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, herbal remedies, or 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.

Babies can quickly get dehydrated when they lose fluids because of problems like vomiting or fever.

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

• The baby may be fussy or cranky (mild dehydration), or the baby may be very sleepy and hard to wake up (severe dehydration).
• The baby may have a little less urine than usual (mild dehydration), or the baby may not be urinating at all (severe dehydration).

You can get dehydrated when you lose a lot of fluids because of problems like vomiting or fever.

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

• You may feel tired and edgy (mild dehydration), or you may feel weak, not alert, and not able to think clearly (severe dehydration).
• You may pass less urine than usual (mild dehydration), or you may not be passing urine at all (severe dehydration).

Severe dehydration means:

• The baby may be very sleepy and hard to wake up.
• The baby may have a very dry mouth and very dry eyes (no tears).
• The baby may have no wet diapers in 12 or more hours.

Moderate dehydration means:

• The baby may have no wet diapers in 6 hours.
• The baby may have a dry mouth and dry eyes (fewer tears than usual).

Mild dehydration means:

• The baby may pass a little less urine than usual.

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).

Symptoms of difficulty breathing in a baby or young child can range from mild to severe. For example:

• The child may be breathing a little faster than usual (mild difficulty breathing), or the child may be having so much trouble that the nostrils are flaring and the belly is moving in and out with every breath (severe difficulty breathing).
• The child may seem a little out of breath but is still able to eat or talk (mild difficulty breathing), or the child may be breathing so hard that he or she cannot eat or talk (severe difficulty breathing).

Sudden drooling and trouble swallowing can be signs of a serious problem called epiglottitis. This problem can happen at any age.

The epiglottis is a flap of tissue at the back of the throat that you can't see when you look in the mouth. When you swallow, it closes to keep food and fluids out of the tube (trachea) that leads to the lungs. If the epiglottis becomes inflamed or infected, it can swell and quickly block the airway. This makes it very hard to breathe.

The symptoms start suddenly. A person with epiglottitis is likely to seem very sick, have a fever, drool, and have trouble breathing, swallowing, and making sounds. In the case of a child, you may notice the child trying to sit up and lean forward with his or her jaw forward, because it's easier to breathe in this position.

Many prescription and nonprescription medicines can trigger an allergic reaction and cause a fever. A few examples are:

• Antibiotics.
• Barbiturates, such as phenobarbital.
• Aspirin, if you take too much.

Fever can be a symptom of almost any type of infection. Symptoms of a more serious infection may include the following:

• Skin infection: Pain, redness, or pus
• Joint infection: Severe pain, redness, or warmth in or around a joint
• Bladder infection: Burning when you urinate, and a frequent need to urinate without being able to pass much urine
• Kidney infection: Pain in the flank, which is either side of the back just below the rib cage
• Abdominal infection: Belly pain

Symptoms of heatstroke may include:

• Feeling or acting very confused, restless, or anxious.
• Trouble breathing.
• Sweating heavily, or not sweating at all (sweating may have stopped).
• Skin that is red, hot, and dry, even in the armpits.
• Passing out.
• Seizure.
• Nausea and vomiting.

Heatstroke occurs when the body can't control its own temperature and body temperature continues to rise.

Severe dehydration means:

• The child's mouth and eyes may be extremely dry.
• The child may pass little or no urine for 12 or more hours.
• The child may not seem alert or able to think clearly.
• The child may be too weak or dizzy to stand.
• The child may pass out.

Moderate dehydration means:

• The child may be a lot more thirsty than usual.
• The child's mouth and eyes may be drier than usual.
• The child may pass little or no urine for 8 or more hours.
• The child may feel dizzy when he or she stands or sits up.

Mild dehydration means:

• The child may be more thirsty than usual.
• The child may pass less urine than usual.

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.

Temperature varies a little depending on how you measure it. For children up to 11 years old, here are the ranges for high, moderate, and mild according to how you took the temperature.

Oral (by mouth), ear, or rectal temperature

• High: 104° F (40° C) and higher
• Moderate: 100.4° F (38° C) to 103.9° F (39.9° C)
• Mild: 100.3° F (37.9° C) and lower

A forehead (temporal) scanner is usually 0.5° F (0.3° C) to 1° F (0.6° C) lower than an oral temperature.

Armpit (axillary) temperature

• High: 103° F (39.5° C) and higher
• Moderate: 99.4° F (37.4° C) to 102.9° F (39.4° C)
• Mild: 99.3° F (37.3° C) and lower

Note: For children under 5 years old, rectal temperatures are the most accurate.

Sudden tiny red or purple spots or sudden bruising may be early symptoms of a serious illness or bleeding problem. There are two types.

Petechiae (say "puh-TEE-kee-eye"):

• Are tiny, flat red or purple spots in the skin or the lining of the mouth.
• Do not turn white when you press on them.
• Range from the size of a pinpoint to the size of a small pea and do not itch or cause pain.
• May spread over a large area of the body within a few hours.
• Are different than tiny, flat red spots or birthmarks that are present all the time.

Purpura (say "PURR-pyuh-ruh" or “PURR-puh-ruh”):

• Is sudden, severe bruising that occurs for no clear reason.
• May be in one area or all over.
• Is different than the bruising that happens after you bump into something.

You can use a small rubber bulb (called an aspirating bulb) to remove mucus from your baby's nose or mouth when a cold or allergies make it hard for the baby to eat, sleep, or breathe.

To use the bulb:

1. Put a few saline nose drops in each side of the baby's nose before you start.
2. Position the baby with his or her head tilted slightly back.
3. Squeeze the round base of the bulb.
4. Gently insert the tip of the bulb tightly inside the baby's nose.
5. Release the bulb to remove (suction) mucus from the nose.

Don't do this more than 5 or 6 times a day. Doing it too often can make the congestion worse and can also cause the lining of the nose to swell or bleed.

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.

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.

If you're not sure if a child's fever is high, moderate, or mild, think about these issues:

With a high fever:

• The child feels very hot.
• It is likely one of the highest fevers the child has ever had.

With a moderate fever:

• The child feels warm or hot.
• You are sure the child has a fever.

With a mild fever:

• The child may feel a little warm.
• You think the child might have a fever, but you're not sure.

A baby that is extremely sick:

• May be limp and floppy like a rag doll.
• May not respond at all to being held, touched, or talked to.
• May be hard to wake up.

A baby that is sick (but not extremely sick):

• May be sleepier than usual.
• May not eat or drink as much as usual.

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.

Pain in children 3 years and older

• Severe pain (8 to 10): The pain is so bad that the child can't stand it for more than a few hours, can't sleep, and can't do anything else except focus on the pain. No one can tolerate severe pain for more than a few hours.
• Moderate pain (5 to 7): The pain is bad enough to disrupt the child's normal activities and sleep, but the child can tolerate it for hours or days.
• Mild pain (1 to 4): The child notices and may complain of the pain, but it is not bad enough to disrupt his or her sleep or activities.

Symptoms of serious illness in a baby may include the following:

• The baby is limp and floppy like a rag doll.
• The baby doesn't respond at all to being held, touched, or talked to.
• The baby is hard to wake up.

Symptoms of serious illness may include:

• A severe headache.
• A stiff neck.
• Mental changes, such as feeling confused or much less alert.
• Extreme fatigue (to the point where it's hard for you to function).
• Shaking chills.