Answer – Earlier is Better
Treating anaphylaxis early is best for a good outcome. Epinephrine is the best medication for treating anaphylaxis. Epinephrine is a very safe medication. Your body makes epinephrine in response to stress. Therefore, your body is used to seeing this and breaking it down.
It is not like an antibiotic or other foreign drug. If you were to get frightened by a bear your body will release epinephrine. It is in and out of your body very quickly. If you or someone you know is having an allergic reaction it is like a door opens and histamine floods your system. If you take antihistamine it helps to block the histamine, but it does NOT shut the door so histamine will keep flooding your system. The longer and more histamine that gets into your system the harder it is to STOP a reaction. Therefore, it is lifesaving to give epinephrine quickly to shut the door and stop the reaction.
If you were to give epinephrine for a mild reaction it is safer than waiting to see if the reaction gets more severe because if you try to treat later with epinephrine it can be harder to stop the reaction. In the past it has been advised to go to the emergency department if epinephrine is given. This was advised to have the patient monitored for further symptoms, not because epinephrine is dangerous.
Epinephrine can seem scary to patients because it is a shot, however the medication itself is very safe and has been used for years to treat asthma, hives, and anaphylaxis!