Omnadren is an oil-based injectable containing a blend of four different testosterone esters: testosterone propionate, phenylpropionate, isocaproate and caproate.

Omnadren has strong androgenic side effects, which are pronounced with Omnadren, as with all testosterones. Oily skin, acne, increased body/facial hair, and depending on the individual an increase in aggressiveness can occur. Omnadren can also be hard on the hairline. This is partly due to the conversion of the testosterone into dihydrotestosterone (DHT). Test is converted to DHT via the 5-alpha reductase enzyme. While DHT is more potent than test at the androgen receptor (the double bond is removed from the carbon4-carbon5 bond and replaced with a hydrogen atom on each) and is responsible for some growth.

It can also cause some negative side effects as well. Testosterone, because of this bond is actually much more anabolic, in practical terms, because it. For example: DHT formation in the scalp is suspected of causing/expediting male pattern baldness. To possibly combat this, one can use finasteride (Proscar). This drug will inhibit the conversion of testosterone to DHT but many users will report that since DHT is more potent at the androgen receptor than test, gains in muscle mass as well as strength will diminish. On the other hand, a lack of DHT caused by blocking 5-AR can sometimes cause gynocomastia.