2) Hitting the lymphatic system.
Hitting the lymphatic system is very rare. The lymphatic system is as vast as the circulatory system but the standard injection sights (Glute, ventro-glute, medial delts and vastus lateralis) are generally void of lymphatic nodes. If a lymph node is hit with an injection pain is likely to be severe and edema vast. The swelling will come on very fast and be extensive. It is also likely to along the lymph system to the next lymph gland. This is most noticeable with a vastus lateralis shot where the swelling tracks down toward the back of the knee. Unlike the edema experienced with tissue irritation (within the muscle only) the edema with a lymphatic puncture will be both inter and intra-muscular with a moderate amount of swelling just underneath the skin giving it a softer puffy feel. This can be tested for by pressing the swollen area with your finger, if in indent remains you have a more systematic edema and more than just local tissue irreation. The other most noticeable difference is that the swelling should not be warm/hot to touch.
Ice and ibuprofen may help. The affected area must be rested and the patient can expect pain and swelling to start to dis after 72 hours and last at least 10 days. The painful area must not be massaged.
