Major classes of shock include:

• cardiogenic shock (associated with heart problems)
• hypovolemic shock (caused by inadequate blood volume)
• anaphylactic shock (caused by allergic reaction)
• septic shock (associated with infections)
• neurogenic shock (caused by damage to the nervous system)

Shock can be caused by any condition that reduces blood flow, including:

• Heart problems (such as heart attack or heart failure)
• Low blood volume (as with heavy bleeding or dehydration)
• Changes in blood vessels (as with infection or severe allergic reactions)

Shock is often associated with heavy external or internal bleeding from a serious injury. Spinal injuries can also cause shock.

Toxic shock syndrome is an example of a type of shock from an infection.

A person in shock has extremely low blood pressure. Depending on the specific cause and type of shock, symptoms will include one or more of the following:

• Anxiety or agitation
• Confusion
• Pale, cool, clammy skin
• Low or no urine output
• Bluish lips and fingernails
• Dizziness, light-headedness, or faintness
• Profuse sweating, moist skin
• Rapid but weak pulse
• Shallow breathing
• Chest pain
• Unconsciousness

• Call 911 for immediate medical help.
• Check the person's airway, breathing, and circulation. If necessary, begin rescue breathing and CPR.
• Even if the person is able to breathe on his or her own, continue to check rate of breathing at least every 5 minutes until help arrives.
• If the person is conscious and DOES NOT have an injury to the head, leg, neck, or spine, place the person in the shock position. Lay the person on the back and elevate the legs about 12 inches. DO NOT elevate the head. If raising the legs will cause pain or potential harm, leave the person lying flat.
• Give appropriate first aid for any wounds, injuries, or illnesses.
• Keep the person warm and comfortable. Loosen tight clothing.

IF THE PERSON VOMITS OR DROOLS

• Turn the head to one side so he or she will not choke. Do this as long as there is NO suspicion of spinal injury.
• If a spinal injury is suspected, "log roll" him or her instead. Keep the person's head, neck and back in line and roll him or her as a unit.

• DO NOT give the person anything by mouth, including anything to eat or drink.
• DO NOT move the person with a known or suspected spinal injury.
• DO NOT wait for milder shock symptoms to worsen before calling for emergency medical help.

Call 911 any time a person has symptoms of shock. Stay with the person and follow the First Aid steps until medical help arrives.

Learn ways to prevent heart disease, falls, injuries, dehydration, and other causes of shock. If you have a known allergy (for example, to insect bites or stings), carry an epinephrine pen. Your doctor will teach you how and when to use it.

Once someone is already in shock, the sooner shock is treated, the less damage there may be to the person's vital organs (like the kidney, liver, and brain). Early first aid and emergency medical help can save a life.