In-depth

Causes

Heart arrhythmias

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

Risk factors

Dehydration and youth sports

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

You Are ... The Campaign for Mayo Clinic

Mayo Clinic is a not-for-profit organization. Make a difference today.