A method of delivering epinephrine includes placing a distal end surface of a medical injector into contact with a target location of a patient. The medical injector includes a housing, an energy storage member, and a medicament container containing a dose of epinephrine effective for administration to the patient experiencing anaphylaxis and having a weight of less than 15 kg. The medicament container is coupled to a needle. The medical injector is actuated such that the energy storage member produces a force to move the needle from a first needle position to a second needle position. A distal tip of the needle extends from the distal end surface by a distance of between 7 millimeters and 8 millimeters when the needle is in the second needle position. A portion of the force is exerted to expel the dose of epinephrine when the needle is in the second position.