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.

Temperature varies a little depending on how you measure it. For adults and children age 12 and older, these are the ranges for high, moderate, and mild, according to how you took the temperature.

Oral (by mouth) temperature

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

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

Ear temperature

• High: 40.5°C (104.9°F) and higher
• Moderate: 38.5°C (101.3°F) to 40.4°C (104.7°F)
• Mild: 38.5°C (101.3°F) and lower

Armpit (axillary) temperature

• High: 39.8°C (103.6°F) and higher
• Moderate: 37.8°C (100°F) to 39.7°C (103.5°F)
• Mild: 37.7°C (99.9°F) and lower

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.

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.

Symptoms of preterm labour may include:

• Mild or menstrual-like cramps, with or without diarrhea.
• A feeling of pressure in your pelvis or lower belly.
• A steady, dull ache in your lower back, pelvis, lower belly, or thighs.
• Changes in your vaginal discharge.
• Regular contractions for an hour. This means about 6 or more in 1 hour, even after you have had a glass of water and are resting.

Severe vaginal bleeding means you are soaking through your usual pads or tampons each hour for 2 or more hours. For most women, passing clots of blood from the vagina and soaking through their usual pads or tampons every hour for 2 or more hours is not normal and is considered severe. If you are pregnant: You may have a gush of blood or pass a clot, but if the bleeding stops, it is not considered severe.

Moderate bleeding means that you are soaking more than 1 pad or tampon in 3 hours.

Mild bleeding means that you are soaking less than 1 pad or tampon in more than 3 hours.

Minimal vaginal bleeding means "spotting" or a few drops of blood.

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

With a high fever:

• You feel very hot.
• It is likely one of the highest fevers you've ever had. High fevers are not that common, especially in adults.

With a moderate fever:

• You feel warm or hot.
• You know you have a fever.

With a mild fever:

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

Symptoms of a kidney infection may include:

• Pain in the flank, which is felt just below the rib cage and above the waist on one or both sides of the back.
• Fever or chills.
• Pain or burning when you urinate.
• A frequent urge to urinate without being able to pass much urine.
• Belly pain.

Symptoms of a bladder infection may include:

• Pain or burning when you urinate.
• A frequent urge to urinate without being able to pass much urine.
• Blood in the urine.

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.

During pregnancy, swelling that may be a sign of a more serious problem may include:

• Weight gain of 0.9 kg (2 lb) or more during a 24-hour period.
• New and increasing swelling, especially in your face, hands, or feet.
• Swelling in your feet that does not improve even after you lie on your side for several hours.

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:

• Your mouth and eyes may be extremely dry.
• You may pass little or no urine for 12 or more hours.
• You may not feel alert or be able to think clearly.
• You may be too weak or dizzy to stand.
• You may pass out.

Moderate dehydration means:

• You may be a lot more thirsty than usual.
• Your mouth and eyes may be drier than usual.
• You may pass little or no urine for 8 or more hours.
• You may feel dizzy when you stand or sit up.

Mild dehydration means:

• You may be more thirsty than usual.
• You may pass less urine than usual.

Signs that you are in labour include:

• Regular contractions for at least 1 hour. This means about 4 or more contractions in 20 minutes, or about 8 or more in a single hour.
• A sudden release of fluid from the vagina.

"Bloody show" is blood-tinged mucus that will pass out of the vagina for some women as the cervix begins to open (dilate) and thin (efface). On its own, however, this is not a definite sign that you are in labour.

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.

Symptoms of a vaginal infection may include:

• Vaginal itching.
• Vaginal discharge that is not normal for you.
• Vaginal odour.
• Red, irritated skin in the vaginal area.
• Pain when you urinate.
• Pain or bleeding when you have sex.