What are the things to do in an emergency?

Chest pain, choking, bleeding, fainting, seizures. If an emergency occurs, how would you react? Do you know the first steps of first aid?

"People are often hesitant to get involved in an emergency situation," William Walters, MD, an emergency medicine specialist at Temple University School of Medicine in Philadelphia, tells WebMD. "It's not so much they don't want to help. They're worried they won't know what to do."

After all, emergencies can happen anywhere -- at a game, on a city street, at the grocery store, at home. What should you do?

Call 911. Better safe than be sorry, says Walters. "It's better that 911 get too many calls than too few," he says. "We routinely hear from paramedics summoned to a residence, for what neighbors thought was an emergency, to find out everyone's fine. There are never hard feelings about that. Paramedics expect that as part of the job. We'd much rather show up and find the person in good health at home than be called too late and things have spiraled out of control."

Stay calm. We've all heard stories about the Good Samaritan who gets hit by a car while trying to help someone else. "Creating another accident or another victim complicates things much more -- almost more than not getting involved. If you can't help safely, you shouldn't help," Walters tells WebMD. "It's important that you stay calm, make sure you're not putting yourself or anyone else in jeopardy, then attempt to help."

Start CPR. "Even people who have never taken a CPR course can be directed by a dispatcher to do CPR," says Walters. "Many 911 dispatchers are trained to teach CPR over the phone. You can do chest compressions without even doing mouth-to-mouth. ... It's better than doing nothing."

Imagine these common situations. Here's what to do:

Emergency: Dizziness, Fainting. You're sitting at a game, maybe in the airport. A guy says he doesn't feel well. "If he tells you -- a perfect stranger -- that he feels weak, ill, or dizzy, you should be dialing 911," says Walters. "He needs medical attention." There are many medical causes for these symptoms, like a heart condition, diabetes, low blood sugar, pregnancy, heart attack, or it could be heat-related.

While you wait for paramedics to arrive:

Check alertness: Ask, "Are you OK?" advises Elda Ramirez, RN, MSN, FNP, CEN, professor and division head of emergency care at The University of Texas School of Nursing at Houston. "If they respond, ask 'Do you know where you are?' Ask things to determine level of orientation. If they become unresponsive, check for pulse, check to see if they're breathing. If you're by yourself, you have to find someone to help you."

Check breathing: Listen for breathing through the nose, watch the chest for rise and fall. Take a pulse, either at the wrist or neck. If they are breathing and have a pulse, you should stay with them to offer support. Again, 911 can help you figure out how to take someone's pulse.

Start CPR: If the patient isn't breathing and does not have a pulse, start CPR.

Make the patient comfortable: "If this person has been out in the heat, move them to a shady spot. If they're sweating, pour water over their skin," Ramirez tells WebMD. Elderly people or very young children are more prone to heat-related conditions. "If they're awake, give them fluids to drink," she says.

Emergency: Chest Pain. If someone grabs their chest and says "my chest hurts," assume it's a heart attack. "Chest pain is a heart attack until proven otherwise," Ramirez tells WebMD. "That's how we look at it in the ER world. A 17-year-old can have a heart attack. Anyone can have a heart attack."

Plan of action: Dial 911. Then check airway, breathing, circulation (ABC). Are they breathing? Do they have a pulse? If not, start CPR.

"The sad thing is, people get scared if they don't know CPR, they don't want to do the wrong thing," says Ramirez. "The most important thing -- if someone is not breathing -- is to position their head with the chin up, get their tongue out of the way (so the airway is open), then start doing chest compressions."

Learn more about how to handle a heart emergency, including information about AEDs, in this article from The Cleveland Clinic.

Emergency: Choking. You're talking at the dinner table, and someone starts coughing. When does it become an emergency? "When they're coughing, it's OK, because there is air movement, they are breathing," Ramirez says. "If they're not making any noise whatsoever, their face is getting red, you need to do the Heimlich maneuver. At that point, they are not breathing."

Caution: "If they're coughing, doing the Heimlich can make it worse," she adds. Also, hitting a choking person on the back can make the situation worse -- the food may go back into the windpipe. "They need to work it out themselves; leave them alone, until they reach a point where there's no airway noise."

Take time now to re-read directions on the Heimlich maneuver, she suggests.

Emergency: Bleeding. "When someone cuts their finger, they think they're going to bleed to death," says Ramirez. "People don't understand that there are nine units of blood in the body. The parts of the body that bleed a lot are the scalp, fingers, and toes. A nosebleed can bleed a lot. A cut in the vaginal area can bleed a lot. But they won't bleed to death."

Nosebleeds can have a serious cause, like high blood pressure, or they can be caused by chronic nose-picking. "If someone with high blood pressure has a serious nosebleed, you're looking at potential disaster," Ramirez tells WebMD.

Rule of thumb: "When something scares you, call 911 or go to the hospital," she says. "We can say whether it's an emergency or not."

A cut tendon may be more problematic than the bleeding, she says. "It may need to be closed with sutures, or they may never be able to use that finger again. We hear it all the time, men who say, 'I'm fine, I'm fine.' They need to have that cut looked at."

Don't make a tourniquet: "We don't use tourniquets anymore," says Ramirez. "They cause too much damage to tissues. We advise putting direct pressure on the site. Even if it's a partial amputation, put a rag around it, hold it tight."

Here's more information on how to stop bleeding in the face or mouth.

Emergency: Seizure. The symptoms of seizures vary. The person may fall down and/or make erratic movements. Or their head might jerk and eyes flutter. This can happen to children who have a high fever, to someone with epilepsy, or when someone is having a stroke.

Any seizure warrants medical attention. Call 911. While waiting for paramedics, make sure the person does not hurt themselves. "If they fall down, get everyone away from them," says Ramirez. "Don't get near them; they could hurt you. Don't try to put something in the person's mouth (as used to be advised); it's too dangerous. Also, watch the clock -- how long the seizure lasts."

Read about first aid for seizures: how to protect yourself and others.