Angina is chest pain that happens when not enough blood flows to your heart muscle. Angina feels like pressure or tightness in your chest. It is usually brought on by activity or stress and can go away when the stressful activity stops.

Nitroglycerin relaxes blood vessels, allowing more blood and oxygen to flow through them.

Heart attack happens when an artery that feeds your heart muscle becomes blocked with plaque (fatty deposits) or by a clot. When the blood cannot flow to the heart, damage or death to the heart muscle may occur.

These feelings can signal a heart attack:

• a tightening, pressure, squeezing or aching in your chest or arms
• a feeling of indigestion
• a feeling of fullness
• a sharp burning or cramping pain
• an ache, weakness or numbness that begins in or spreads to your neck, jaw, throat, teeth, back, shoulder or back of your arms
• a discomfort in your neck or upper back, particularly between your shoulder blades.

These feelings can signal heart attack especially if they occur with:

• difficulty breathing or shortness of breath
• nausea or vomiting
• cold sweats
• paleness
• generalized weakness or severe fatigue
• anxiety
• strong, rapid heartbeats or palpitations
• dizziness.

Pain from angina is often relieved by rest and nitroglycerin.

Heart attack pain usually lasts after 15 minutes of resting. A nitroglycerin tablet may only provide temporary or incomplete relief. If the pain is relieved, it usually returns.

If you feel symptoms of angina, follow these steps unless your health care provider has given you other instructions:

• Take one nitroglycerin tablet or use one nitroglycerin spray. Sit for 5 minutes.
• If the angina goes away, rest for a while, then continue your normal routine.
• If the angina does not go away or gets worse, call 911 right away. Do not delay. Do not drive yourself to a hospital emergency room or urgent care.

If you have any heart attack warning signs, call 911 right away. Then, the American Heart Association recommends taking an aspirin as soon as the warning signs of a heart attack occur. Research shows that taking an aspirin when heart attack symptoms start significantly improves chances of survival. Do not take an aspirin if you have an allergy to aspirin.