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.

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.

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.

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

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.

Abnormal bleeding means any heavy or frequent bleeding or any bleeding that is not normal for you. Examples of abnormal bleeding include:

• Nosebleeds.
• Vaginal bleeding that is different (heavier, more frequent, at a different time of month) than what you are used to.
• Rectal bleeding and bloody stools.
• Bloody or pink urine.
• Gums that bleed easily when you eat or gently brush your teeth.

When you have abnormal bleeding in one area of your body, it's important to think about whether you have been bleeding anywhere else. This can be a symptom of a more serious health problem.

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.

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.

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.

Many prescription and non-prescription medicines can cause a rash. A few common examples are:

• Antibiotics.
• ASA, ibuprofen (Advil, Motrin), and naproxen (Aleve).
• Pain medicines, such as codeine.
• Seizure medicines.

Symptoms of a severe allergic reaction can start within minutes of eating or being exposed to an allergen. While symptoms usually occur within 2 hours, in rare cases the time frame can vary up to several hours after exposure. Do not ignore early symptoms. When a reaction begins, it is important to respond right away.

• Skin: hives, swelling (face, lips, tongue), itching, warmth, redness
• Respiratory (breathing): coughing, wheezing, shortness of breath, chest pain or tightness, throat tightness, hoarse voice, nasal congestion or hay fever-like symptoms (runny, itchy nose and watery eyes, sneezing), trouble swallowing
• Gastrointestinal (stomach): nausea, pain or cramps, vomiting, diarrhea
• Cardiovascular (heart): paler than normal skin colour/blue colour, weak pulse, passing out, dizziness or lightheadedness, shock
• Other: anxiety, sense of doom (the feeling that something bad is about to happen), headache, uterine cramps, metallic taste

A severe reaction can take place without hives, so make sure to look out for all of the signs of an allergic reaction.