Oral Testosterone

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Testosterone Undecanoate: Oral Testosterone

Oral preparations of testosterone come in a pill form and are ingested. However, there is currently no oral testosterone form approved by the FDA for use in the United States. Therefore, orally available testosterone has no place in testosterone replacement therapy in the US.  Most oral forms available on the underground market may cause significant liver damage and should be avoided. The reason that this form of testosterone may damage the liver is that it must be modified, so that it can pass through the liver when it is orally ingested.



Oral Testosterone Overview

The liver readily deactivates oral testosterone. In order to survive its first pass through the liver, the testosterone molecule must be altered. Specifically, a methyl group is installed at the 17th carbon (C-17) position on the testosterone molecule. While methylating the C-17 alpha position makes the molecule able to survive the first pass through the liver, it also causes significant liver toxicity. In addition, this modified form also acts negatively on the lipid profile (lowering of HDL cholesterol).1,2

The only safe form of oral testosterone is testosterone undecanoate.  However, testosterone undecanoate is only available for use outside of the United States. It is marketed under several brand names including Andriol, Undestor, and Nebido among others. (Testosterone undecanoate escapes liver metabolism by being delivered in an oily vehicle that is first absorbed by the lymphatic system. Therefore, it does not need to pass through the liver.) For men outside of the the United States, it is relatively safe and convenient to dose. Long-term use has been proven to be safe, as demonstrated in a 10-year study.3 Unfortunately, it still does have the potential for liver toxicity. It also has a short half-life. As a result, it must be taken up to four times per day and can cause fluctuations in testosterone levels throughout the day.4-6

In January 2014, Clarus Therapeutics submitted a new drug application to the US Food and Drug Administration (FDA) for the first orally available testosterone formulation. In September 2014, a US FDA advisory committee voted against the approval of Clarus Therapeutics’ testosterone undecanoate (TU) gel capsules as a testosterone replacement therapy (TRT) option.


Pros of Orally Available Testosterone:

  • Easy to take and to dose. Unfortunately, no forms are FDA approved in the United States. Outside of the US, testosterone undecanoate is the only safe form to use because it does not damage the liver like other oral forms.

Cons of Orally Available Testosterone:

  • May cause liver damage
  • Must take multiple times per day
  • Fluctuations in testosterone levels
  • No FDA approved oral testosterone available in the United States.


None: There is no FDA approved oral testosterone in the United States.


Better Testosterone Replacement Therapy Options

Testosterone Administration Available-1

In the US, oral agents have no place in testosterone replacement therapy in men. (Note: Oral testosterone that is physically swallowed differs from oral testosterone lozenges, which are not swallowed but absorbed through the gums.) Better, more common treatment options come in the form of injections, transdermal gels, nasal gels, and pellets.

Testosterone injections have been around for many decades. The two most common injectable forms (testosterone cypionate and enanthate) are both generic medications in the United States. Injectable forms are very inexpensive if self-administered.  As opposed to injectable forms, the testosterone gels are relatively new. Most forms come under a brand name. As such, they are more expensive. Brand names include Androgel, Axiron, Bio-T-Gel, Fortesta, and Testim. Lastly, pellets, which are implanted under the skin by a physician, offer another viable TRT option.


External Resources: Medscape: Types of Testosterone

Updated: April 30, 2015


1. Bagatell, C.J., & Bremner, W.J. (1995). Androgen and progestagen effects on plasma lipids. Progress in Cardiovascular Diseases, 38(3), 255-271.

2. Yoshida, E.M., Erb, S.R., Scudamore, C.H., & Owen, D.H. (1994) Severe cholestasis and jaundice secondary to an esterified testosterone, a non-C17 alkylated anabolic steroid. Journal of Clinical Gastro enterology, 18(3), 268-270.

3. Gooren, LJ. A ten-year safety study of the oral androgen testosterone undecanoate. J Androl. 1994; 15; 212-215.

4. Dandona P, Rosenberg MT. A practical guide to male hypogonadism in the primary care setting. Int J Clin Pract. May 2010; 64 (6): 682-696.

5. Bhasin S, Basaria S. Diagnosis and treatment of hypogonadism in men. Best Pract Res Clin Endocrinol Metab. Apr 2011; 25 (2): 251-270.

6. Miner MM. Low Testosterone Medscape CME Expert Column Series. Issue 3: Delivering Safe and Effective TRT. Medscape Education. 2011.