has compared them.

Orthobiologic treatment options

Most pain here is rotator cuff tendon wear, with the bursa irritated on top. When exercise has stalled and each steroid shot helps for less time, PRP placed into the worn tendon under ultrasound treats the tissue that is actually failing. In 2026 an international expert panel reached consensus on PRP for rotator cuff tendinitis. We pair it with cuff and shoulder blade loading, because the tendon only gets stronger under load.

You stay awake with local numbing, and most people drive home. It is done at our regenerative clinic, 4477 Woodson Rd in St. Louis. If the pain sits in the groove at the front, read biceps tendonitis. If the whole joint is stiff, read shoulder arthritis.

For PRP, bone marrow and fat side by side, read our orthobiologics overview for the neck and shoulder.

What people ask about shoulder-versus-neck pain

My MRI showed bursitis. Is that my answer?

Not necessarily. Bursal signal change is common on imaging. It needs to match your examination and your pain pattern before it earns the diagnosis. AC joint pain.

Can my neck cause shoulder pain?

Yes, and this is exactly the confusion. C5 refers pain to the outer shoulder convincingly. The pattern of what brings it on, and how far the pain travels, are what separate them. Neck or shoulder? C5 refers to the outer shoulder and stops at the elbow, which is the tell.

Is an injection going to weaken my tendon?

Repeated injections into a tendon area are a genuine concern. That is why we use them to open a rehab window rather than as an ongoing treatment. Rotator cuff, or the neck?

How long does rehabilitation take?

Three months of consistent loaded work before judging it. Most people who report failure stopped at four weeks. How long neck pain should take to settle.

What makes subacromial bursitis flare up?

Three movements bring it on: reaching overhead, reaching behind your back, and lying on the affected side at night. Partway through lifting the arm, the rotator cuff and bursa are squeezed under the bone above them. That is why pain peaks in the middle of the movement and eases at the top. Turning your head does not bring it on, and that points away from the neck.

Is shoulder impingement the same as bursitis?

Nearly. Impingement, subacromial pain syndrome, bursitis and rotator cuff tendinopathy overlap heavily. Different clinicians use them for the same shoulder. Guidelines have moved toward a broader term because the older pinching model did not hold up. The label matters less than the treatment. Progressive loading of the rotator cuff is what the evidence supports, under any of those names.

How can I sleep with shoulder bursitis?

Lie on the good side with a pillow under the affected arm, so the arm does not fall forward into the painful position. Put a pillow behind your back so you do not roll onto the sore shoulder. It does not treat the underlying problem. But sleep affects pain enough that it is worth arranging on purpose while the rehabilitation does its work.

Related reading

• Rotator cuff, or the neck?
• AC joint pain
• Cervical radiculopathy
• Shoulder pain that starts in the neck
• Thoracic outlet syndrome
• Why your MRI does not explain it