It is an oil-based steroid containing four types of esters of testosterone. It is available only in injectable form. The drug is in activated form and starts acting as soon as it is injected. Itching at the injection sites is commonly seen due to its fast and continuous action. The main reason for its prolonged action is its ability to stay intact in the presence of body fluids. While other steroids tend to dissolve in the blood or serum, Sustanon will not change its chemical structure or reactive phase.