Out of the one million Americans who have a heart attack this year, about 150,000 will die from the event. Even more concerning is the fact that about half of people who suffer a heart attack don’t even know what’s happening. They confuse the symptoms for something else, don’t take them seriously, and potentially abstain from even seeking medical attention.

In movies, heart attacks are often portrayed by a panicked man clutching his chest and exclaiming, “I’m having a heart attack!” But in reality, a heart attack doesn’t always manifest in such a dramatic fashion. Because the situation might not become instantly clear to the patient or onlookers, we should all educate ourselves on the signs of a heart attack.

It’s not always pain. You might picture a heart attack as a sudden, severe pain in your chest. But sometimes a cardiac event will manifest as a “discomfort” or “odd feeling” or simply an ache that is more obnoxious than severely painful. A good rule of thumb to follow is that if it feels different from anything you’ve felt before, get it checked out.

You might think you’re getting sick. Some heart attack victims report feeling feverish or sweaty just before the event happens. You might feel as though you’re coming down with the flu, and yet the thermometer does not register an actual fever.

Heart attack can mimic indigestion. Some patients report that they first thought they were suffering indigestion; a sudden feeling of fullness or pressure in your chest might signal the beginning of a heart attack.

It’s not just your chest. While a feeling of discomfort, pressure, or pain in the chest is a hallmark sign of a heart attack, you might experience other symptoms. Pain in the shoulders is common (particularly the right shoulder) and even in the jaw.

You might think you’re “okay” because you can still function. Due to dramatic media portrayals of heart attacks, we picture people dropping to the ground during an event. But some heart attack patients are still walking around, conducting their normal daily activities while it is happening. They might feel pressure or the other symptoms listed above, but they aren’t so debilitating that they suspect a heart attack.

The bottom line is that if you feel any sort of discomfort, pain, pressure, or another odd feeling that concerns you, it’s always better to be safe rather than sorry. Proceed to the emergency room to get checked out, or call 911 if symptoms are severe.