The left arm is the one most often associated with heart attack pain or numbness, but either arm can be affected. Arm numbness by itself is not enough to tell what’s happening; if it comes with chest pressure, shortness of breath, sweating, nausea, or pain spreading to the jaw, back, or shoulder, treat it as an emergency.

What to watch for

  • Chest discomfort that lasts more than a few minutes or comes and goes.
  • Discomfort in one or both arms, the back, neck, jaw, or stomach.
  • Shortness of breath, cold sweat, nausea, or lightheadedness.
  • Arm weakness or numbness, especially if it appears suddenly with other symptoms.

Why the left arm

The left arm is more commonly mentioned because heart-related pain can radiate there, but numbness can also show up in the right arm or both arms.

What to do

If you or someone else has these symptoms, call emergency services right away rather than waiting to see if it passes.

TL;DR: Heart attacks most often affect the left arm , but either arm can go numb or hurt, and the safest response is urgent medical help if other warning signs are present.