Hello, You suffer from numbness in the outer upper arm due to local anesthesia injection in the inner upper arm as local anesthesia causes numbing so that insertion or removal reduces pain. Local anesthesia is safe though sometimes, it may cause numbness in the arm, caused by an injury, compressed or pinched nerves, overuse of arm muscle. Nerve compression issues usually go away on their own or with physical therapy. You are suggested to take anti inflammatory medicine, one SOS when pain or discomfort to reduce any swelling or redness. You can take non-sedating antihistamine, one SOS when needed to reduce allergic reactions and discomfort. In case you are very uncomfortable or have severe numbing then you can talk to the concerned anesthetist so that he may give a sedative instead of anesthesia. Dehydration can trigger symptoms. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician