Boldenone Undecylenate is commonly known as Equipoise. The drug is synthetic with a structure similar to testosterone. The only difference is that boldenone has a double bond. It has a half-life of 14 days. It has strong anabolic properties and low androgenic potency. Like other steroids, it binds to the androgen receptor and controls the expression of androgen genes.
Equipoise is an injectable and is mainly used in veterinary medicine, particularly for horses. The FDA has not approved Equipoise for human use; instead classified it as a controlled substance. However, bodybuilders and athletes use it illegally to increase muscle mass and improve performance. They use it by stacking and keeping testosterone as a ‘base.’ 
Like testosterone, Equipoise helps increase muscle mass. However, if misused, it can have adverse side effects such as acne, oily skin and facial hair growth. Additionally, it can significantly increase red blood cell production.
Furthermore, boldenone is metabolized to estrogen in the body. Increased estrogen levels can cause gynecomastia and increased water retention. Estrogen side effects are produced when doses are significantly high. 
According to studies, Equipoise can cause cardiovascular problems. Also, heart injuries are pretty standard. Though, boldenone is less potent compared to other synthetic oral steroids. Studies of adverse effects in rats showed a significant increase in relative heart weight.
Additionally, long term use can cause weight gain . However, the effect of Equipoise on the liver is less drastic. Since Equipoise is not c-17 alpha alkylated, there are no hepatotoxic effects, and liver damage is less likely.