What causes shoulder pain?

Shoulder pain has a way of arriving without a clear explanation. You reach for something overhead, sleep awkwardly, throw a ball, or wake up one morning and simply cannot move your arm the way you could the day before. What's actually wrong is rarely obvious. You may have heard terms like rotator cuff tear, frozen shoulder, or impingement and wondered which one applies to you — or whether any of them do.

The difficulty is that many shoulder conditions look alike on the surface. Pain when lifting your arm, stiffness, weakness, aching at night — these symptoms appear across several different diagnoses, which makes self-identification genuinely hard. This article, written by a team of physiotherapists, walks through the five most common causes of shoulder pain, what distinguishes each one, and what getting better actually looks like.

The most common causes of shoulder pain

These conditions account for the large majority of shoulder pain. They are not mutually exclusive — some people have more than one — but understanding each one separately is the clearest starting point.

Cervical radiculopathy (pinched nerve in the neck)

This one starts in the neck, not the shoulder. Cervical radiculopathy is a pinched nerve in the cervical spine — the section of the spine that runs through your neck — which sends pain, tingling, or numbness radiating outward along the path of the nerve. The shoulder is one of the most common places that pain lands. ^1,2

You may have cervical radiculopathy if:

• You have sharp, burning, or radiating pain — typically only on one side — running through the neck, shoulder, arm, or hand¹
• You experience tingling or numbness in the arm or hand, or the feeling that part of your arm has fallen asleep
• Moving your neck — tilting or rotating it — changes or worsens the pain ³

Rotator cuff tear

The rotator cuff is a group of four muscles and tendons that hold the shoulder joint in place and allow your arm to rotate and lift freely. When one or more of those tendons tears — through a sudden injury, repetitive overhead movement, or simply the gradual wear of ageing — the result can range from a dull ache to significant pain and weakness. ⁴

Rotator cuff tears are more common than most people realise. Research suggests that about one in five people over 50 has a tear — many without knowing it. ⁵ When tears do cause symptoms, the pattern tends to be recognisable.

You may have a rotator cuff tear if:

• You have pain in the shoulder when reaching overhead or to the side
• You notice weakness in the arm — difficulty lifting objects or finding it hard to hold things
• You experience pain at night, especially when lying on the affected shoulder ⁴

Shoulder impingement

Also known as swimmer's shoulder, impingement occurs when the space between the rotator cuff tendons and the bone on top of the shoulder (the acromion) becomes too narrow. The tendons get compressed and irritated — particularly during overhead movement — leading to pain and inflammation that can worsen over time if left untreated. ⁶

You may have shoulder impingement if:

• You have pain when lifting your arm to the side or overhead, often between 60 and 120 degrees of elevation
• You feel pain at the front or side of the shoulder that worsens with reaching or carrying
• Weakness or stiffness makes overhead activity difficult, and symptoms ease when your arm is at rest ⁶

Labrum tear

The labrum is a ring of cartilage that lines the shoulder socket, helping keep the joint stable. A tear in this cartilage can happen from a sudden force — a fall, a dislocation, or a forceful overhead movement — or through repetitive strain over time. There are two main types, and they tend to affect different groups of people.

SLAP tear. A SLAP tear occurs at the top of the labrum where the biceps tendon attaches. It is most common in people who throw, swing, or perform repetitive overhead motions. ⁷

You may have a SLAP tear if:

• You feel pain at the front of the shoulder near the biceps tendon
• You notice a clicking, popping, or grinding sensation in the shoulder ⁷
• You feel reduced strength or range on overhead movements

Bankart tear. A Bankart tear occurs at the lower rim of the labrum and is typically caused by a shoulder dislocation. ⁸

You may have a Bankart tear if:

• You feel as if your shoulder is loose, slipping, or likely to dislocate
• Your shoulder has dislocated, and dislocations are becoming more frequent or easier to trigger ⁸
• You feel a dull ache in the shoulder and upper arm, or a catching sensation in the joint

Frozen shoulder

Frozen shoulder — also known as adhesive capsulitis — develops when the tissue surrounding the shoulder joint becomes inflamed and progressively scarred, tightening around the joint until movement is severely restricted. ⁹ It is one of the more disruptive shoulder conditions because it tends to worsen before it gets better, and can take months to resolve even with good treatment.

The condition progresses through stages.¹⁰ In the early freezing stage, which can last up to nine months, pain builds gradually and movement begins to restrict. This is often the most painful phase. In the frozen stage, which can last four months to a year, pain may plateau or ease slightly — but stiffness takes over, and using the shoulder at all becomes very difficult. A third stage, the thawing stage, sees gradual recovery of movement.

You may have frozen shoulder if:

• Movement is progressively restricted in all directions — not just overhead ⁹
• You have a gradual, aching pain that tends to be worse at night
• The shoulder was recently immobilised — for example, after an injury, surgery, or a period of forced rest ⁹

Early physiotherapy matters here more than for most other conditions. Starting treatment sooner shortens the freezing phase and can meaningfully reduce the overall time to recovery. ¹¹

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What to do about it

Many of these conditions share surface-level symptoms, which is why a professional assessment matters. Some require imaging — an MRI, ultrasound, or CT scan — to confirm what's happening. If your pain is severe, worsening, or accompanied by numbness or tingling, contact a healthcare provider rather than waiting.

The good news holds across all five conditions: surgery is rarely necessary. Shoulder pain responds well to conservative treatment. Guided exercise, strengthening, range of motion work, and manual therapy consistently produce results that equal or exceed surgical outcomes for most people — without an operation, a recovery ward, or months of post-surgical rehabilitation. ^6,12

Shoulder pain that goes unaddressed tends to compound. Muscles compensate, movement patterns shift, and conditions that are straightforward to treat early become harder to resolve later. In Portugal, getting an in-person physiotherapy appointment through the SNS can mean a wait of weeks or months. At-home physiotherapy through Sword starts sooner.

The bottom line

Shoulder pain is rarely a mystery that has to stay unsolved. The five conditions in this article account for most of what people experience, and each one has a recognisable pattern — if you know what to look for.

What they share is more important than what separates them: all five respond to physiotherapy, none require surgery as a first step, and all of them get harder to treat the longer they go unaddressed. The conditions that feel permanent rarely are — but they need the right care to resolve.

If your shoulder has been bothering you, getting an accurate picture of what's happening is the first step. From there, recovery is more achievable than most people expect.