Zyvec 4mg Injection belongs to a group of medicines called muscle relaxants. It is used along with general anesthesia or sedatives to provide skeletal muscle relaxation during surgical procedures. It is also used to facilitate emergency airway management in patients in intensive care. Zyvec 4mg Injection is administered by a healthcare professional. You should not self-administer this medicine at home. The dose and duration will depend on what you are taking it for and how well it helps your symptoms. The most common side effects of this medicine include injection site reactions such as pain, redness, and swelling. Long-term use of this medicine may cause skeletal muscle weakness or even paralysis. You should let your doctor know if the side effects bother you. Your doctor may be able to suggest ways of preventing or reducing the symptoms. Before using it, to make sure it is safe for you, you should let your doctor know if you have any other medical conditions or disorders. You should also tell your doctor all the other medicines you are using or taking. Pregnant and breastfeeding women should consult their doctors before using this medicine.