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, such as blood thinners (anticoagulants), medicines that suppress the immune system like steroids or chemotherapy, or natural health products 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.

Severe vomiting can mean that:

• You vomit more than 10 times in 24 hours.
• For at least 24 hours, you vomit every time you try to drink something.
• The vomit shoots out in large amounts and with great force.

If you have pain when you are breathing, you may be at immediate risk for a pulmonary embolism if you also have:

• Pain deep in one leg for no clear reason. This can be a sign of a blood clot in the leg (deep vein thrombosis) that could travel to the lungs.
• A history of problems with blood clots, such as deep vein thrombosis or a previous pulmonary embolism.

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.

Symptoms of a pulmonary embolism may include:

• Sudden shortness of breath.
• Sudden, sharp chest pain that may get worse when you breathe deeply or cough.
• A cough. The cough may bring up blood or pink, foamy mucus.
• Fast heart rate.
• Wheezing.
• Fainting.

Pain in adults and older children

• Severe pain (8 to 10): The pain is so bad that you can't stand it for more than a few hours, can't sleep, and can't do anything else except focus on the pain.
• Moderate pain (5 to 7): The pain is bad enough to disrupt your normal activities and your sleep, but you can tolerate it for hours or days. Moderate can also mean pain that comes and goes even if it's severe when it's there.
• Mild pain (1 to 4): You notice the pain, but it is not bad enough to disrupt your sleep or activities.

Pain in children under 3 years

It can be hard to tell how much pain a baby or toddler is in.

• Severe pain (8 to 10): The pain is so bad that the baby cannot sleep, cannot get comfortable, and cries constantly no matter what you do. The baby may kick, make fists, or grimace.
• Moderate pain (5 to 7): The baby is very fussy, clings to you a lot, and may have trouble sleeping but responds when you try to comfort him or her.
• Mild pain (1 to 4): The baby is a little fussy and clings to you a little but responds when you try to comfort him or her.

Several types of medicines can be used to treat pain.

Pain medicines may be over-the-counter (OTC) medicines—like acetaminophen (Tylenol) and non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin, ibuprofen, and naproxen. Ask your doctor which OTCs are safe for you to use.

Your doctor may prescribe other pain medicines. These may include some NSAIDs that aren't OTC medicines.

Opioids are strong medicines. They may be prescribed if your doctor thinks you may need them to relieve moderate to severe pain.

To avoid the risk of side effects from pain medicine, take the lowest dose that works to relieve your pain.

Take pain medicines exactly as prescribed or according to the label on the medicine bottle and box.

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 light-headed, 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.

Certain health conditions and medicines weaken the immune system's ability to fight off infection and illness. Some examples in adults are:

• Diseases such as diabetes, cancer, heart disease, and HIV/AIDS.
• Long-term alcohol and drug problems.
• Steroid medicines, which may be used to treat a variety of conditions.
• Chemotherapy and radiation therapy for cancer.
• Other medicines used to treat autoimmune disease.
• Medicines taken after organ transplant.
• Not having a spleen.

Certain health conditions and medicines weaken the immune system's ability to fight off infection and illness. Some examples in children are:

• Diseases such as diabetes, cystic fibrosis, sickle cell disease, and congenital heart disease.
• Steroid medicines, which are used to treat a variety of conditions.
• Medicines taken after organ transplant.
• Chemotherapy and radiation therapy for cancer.
• Not having a spleen.

Urinary tract infections may occur in the bladder or kidneys. Symptoms may include:

• Pain or burning when you urinate.
• A frequent need to urinate without being able to pass much urine.
• Pain in the flank, which is either side of the back just below the rib cage and above the waist.
• Blood in the urine.
• Fever.

Symptoms of infection may include:

• Increased pain, swelling, warmth, or redness in or around the area.
• Red streaks leading from the area.
• Pus draining from the area.
• A fever.

Neurological symptoms—which may be signs of a problem with the nervous system—can affect many body functions. Symptoms may include:

• Numbness, weakness, or lack of movement in your face, arm, or leg, especially on only one side of your body.
• Trouble seeing in one or both eyes.
• Trouble speaking.
• Confusion or trouble understanding simple statements.
• Problems with balance or coordination (for example, falling down or dropping things).
• Seizures.

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.
• Light-headedness or sudden weakness.
• A fast or irregular heartbeat.

For men and women, the most common symptom is chest pain or pressure. But women are somewhat more likely than men to have other symptoms, like shortness of breath, nausea, and back or jaw pain.

With severe bleeding, any of these may be true:

• Blood is pumping from the wound.
• The bleeding does not stop or slow down with pressure.
• Blood is quickly soaking through bandage after bandage.

With moderate bleeding, any of these may be true:

• The bleeding slows or stops with pressure but starts again if you remove the pressure.
• The blood may soak through a few bandages, but it is not fast or out of control.

With mild bleeding, any of these may be true:

• The bleeding stops on its own or with pressure.
• The bleeding stops or slows to an ooze or trickle after 15 minutes of pressure. It may ooze or trickle for up to 45 minutes.