It can be difficult to know whether an allergic reaction has progressed to the point where it is necessary to use an auto-injector to treat the person. If they have a known history of allergies and allergic reactions and have come into contact with an allergen that has been known to cause this type of reaction in the past, this may be an indicator that an auto-injector is needed. If the person is having difficulty breathing and appears to be in severe respiratory distress, along with any other warning signs of an allergic reaction, such as throat closing, swelling of the tongue or lips and loss of consciousness, you should administer the epinephrine auto-injector immediately.