What could potentially happen if an intramuscular vaccine is administered too high?

Administering an intramuscular vaccine too high in the deltoid muscle can lead to severe shoulder pain and injury. This occurs because when the injection is placed at an incorrect site, it may impinge on the axillary nerve or other anatomical structures in the shoulder area, leading to pain, nerve damage, or even conditions such as shoulder synovitis or bursitis. Proper technique is critical, as it ensures the vaccine is injected into the muscle while avoiding crucial nerves and blood vessels. Additionally, an injection placed too high could lead to vascular injury or inflammation of the shoulder joint, which can be quite painful and may result in limited mobility and further complications. Understanding the correct anatomical landmarks for intramuscular injections is essential to avoid these adverse outcomes.