Anabolics 101 – Andriol (Testosterone Undecanoate)

Andriol® is an oral testosterone preparation that contains testosterone undecanoate (in an oil base) in a soft gelatin capsule. This drug is very different than most oral anabolic steroids, which are usually c-17 alpha alkylated to survive first-pass metabolism through the liver. Instead, esterification and suspension in oil allows the testosterone undecanoate in Andriol® to be partially absorbed through the lymphatic system along with dietary fat. This bypasses the destructive first-pass through the liver, providing sustained physiological levels of testosterone to the body. The actual oral bioavailability of Andriol® is estimated in some studies to be approximately seven percent. In design, this steroid is essentially a non-toxic and orally active testosterone, intended to provide a unique alternative to testosterone injections and other hepatotoxic oral anabolic-androgenic steroids (AAS). In practice, this steroid is usually not regarded as a bodybuilding drug of significance, though is sometimes incorporated into stacks with other agents.

How Supplied

Oral testosterone undecanoate preparations are available in various human drug markets. The older formulations supply 40 milligrams of testosterone undecanoate in oleic acid, contained in small, soft gelatin capsules. Andriol® Testocaps™ supplies 40 milligrams of testosterone undecanoate in castor oil and propylene glycol monolaurate, contained in small, soft gelatin capsules. Subtracting the ester weight, each 40-milligram Andriol® capsule contains 25.3 milligrams of (base) testosterone.

Effective Dosages

For bodybuilding purposes, high doses would be required to reach strong supraphysiological levels of testosterone. This would generally call for a minimum dosage of 240-280 milligrams per day (6-8 capsules) for men, which are taken in cycles of six to eight weeks. A more common effective dosage, however, would fall in the range of 400-480 milligrams (10 to 12 capsules) per day. This drug is not recommended for women for physique or performance-enhancing purposes, due to its strong androgenic nature and tendency to produce virilizing side effects.

Note: Andriol® should always be taken with meals, preferably containing a moderate fat content (20 grams) to maximize lymphatic absorption. Low bioavailability has been noted when taken in the fasted state. The total daily dosage should be divided into a minimum of two applications, taken in the morning and evening, to maintain more consistent elevations of serum testosterone.

Side Effects

Estrogenic: Testosterone is readily aromatized in the body to estradiol (estrogen). Elevated estrogen levels can cause side effects such as increased water retention, body fat gain and gynecomastia. Anti-estrogens such as clomiphene citrate or tamoxifen citrate are commonly applied to prevent estrogenic side effects. One may alternately use an aromatase inhibitor like Arimidex® (anastrozole), which more efficiently controls estrogen by preventing its synthesis.

Androgenic: Testosterone is the primary male androgen, responsible for maintaining secondary male sexual characteristics. Taking oral testosterone undecanoate in doses exceeding normal therapeutic levels is likely to produce androgenic side effects including oily skin, acne and body/facial hair growth. Men with a genetic predisposition for hair loss (androgenetic alopecia) may notice accelerated male pattern balding. Women are warned of the potential virilizing effects of anabolic-androgenic steroids, especially with a strong androgen such as testosterone. These may include deepening of the voice, menstrual irregularities, changes in skin texture, facial hair growth and clitoral enlargement.

Liver Toxicity: Testosterone does not have hepatotoxic effects. Liver toxicity is unlikely.

Cardiovascular: Anabolic-androgenic steroids can have deleterious effects on serum cholesterol, increasing the risk of arteriosclerosis. They may also adversely affect blood pressure and triglycerides, reduce endothelial relaxation and support left ventricular hypertrophy, all potentially increasing the risk of cardiovascular disease and myocardial infarction. People with high cholesterol or a familial history of heart disease should be especially careful when considering AAS abuse. Note that therapeutic doses of oral testosterone undecanoate used to correct insufficient androgen production in otherwise healthy, aging men are unlikely to increase atherogenic risk, and may actually improve lipid profiles and cardiovascular risk factors.

Testosterone Suppression: All anabolic-androgenic steroids, when taken in doses sufficient to promote muscle gain, are expected to suppress endogenous testosterone production. Without the intervention of testosterone-stimulating substances, testosterone levels should return to normal within four months of drug cessation. Note that prolonged hypogonadism can develop secondary to steroid abuse, necessitating medical intervention.

The above side effects are not inclusive.



Oral testosterone undecanoate remains widely available around the world. It is produced almost exclusively by or under license from Organon (now Merck/MSD). Few preparations found on the black market are counterfeit, given the low demand and high cost of duplicating the unique softgel Andriol® capsules.