In-depth

Causes

Heart arrhythmias

A heart arrhythmia is an abnormal heart rhythm. Arrhythmias can be a byproduct of damage to the heart from disease or age.

Complications

Low blood pressure (hypotension)

Low blood pressure (hypotension) can be a sign of good health or of a life-threatening condition. Find out more about hypotension's causes and treatment options.

Prevention

Heat and exercise

The outdoors and exercise seem to go together, but high temperatures and exercise can be a risky combination. Play it safe to prevent heat-related illnesses.

Risk factors

Dehydration and youth sports

When the heat is on, dehydration is a serious concern for young athletes. Prevention is the best bet.

Symptoms

Fatigue

Fatigue can signal many things. Here are some tips to help you decipher why you're wiped out and to regain your energy.

Headache

Most headaches aren't caused by a serious illness, but some could be a sign of a life-threatening condition.

Nausea and vomiting

Sick to your stomach? Nausea and vomiting usually pass quickly but sometimes result from long-term or serious conditions.

Tachycardia

Tachycardia, a rapid heart rate, is caused by an abnormality in your heart's electrical impulses. Tachycardia can cause serious complications, including sudden cardiac arrest.

Tests and diagnosis

Urinalysis

Urinalysis can be used to assess your overall health, detect a wide range of disorders, or monitor a medical condition or treatment.

Nov. 18, 2011