You don't have to be a doctor to help someone in distress. Sometimes little acts of bravery is all it takes.
Heimlich Maneuver is a simple life-saving technique to help someone who is choking due to obstructed airways. To perform Heimlich maneuver, stand up behind the person, grab him by the belly button, and pull your hands back, applying a an upwards force. Created pressure will expel the foreign object from your lungs.
There is a small risk of gastric rupture that may occur if the pressure is too high, but even then, the benefit of saving someone's life outweighs the risks.
Epipen, otherwise known as Epinephrine auto injector, is a medical device that auto inject medicine into your body, typically the thigh. To use the epipen: stab it to the thigh and keep for ten seconds.
There are two main reasons why people might die from anaphylaxis. Suffocation is primary cause, where stop breathing because your airways are too swollen. Second is shock, where your blood vessels dilate, blood pressure drops and you go into hypotension, putting you in a cardiopulmonary arrest.
During anaphylaxis the immune system produces biochemical product that makes airways swollen and make fluid leaks from your blood vessel to your lungs. Epinephrine constricts the vessels, reduces swelling, and increase the blood pressure, causing the bronchi to dilate so you can breath again. Epinephrine is considered the major life-saving medicine for anaphylaxis.
The thigh is a big muscle with a great blood supply. Once the medicine is injected, it is able to enter the bloodstream and circulate fairly quickly.
First things first, call 911. If there is someone else there with you, assign them the task of calling 911 and establish "scene safety." You have to make sure that you, or anyone else, don't get injured while helping the subject. Then, as a non healthcare provider, approaching them and verify if they are conscious. Ask a few simple questions: are you ok, what's your name ..etc. If they are unresponsive, start chest compression (CPR) until medical help arrives.
Make sure they are safe. Put them in a position where they will not choke or hurt themselves. Roll them a little bit on the side so that any vomit would go outside and not into the the airway. Do not put anything into their mouth, like they do it in the movies. That is actually dangerous. Call for help and let them be.