Heart attacks can cause left arm pain because of a phenomenon called referred pain.
Shared nerve pathways between the heart and left arm cause the brain to misinterpret pain signals.
Pain may also spread to the jaw, neck, shoulder, upper back, or even the right arm.
Some heart attacks occur without chest pain, especially in women, older adults, and people with diabetes.
Persistent arm pain with chest discomfort, breathlessness, or sweating requires immediate emergency medical attention.
Many people know that heart attacks cause chest pain. But why do so many people also experience pain in the left arm? Surprisingly, the arm itself is usually not injured. Instead, the brain misinterprets pain signals traveling through shared nerve pathways, a phenomenon known as referred pain.
Although chest pain remains the most common symptom of a heart attack, many people also experience discomfort in the left shoulder or arm, jaw, neck, upper back, or upper abdomen. Understanding why this happens can help people recognize the warning signs of a heart attack earlier and seek timely medical care.
Rather than spreading through the arm, pain signals from the injured heart travel along shared neural pathways and converge with sensory nerves from the chest and upper limb within the spinal cord. As a result, the brain may mistakenly perceive the pain as originating from the left arm instead of the heart.1,2
Understanding this neuroanatomical mechanism is essential for both healthcare professionals and the public, as recognizing referred pain can facilitate the early identification and timely treatment of myocardial infarction.
A heart attack, or myocardial infarction, occurs when blood flow to part of the heart is blocked, depriving the heart muscle of oxygen. If blood flow is not restored quickly, the affected muscle begins to die.3,4
As the injured heart muscle releases chemical signals, pain-sensitive nerve endings are activated, sending pain messages to the spinal cord through visceral sensory nerves.1
Unlike pain from the skin or muscles, heart pain is visceral, making it difficult to pinpoint. It is often felt as pressure or tightness in the chest and may also spread to the left arm, shoulder, jaw, neck, upper back, or upper abdomen.
Some people, especially women, older adults, and those with diabetes, may experience little or no chest pain.
The heart is situated in the mediastinum, the central part of the chest, extending between the third and sixth costal cartilages. From this location, it pumps oxygen-rich blood to the rest of the body. Interestingly, pain from the heart is not always felt where the organ is located.5
But why does a problem in the heart cause pain in the arm? The answer lies in a fascinating phenomenon known as referred pain.
During a heart attack, the damaged heart muscle generates pain signals, yet the brain may perceive that pain as originating from the left shoulder, arm, jaw, or neck rather than from the heart itself. This phenomenon is known as referred pain.
Referred pain is defined as pain perceived at a location different from its actual source, despite the absence of injury or disease at the site where the pain is felt.2 It is a common feature of pain arising from internal organs.
The most accepted explanation is the convergence-projection theory. Pain signals from the heart and sensory signals from the skin and muscles meet on the same nerve cells in the spinal cord.1,2 Because the brain is more familiar with signals from the skin than from internal organs, it mistakenly assumes the pain is coming from the body surface instead of the heart.
The answer lies in the segmental organization of the nervous system.
Pain fibers from the heart primarily enter the spinal cord at T1 to T5, where they converge with somatic sensory neurons receiving input from:
the left anterior chest wall,
the left shoulder,
the medial aspect of the left upper arm,
and portions of the forearm.
These somatic regions share the same spinal segments as the heart. As a result, activation of cardiac visceral afferents is frequently interpreted by the brain as pain arising from these body regions.
One of the nerves supplying the inner part of the upper arm shares the same upper thoracic spinal cord segments that receive pain signals from the heart. Because these signals converge within the spinal cord, the brain may mistakenly identify the arm as the source of the pain instead of the heart.
More specifically, the medial cutaneous nerve of the arm and the intercostobrachial nerve (T2) contribute to sensory innervation of the medial upper arm. Since these nerves are associated with the same upper thoracic spinal segments that receive cardiac visceral afferents, discomfort is commonly perceived along the inner aspect of the left arm, a classic feature of myocardial infarction.¹˒⁵
In simple terms: The heart and the left arm send their pain messages through some of the same nerve pathways. Since these messages arrive along the same route, the brain can get confused and assume the pain is coming from the arm instead of the heart.
Although the left arm is the most recognizable site of radiation, it is not the only one. Depending on which spinal neurons are activated and individual variations in neural processing, patients may instead experience pain in the neck, jaw, shoulder, upper back, or upper abdomen.
Although the left arm is classically associated with myocardial infarction, pain may also radiate to the right arm or even involve both arms simultaneously.
Several clinical guidelines now recognize pain in either arm as a possible symptom of acute coronary syndrome, emphasizing that right-sided arm pain should never be dismissed when accompanied by other features of a heart attack.3,4
Perhaps the most challenging presentations are silent or atypical myocardial infarctions, in which patients experience little or no chest discomfort. Instead, they may report symptoms such as:
unusual fatigue,
shortness of breath,
nausea or vomiting,
cold sweats,
dizziness,
jaw pain,
upper back pain,
or isolated arm discomfort.
These atypical presentations are more frequently observed in women, older adults, and individuals with diabetes mellitus, although they can occur in anyone.3,4
The reasons for these differences are likely multifactorial and may include variations in neural pathways, pain perception, autonomic function, and associated medical conditions. Because symptoms are often subtle, patients may mistake them for indigestion, muscle strain, or fatigue, delaying life-saving treatment.
Left arm pain is not always a medical emergency, but it should never be ignored when it occurs together with symptoms suggestive of a heart attack. Seek immediate emergency medical care or call your local emergency medical services if left arm pain is accompanied by: ³˒⁴
central chest pressure, tightness, or pain,
shortness of breath or difficulty breathing,
cold sweats,
nausea or vomiting,
dizziness, light-headedness, or fainting,
sudden unexplained weakness,
pain spreading to the jaw, neck, shoulder, or back.
Healthcare organizations such as the American Heart Association advise calling emergency medical services rather than driving yourself to the hospital if you think you or someone else may be having a heart attack, as emergency responders can begin treatment on the way to the hospital.⁶˒⁷
No. Left arm pain can have many causes, and most episodes are not due to a heart attack. Depending on the location, severity, and associated symptoms, arm pain may result from:
muscle strain or overuse,
shoulder injuries such as rotator cuff disorders,
cervical radiculopathy (a pinched nerve in the neck),
arthritis affecting the shoulder or cervical spine,
peripheral nerve compression or irritation.
However, sudden unexplained left arm pain occurring together with chest discomfort, breathlessness, sweating, nausea, dizziness, or pain radiating to the jaw or back should always be treated as a medical emergency until proven otherwise.³˒⁴
No single symptom can confirm or exclude a heart attack. Left arm pain is an important clinical clue, but it should always be interpreted alongside other symptoms such as:
central chest pressure or tightness,
shortness of breath,
sweating,
nausea,
dizziness,
pain radiating to the jaw, neck, shoulder, or back.
Similarly, the absence of left arm pain does not rule out myocardial infarction. Healthcare professionals evaluate the overall pattern of symptoms, medical history, physical examination findings, electrocardiography (ECG), and cardiac biomarkers before making a diagnosis.
For the general public, the key message is simple: persistent chest discomfort or unexplained pain in the arm, jaw, neck, or upper back, particularly when accompanied by breathlessness or sweating, should always prompt immediate medical evaluation.
Referred pain is more than an anatomy concept. It reminds us that heart attacks do not always present with chest pain alone. Sometimes, discomfort in the arm, jaw, neck, shoulder, or upper back may be the body's first warning sign. Recognizing these symptoms early and seeking immediate medical care can reduce delays in diagnosis and treatment, improving the chances of survival and recovery.
Whether you are a healthcare professional or a member of the public, understanding referred pain and recognizing these warning signs can encourage faster medical attention, earlier treatment, and ultimately help save lives.
Why is left arm pain associated with heart attacks?
Pain fibers from the heart enter the spinal cord at the same upper thoracic segments that receive sensory information from the left arm and shoulder. Because these signals converge on shared neurons, the brain may mistakenly interpret heart pain as coming from the arm, producing referred pain.¹˒²
Why doesn't everyone get left arm pain during a heart attack?
The symptoms of a heart attack vary from person to person. Individual differences in nerve pathways, pain perception, the location of the heart attack, and underlying medical conditions all influence how pain is experienced.³˒⁴
Can anxiety cause left arm pain?
Yes. Anxiety and panic attacks can sometimes cause chest discomfort, muscle tension, tingling, or pain in the left arm. However, because heart attacks and anxiety can share similar symptoms, new or unexplained arm pain accompanied by chest discomfort, breathlessness, sweating, or nausea should always be evaluated urgently by a healthcare professional.³˒⁴
1. Foreman, Robert D., Kenneth M. Garrett, and Robert W. Blair. 2015. "Mechanisms of Cardiac Pain." Comprehensive Physiology 5 (2): 929–960. https://doi.org/10.1002/j.2040-4603.2015.tb00616.x.
2. Jin, Q., Y. Chang, C. Lu, L. Chen, and Y. Wang. 2023. "Referred Pain: Characteristics, Possible Mechanisms, and Clinical Management." Frontiers in Neurology 14: 1104817. https://doi.org/10.3389/fneur.2023.1104817.
3. Mayo Clinic. 2026. "Heart Attack: Symptoms and Causes." https://www.mayoclinic.org/diseases-conditions/heart-attack/symptoms-causes/syc-20373106.
4. Cleveland Clinic. 2026. "Heart Attack (Myocardial Infarction)." https://my.clevelandclinic.org/health/diseases/16818-heart-attack-myocardial-infarction.
5. Volpe, John K., and Amgad N. Makaryus. 2023. Anatomy, Thorax, Heart and Pericardial Cavity. In StatPearls [Internet]. Treasure Island, FL: StatPearls Publishing. Updated July 25, 2023. Accessed July 18, 2026. NCBI Bookshelf
6. American Heart Association. "Heart Attack Symptoms, Risk, and Recovery." https://www.heart.org/en/health-topics/heart-attack
7. American Heart Association. "Warning Signs of a Heart Attack." https://www.heart.org/en/health-topics/heart-attack/warning-signs-of-a-heart-attack