Written by Zita Sham, Fairuuz Saleh and Shiv Mohan Banka, Principal Physiotherapists at Phoenix Rehab.Clinically reviewed by Louise Yow, Principal Physiotherapist & Director, AHPC A1300363H.Last reviewed 2 November 2026.
It hurts halfway down the arm, on the outside, where a sleeve seam would sit. Reaching back for the seat belt sets it off. So does the bra clasp, the top cupboard, and lying on that side at 2am. You have pressed the sore spot and it is not sore. The shoulder itself feels fine, which is why you keep typing “upper arm” into the search bar and not “shoulder”.
Most upper arm pain is a shoulder problem that hurts somewhere else. This page covers why the pain lands halfway down the arm, the signs that mean a doctor or 995 first, how to tell the rotator cuff from the biceps from the neck from a bone, right arm against left, muscle pain after exercise, and what to do when six weeks of resting it has changed nothing.
What causes pain in the upper arm between the shoulder and the elbow?
Upper arm pain between the shoulder and the elbow is most often referred from the shoulder: rotator cuff tendinopathy or a tear, impingement, or a frozen shoulder, all felt on the outer upper arm, not at the joint. Biceps tendonitis hurts at the front. After a fall, a humerus fracture. Less often, a nerve from the neck or the heart.1,2
Key takeaways
- Pain on the outer upper arm that is worst reaching overhead, reaching behind you and lying on that side is usually the rotator cuff, felt where the deltoid attaches rather than at the shoulder.
- Pain at the front of the shoulder running down the front of the arm, worse lifting palm-up or carrying, is usually biceps tendonitis.
- Severe upper arm pain after a fall, with swelling and bruising that tracks toward the elbow, is a humerus fracture until an X-ray says otherwise.
- Pain in the upper arm with chest pressure, breathlessness, sweating or pain into the jaw is treated as the heart until proven otherwise. Call 995.
- Six weeks of rest that has changed nothing is the point to have the cuff and the neck tested, not to rest for six more.
First, the signs that mean a doctor, not this page
- Call 995 for upper arm pain with chest pressure or tightness, breathlessness, sweating, nausea or pain into the jaw, neck or back, whichever arm it is; for sudden arm weakness or numbness with a drooping face or slurred speech; or if the arm or hand is cold, white or blue.
- Go to the emergency department now if the arm is out of shape after a fall or crash, if you cannot lift or move it at all after an injury, if the hand is numb or weak after an injury, or if the arm is hot, red and swollen with a fever.
- See a doctor the same day for a fall onto the arm or shoulder with pain and swelling, which needs an X-ray, or for a sudden pop at the front of the shoulder or elbow followed by bruising and a new bulge in the arm muscle, which is a torn biceps tendon and a surgeon’s decision within days.
- See a doctor soon for pain in both upper arms at once, especially with stiff or swollen hands in the morning; for night pain that no position changes; for weight loss, fever or a history of cancer; for an arm that has become weak lifting it out to the side after an injury; for numbness or tingling that runs into the hand; or if nothing has changed after six weeks of a proper plan.
None of these? Then the rest of this page is for you.
Where it hurts and when tells you what it is
| Where and when | What it usually is | Who checks it first |
|---|---|---|
| Outer upper arm, a hand’s width below the shoulder. Worst reaching overhead, reaching behind, lying on it. An arc of pain partway up | Rotator cuff tendinopathy, a cuff tear, or impingement under the shoulder roof. The tendon hurts at the shoulder; the pain is felt lower down | A physiotherapist tests the cuff against resistance. A scan is a doctor’s call if the arm is weak |
| Front of the shoulder, running down the front of the arm. Worse lifting palm-up, carrying bags, pushing up from a chair | Biceps tendonitis, the long head of the tendon in its groove | A physiotherapist |
| The whole shoulder and upper arm, stiff in every direction, cannot turn the arm out to put a jacket on. Came on over weeks. Worse at night. Usually over 40 | Frozen shoulder | A physiotherapist. A doctor if you have diabetes and it is the first episode |
| After a fall or a blow. Severe, swollen, bruising that spreads toward the elbow over days. Cannot lift the arm | A humerus fracture, at the top of the bone or along the shaft | A doctor and an X-ray first |
| Outer arm with neck pain or stiffness, tingling into the thumb or index finger, worse looking up or turning the head | A nerve root irritated in the neck, usually C5 or C6 | A physiotherapist. A doctor if there is weakness |
| Deep at the front of the elbow and the lower front of the arm, after pulling, rowing or carrying | The brachialis muscle, not the biceps | A physiotherapist |
Why the pain is in the arm when the problem is in the shoulder
The rotator cuff tendons, the shoulder capsule and the bursa all send their pain to the same patch of skin on the outer upper arm, where the deltoid muscle attaches, because they share a nerve supply with it. Rotator cuff tendinopathy typically refers pain to the outer upper arm rather than the shoulder itself, which is why pressing the shoulder finds nothing and pressing the arm finds nothing, and lifting the arm finds everything.1 The clue is what the pain does, not where you feel it. Pain that changes with reaching, lifting and lying on the arm is a shoulder, wherever it lands. Pain that changes with turning the head is a neck. Pain that changes with walking up stairs is not a shoulder at all; see the 995 line.
Right arm, left arm, both arms
Pain in the upper right arm follows the side you reach, lift, mouse and sleep on, so for most right-handers it is the right rotator cuff or biceps, loaded more and rested less. Pain in the upper left arm in a left-hander is the same story. Both arms at once is different: either a neck that refers to both sides, a systemic cause such as an inflammatory arthritis or a thyroid problem, or, in older adults, a stiff shoulder on each side that started months apart. Both arms is a doctor’s question first. And on either side, upper arm pain that arrives with chest pressure, breathlessness or sweating is the heart until proven otherwise. That is a 995 call, not a search.
Upper arm muscle pain after exercise
A dull ache through the whole upper arm that starts a day after a new or heavy workout, peaks at 48 hours and fades by day four or five is delayed-onset muscle soreness. It is sore to squeeze, it eases as you warm up, and it needs nothing but time and the next workout kept lighter. A sharp pain during the lift, a pop, a bruise appearing over the following days, or a lump that was not there before is a tear and belongs in the same-day doctor line. Soreness that has lasted two weeks is not soreness.
Should you exercise it, or rest it?
Depends entirely on which structure it is, which is the problem with the exercise videos. A cuff tendon wants load, built up carefully, and gets worse with weeks of rest. A frozen shoulder in its painful stage wants the irritating stretches taken away, not added. A fracture wants a sling and an X-ray. A biceps tendon wants the palm-up carrying reduced and the shoulder blade strengthened. The same pendulum exercise helps one of those and sets another back by a fortnight. Which one you have is a test, not a guess, and it takes a physiotherapist about ten minutes.
Six weeks of resting it, and the seat belt still gets you
The thinking goes: it is a pulled muscle, rest it and it will settle.
So you rested it. Six weeks. You reach for the seat belt with the other hand now. You sleep on one side, badly. The hair gets washed with the elbow tucked in. The top cupboard has been quietly reorganized, and the badminton racquet has not left the bag since September. You have not told anyone it is still there, because it is only an arm, and nothing happened to it.
Rest did nothing because nothing was torn by a single event; a cuff tendon that has started to hurt is one that is no longer coping with the load it is given, and taking the load away for six weeks leaves it weaker and no more able to cope when the load comes back. The tendon recovers by being loaded, a little more each week, in the directions it has stopped tolerating, with the shoulder blade muscles behind it doing their share. Six weeks of waiting has told you what six more will do. The trip in January, with the suitcase in the overhead locker, is eight weeks away.
Has anyone tested the rotator cuff against resistance, side to side? Measured how far the arm turns out against the other one? Checked whether turning your head changes the arm? Watched the shoulder blade move while the arm goes up? If not, nobody yet knows whether this is a cuff, a biceps tendon, a stiffening capsule or a neck, and each needs a different plan.
What a physiotherapist does with it
Finding the real problem is half the battle. Treating it is the other half.
At the Assessment & Treatment, a physiotherapist asks where it is and what sets it off, in your words, then tests what the arm has been missing: each rotator cuff tendon against resistance, side to side; how far the arm lifts, turns out and reaches behind, measured against the other arm; the biceps tendon in its groove; how the shoulder blade moves as the arm rises; and the neck, because it refers here. If the pattern points to a fracture, a torn tendon with a bulge, both arms, or anything in the doctor list, we say so and write to your doctor. X-rays, scans, injections and surgery are a doctor’s decision.
If it is the cuff, the biceps tendon, a stiffening shoulder or the neck, most of the 45 minutes is treatment: hands-on work for the joint and the muscles around it, movement to the end of range, then the loading the tendon has been missing, measured at each review. You leave knowing which stage you are in, what is limiting the arm, and a written plan. The pages on rotator cuff injury, biceps tendonitis, frozen shoulder and a pinched nerve in the neck each cover one cause in full, and physiotherapy for shoulder pain covers the program.
Every appointment is one to one with your physiotherapist for the full 45 minutes, at five clinics: Orchard, Tampines, Serangoon, Tanjong Pagar and Jurong East. Bring any X-ray or scan report you have.
Questions about upper arm pain
Why does my upper arm hurt between the shoulder and the elbow?
Most often because of a shoulder problem that refers pain down the arm: rotator cuff tendinopathy or a tear, impingement, or a frozen shoulder, all felt on the outer upper arm where the deltoid attaches. Biceps tendonitis hurts at the front of the arm. After a fall, a fracture of the humerus. A pinched nerve in the neck and, rarely, the heart can also be felt here.
Why is my upper arm pain worse at night?
Lying on the shoulder compresses the rotator cuff tendons and bursa, and lying on the other side lets the arm hang forward and stretch them, so cuff problems and frozen shoulder are often worst in bed. Night pain that no position eases, or that wakes you every night with no daytime pattern, should be checked by a doctor.
Why does my upper arm hurt when I lift it?
Pain on the outer upper arm as the arm lifts out to the side or overhead, often through an arc partway up, usually points to the rotator cuff tendons or the bursa being loaded or pinched under the shoulder roof. A physiotherapist tests each tendon against resistance to find which one it is.
What causes pain in both upper arms?
Pain in both upper arms at the same time is less often a shoulder problem and more often a neck referring to both sides, an inflammatory condition such as rheumatoid arthritis or polymyalgia rheumatica, or a thyroid problem. It is a question for a doctor first, who may arrange blood tests, with physiotherapy afterward if the shoulders are involved.
Is upper arm pain a sign of a heart attack?
It can be. Upper arm pain with chest pressure or tightness, breathlessness, sweating, nausea or pain into the jaw or back is treated as a heart attack until proven otherwise, in either arm. Call 995. Upper arm pain that changes with lifting, reaching or lying on the arm and comes with no chest symptoms is almost always the shoulder.
How long does upper arm pain take to go away?
Muscle soreness after exercise settles within a week. Rotator cuff and biceps tendon problems usually improve over six to twelve weeks of graded loading, with durations varying by person. A frozen shoulder runs a course of a year or more. A fracture needs weeks for the bone and months for the strength. Pain that has not changed after six weeks should be assessed rather than rested further.
Six weeks in, and the seat belt still goes to the other hand? Get Assessed & Treated, and leave knowing whether it is the cuff, the biceps, the capsule or the neck, what the arm can take today, and what the next stage asks of it.
Sources: 1. Bayam L, Ahmad MA, Naqui SZ, Chouhan A, Funk L. Pain mapping for common shoulder disorders. Am J Orthop. 2011;40(7):353-358. 2. Mitchell C, Adebajo A, Hay E, Carr A. Shoulder pain: diagnosis and management in primary care. BMJ. 2005;331(7525):1124-1128.
Upper arm pain after a fall is a different question: see humerus fracture. Pain at the back of the shoulder and armpit is often teres major or teres minor.
Where are you with this right now?
1. It is settling on its own
Most injuries and most flare-ups settle over weeks with sensible load management and a return to normal movement. Improvement is judged over a month, not over a day, and good days and bad days inside that are usual. If you are doing more this month than last, and sleeping better, it is behaving the way it should. You do not need us for this, and we would rather say so.
2. It has stopped improving
You reach for the seat belt with the other hand now. You sleep on one side. The top cupboard has been quietly reorganized.
What our patients say
Google reviews from our clinics in Singapore.
Pain is the first thing to leave. Movement and strength are the last things trained back, and most people stop before that part is done. That is the gap worth measuring, and it is not measured by how you feel on the day.
The Stalled Recovery Review is three appointments over three weeks with the same therapist, because what a joint does under load cannot be read in one visit. The first finds what is limiting it. The next two measure how it responds. $690, nett, no GST, which is three appointments at $230.
3. You have had surgery, or you have a date
Recovery after an operation has a shape, and knowing which stage you are in tells you whether you are on it. If you had shoulder surgery, see the Rotator Cuff Repair Recovery Program or the Proximal Humerus Fracture Recovery Program. For any other operation, see all the recovery programs, hand and physiotherapy.
All of it runs on the same four stages. The Phoenix Recovery Protocol explains what each stage works on and what you have to meet to move up. No referral needed to start.
Next step
Find out which stage you are in
Pain is the first thing to leave. Movement and strength are the last things trained back, and most people stop before that part is done. One Assessment and Treatment is a single 45-minute appointment at $230, nett, no GST. Your therapist finds what is actually limiting you, treats it in the same appointment, and you leave with your current stage and a written plan.
Prefer to phone? Each of our five clinics has its own number on the clinics page. No referral needed to book.
Related reading
- Rotator Cuff Injury: Why Your Shoulder Hurts Overhead, and Worse at Night
- Biceps Tendonitis: Front of Shoulder Pain When You Lift, and What Helps
- Frozen shoulder: why it hurts most at night, and what helps
- Shoulder Impingement Syndrome Exercises
- Proximal humerus fracture
- Brachialis pain and strain
- Cervical Radiculopathy: A Pinched Nerve in Your Neck, Explained Properly
- Shoulder Pain After Waking Up: Causes and What Helps
- Physiotherapy for Shoulder Pain
- The Phoenix Recovery Protocol, and the four stages
- All recovery programs, hand and physio
Where we are
Clinics across Singapore
ORCHARD
400 Orchard Road #12-12
Orchard Towers, S238875
NS22 Orchard MRT
Physiotherapy and hand therapy in Orchard →
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9 Tampines Grande #01-20
Asia Green, S528735
EW2DT32 Tampines MRT
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WhatsApp 8780 9608SERANGOON
265 Serangoon Central Drive #04-269
S550265 · Lift C only
NE12CC13 Serangoon MRT
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WhatsApp 8892 4121TANJONG PAGAR
10 Anson Road #02-77A
International Plaza, S079903
EW15 Tanjong Pagar MRT
Physiotherapy and hand therapy in Tanjong Pagar →
WhatsApp 8227 7074JURONG EAST
2 Venture Drive #02-02
Vision Exchange, S608526
NS1EW24 Jurong East MRT
Physiotherapy and hand therapy in Jurong East →
WhatsApp 8242 7340