What Causes Shoulder Pain? Left, Right, and What the Side Actually Tells You

AI Overview

• Most shoulder pain comes from the tendons and muscles around the joint, the joint itself, postural strain, or pain referred from the neck.
• The side that hurts usually reflects which arm you use or sleep on, not something sinister. The main exception is left shoulder pain with chest pain, breathlessness, nausea or jaw pain, which can signal a heart attack and needs emergency care.
• Shoulder blade pain is often not a shoulder problem at all. It usually comes from the upper back or neck.
• Neck-referred pain is one of the most commonly missed causes. It follows a nerve path down the arm and does not change much when you move the shoulder.
• An ICD-10 code describes where the pain is, not what causes it. It is an administrative label, not a diagnosis.

A list of possible causes is easy to find. What is harder, and what actually matters, is working out which one is yours. This guide walks through each cause, what it typically feels like, and what the side that hurts does and does not tell you.

Why the shoulder goes wrong so often

The shoulder trades stability for movement. Unlike the hip, which sits deep in a bony socket, the shoulder is held together largely by muscle and tendon. That is what lets you throw a ball, reach behind your back and lift something over your head. It is also what makes it easy to injure.

Because so many structures are involved, shoulder pain reasons vary widely. The pain can come from a tendon, from the joint, from the muscles around the shoulder blade, or from somewhere else entirely.

The short answer: what causes shoulder pain?

The most common shoulder pain causes are tendon problems in the muscles that stabilise the joint, irritation or inflammation in the joint itself, frozen shoulder, postural strain around the shoulder blade, and pain referred from the neck. Overuse and sudden injury account for most of the rest.

Serious causes are uncommon, but they exist, and they are covered further down. They are worth knowing about.

Left shoulder pain: what it usually means, and when to worry

For most people, left shoulder pain has a straightforward mechanical explanation. It reflects which arm you use, which side you sleep on, or which shoulder you injured. Left-handed people get left shoulder pain. People who sleep on their left side get left shoulder pain. There is usually nothing sinister about the side itself.

That said, there is one important exception, and it is worth being completely clear about it.

When left shoulder pain is an emergency

Left shoulder or left arm pain can be a sign of a heart attack, particularly when it comes together with any of the following:

• Chest pain, pressure or tightness
• Shortness of breath
• Nausea, sweating or light-headedness
• Pain spreading to the jaw or neck

If you have that combination, call emergency services immediately. Do not book a chiropractor. Do not wait to see whether it passes.

This is uncommon. The overwhelming majority of left shoulder pain is musculoskeletal and entirely benign. But it costs nothing to know the difference, and a clinic that does not tell you this is not doing its job.

One useful distinction: pain that builds gradually and changes when you move the arm is usually mechanical. Pain that arrives suddenly at rest, with the symptoms above, needs urgent medical attention.

Right shoulder pain

The mechanical causes of right shoulder pain are identical to the left. A tendon problem feels the same on either side, and frozen shoulder does not care which shoulder it affects. If you are right-handed, or you sleep on your right side, that alone explains most right-sided pain.

Occasionally, right shoulder pain can be referred from the gallbladder or the liver. This is uncommon and it rarely appears on its own. It usually comes with abdominal pain, nausea, or a feeling of fullness after eating. If that describes you, see a doctor rather than a chiropractor.

Pain in the shoulder blade

Shoulder blade pain is very common, and here is the thing most articles miss: it often is not a shoulder problem at all. The ache you feel between or underneath the shoulder blade usually comes from the upper back or the neck, not from the shoulder joint.

The usual causes are postural strain from long hours at a desk, irritation of the small joints where the ribs meet the spine, and muscle tension across the upper back. If the pain is worse at the end of a working day and eases at the weekend, posture is almost certainly involved. This kind of upper-back muscle tension often responds to soft tissue and myofascial work alongside postural correction.

Pain in this area can also be referred from the neck, which is why it is worth having the neck examined even when the shoulder blade is where it hurts.

When shoulder pain is actually coming from your neck

An irritated nerve in the neck frequently presents as shoulder pain, and this is one of the most commonly missed causes. The pain is felt in the shoulder, so the shoulder gets treated, and it does not get better, because the shoulder was never the problem.

The tell is that the pain follows a nerve path rather than the joint. It often travels down the arm, and it may come with tingling, numbness or a feeling of weakness in the hand. It also tends not to change much when you move the shoulder itself, which is a useful clue. If this sounds like your pain, it is worth reading about neck pain as the likely source.

This is why neck and shoulder pain are so often assessed together. A practitioner who only examines the shoulder can treat it for months while the actual cause sits higher up.

What the ICD-10 code for shoulder pain means

An ICD-10 code is a standard international code used on medical records and insurance claims. If you have seen one on a report or a claim form, that is entirely routine and it is not a cause for concern.

The important thing to understand is what the code does and does not tell you. It describes where the pain is, not what is causing it. It is a label for administrative purposes, not a diagnosis. A code confirming pain in the left shoulder tells your insurer where the problem is; it says nothing about whether that pain is a tendon, a joint, or referred from your neck.

Codes differ depending on whether the pain is in the left shoulder, the right shoulder, or unspecified. If you want to know the exact code on your paperwork, ask the clinician who issued it. They will be able to tell you what it means in your case.

How to tell what is causing your shoulder pain

The pattern of the pain is often the most useful clue you have.

Overuse and sudden injury are worth mentioning separately. A soft tissue strain from lifting something awkwardly tends to announce itself immediately. Sports injuries involving the shoulder are common in swimming, racquet sports and overhead lifting, and they often build gradually rather than arriving all at once.

When to get shoulder pain checked

Most shoulder pain is not dangerous. The following are uncommon, but they need a doctor rather than a chiropractor, and some need emergency care.

Seek emergency care immediately if you have:

• Left shoulder or arm pain with chest pain, breathlessness, nausea, sweating or jaw pain. This can indicate a heart attack. Call emergency services.
• Sudden pain at the tip of the shoulder in a woman who could be pregnant, particularly alongside abdominal pain, dizziness or faintness. This can be a sign of a ruptured ectopic pregnancy, which is a medical emergency. Go to A and E.

See a doctor promptly if you have:

• Shoulder pain after a fall or impact, with visible deformity or an inability to move the arm
• Sudden loss of strength, or being unable to lift the arm at all
• Fever together with a hot, swollen shoulder joint
• Numbness or weakness travelling into the hand

A responsible clinic screens for all of this before treating you, and will send you to a doctor if it finds any of it. If a practitioner does not ask, that tells you something.

A list of causes is not a diagnosis

Shoulder pain is the complaint where getting the diagnosis wrong is most common, and it is easy to see why. A tendon problem, a joint problem, frozen shoulder and neck-referred pain can all feel broadly similar to the person experiencing them. They need completely different treatment. Neck-referred pain treated as a shoulder problem does not improve, because nobody is treating the neck.

A first appointment at Franklin is an assessment, not a treatment conveyor belt. We take a history, watch how the shoulder and the neck actually move, test the structures individually, and only then say what we think is going on. Chiropractors and physiotherapists work under one roof here, all DHA-licensed practitioners, which matters more for shoulders than for almost any other complaint, because the real question is so often whether this is the shoulder or the neck.

If your symptoms need a doctor rather than us, we will say so. If you have had shoulder pain for more than a couple of weeks, or it is not responding to what you have tried, working out what is actually wrong is the place to start, and that begins with a proper chiropractic and physiotherapy assessment. You can also see the full range of conditions we treat for related problems.

Frequently Asked Questions