Many things can affect how your body responds to a symptom and what kind of care you may need. These include:

• Your age. Babies and older adults tend to get sicker quicker.
• Your overall health. If you have a condition such as diabetes, HIV, cancer, or heart disease, you may need to pay closer attention to certain symptoms and seek care sooner.
• Medicines you take. Certain medicines, herbal remedies, and supplements can cause symptoms or make them worse.
• Recent health events, such as surgery or injury. These kinds of events can cause symptoms afterwards or make them more serious.
• Your health habits and lifestyle, such as eating and exercise habits, smoking, alcohol or drug use, sexual history, and travel.

Heartbeat changes can include:

• A faster or slower heartbeat than is normal for you. This would include a pulse rate of more than 120 beats per minute (when you are not exercising) or less than 50 beats per minute (unless that is normal for you).
• A heart rate that does not have a steady pattern.
• Skipped beats.
• Extra beats.

Many things can make the heart beat faster or slower than usual. Some common examples are:

• Stress.
• Pain.
• Illness or fever.
• Dehydration.
• Exercise.
• Panic attacks.
• Stimulants, such as caffeine and nicotine.
• Medicine side effects.

Shock is a life-threatening condition that may quickly occur after a sudden illness or injury.

Adults and older children often have several symptoms of shock. These include:

• Passing out (losing consciousness).
• Feeling very dizzy or lightheaded, like you may pass out.
• Feeling very weak or having trouble standing.
• Not feeling alert or able to think clearly. You may be confused, restless, fearful, or unable to respond to questions.

Shock is a life-threatening condition that may occur quickly after a sudden illness or injury.

Babies and young children often have several symptoms of shock. These include:

• Passing out (losing consciousness).
• Being very sleepy or hard to wake up.
• Not responding when being touched or talked to.
• Breathing much faster than usual.
• Acting confused. The child may not know where he or she is.

Symptoms of a heart attack may include:

• Chest pain or pressure, or a strange feeling in the chest.
• Sweating.
• Shortness of breath.
• Nausea or vomiting.
• Pain, pressure, or a strange feeling in the back, neck, jaw, or upper belly, or in one or both shoulders or arms.
• Lightheadedness or sudden weakness.
• A fast or irregular heartbeat.

The more of these symptoms you have, the more likely it is that you’re having a heart attack. Chest pain or pressure is the most common symptom, but some people, especially women, may not notice it as much as other symptoms. You may not have chest pain at all but instead have shortness of breath, nausea, or a strange feeling in your chest or other areas.

Symptoms of difficulty breathing can range from mild to severe. For example:

• You may feel a little out of breath but still be able to talk (mild difficulty breathing), or you may be so out of breath that you cannot talk at all (severe difficulty breathing).
• It may be getting hard to breathe with activity (mild difficulty breathing), or you may have to work very hard to breathe even when you’re at rest (severe difficulty breathing).

Severe trouble breathing means:

• You cannot talk at all.
• You have to work very hard to breathe.
• You feel like you can’t get enough air.
• You do not feel alert or cannot think clearly.

Moderate trouble breathing means:

• It’s hard to talk in full sentences.
• It’s hard to breathe with activity.

Mild trouble breathing means:

• You feel a little out of breath but can still talk.
• It’s becoming hard to breathe with activity.

Severe trouble breathing means:

• The child cannot eat or talk because he or she is breathing so hard.
• The child’s nostrils are flaring and the belly is moving in and out with every breath.
• The child seems to be tiring out.
• The child seems very sleepy or confused.

Moderate trouble breathing means:

• The child is breathing a lot faster than usual.
• The child has to take breaks from eating or talking to breathe.
• The nostrils flare or the belly moves in and out at times when the child breathes.

Mild trouble breathing means:

• The child is breathing a little faster than usual.
• The child seems a little out of breath but can still eat or talk.

Many medicines and drugs can affect the rate and rhythm of the heart. A few examples are:

• Asthma medicines.
• Decongestants and cold medicines.
• Illegal drugs such as cocaine or amphetamines.
• Some heart and blood pressure medicines.
• Some medicines for depression and anxiety.
• Thyroid medicine.