Equirab 1500 Injection is derived from the blood of horses. It neutralizes the virus at the wound site within a few hours. There are two types of Rabies Immunoglobulin (RIG), human (hRIG) and equine (eRIG). Both have similar clinical effectiveness in eliminating the virus at the wound site. Equirab 1500 Injection is given as an injection by a doctor or nurse. It is indicated in individuals with category III exposures (in-depth injury). RIG neutralizes the rabies virus at the inoculation site before the immune system responds to the vaccine by the production of rabies virus-neutralizing antibodies. Both active (vaccine) and passive immunization (Immunoglobulin) prevent the rabies virus from infiltrating the central nervous system, but become ineffective once the virus has crossed into the central nervous system. Equirab 1500 Injection is administered only once in a lifetime.The most common side effects include nausea, rash, and stomach upset. They do not normally last very long. Sitting or lying down can sometimes help. Consult your doctor if any of the side effects persist or worry you.Before having the injection, you should tell your doctor if you have ever had an allergic reaction to an immunoglobulin. Some other medicines may react with the equine rabies immunoglobulin so talk to your doctor about other medications you are taking as well. You should consult your doctor first if you are pregnant or breastfeeding.