Biceps abscess drainage Synthol is not a steroid and not even a drug. Basically, the synthol is an oil that is composed mainly of fatty acids and to a lesser extent of benzyl alcohol and lidocaine. This acid was developed by Chris Clark in the 80s with the intention that bodybuilders could fix their muscular defects in search of perfect symmetry. It is mainly used in the arms, when they refuse to grow, and in the twins. Synthol allows the muscle to expand and, consequently, increases its volume.