Will Finasteride Make You Fail a Drug Test? Understanding the Nuances

October 11, 2025 •

4 min read

From 2005 to 2009, the World Anti-Doping Agency (WADA) banned finasteride because it was used as a masking agent to conceal the use of anabolic steroids during doping tests. When asking, Will finasteride make you fail a drug test?, the answer depends heavily on the type of test you are taking and the context in which it is administered.

Quick Summary

Finasteride will not cause a typical workplace drug test failure, as it is not a controlled substance. In competitive sports, however, its historical use as a masking agent for anabolic steroids required robust testing protocols. Modern doping tests can now detect finasteride directly.

Key Points

Standard Drug Tests: Finasteride will not cause you to fail a typical workplace drug test, as it is not a controlled substance and is not screened for.
Sports Doping History: Finasteride was formerly banned by the World Anti-Doping Agency (WADA) because it could mask the use of performance-enhancing steroids.
Masking Mechanism: By inhibiting 5-alpha reductase, finasteride alters the body's steroid profile, historically making it harder to detect anabolic steroid abuse in athletes.
Modern Detection: Advanced testing methods can now directly detect finasteride and its metabolites, leading to its removal from WADA's banned substance list in 2009.
PSA Test Interference: Finasteride can lower prostate-specific antigen (PSA) levels, affecting prostate cancer screening results, but this is a separate issue from drug abuse testing.
Transparency is Key: Always inform your healthcare provider and any lab personnel performing a test that you are taking finasteride to avoid misinterpretation of results, especially for medical tests like PSA screening.

Finasteride and the Drug Test: The Critical Distinction

For the vast majority of people subject to a standard workplace drug screening, taking finasteride will not result in a positive test result. These tests typically screen for common illicit substances, such as cocaine, marijuana (THC), opiates, and amphetamines, and do not look for prescription medications unless specifically requested. Finasteride is not a controlled substance and is therefore not the target of these standard screenings.

However, the situation is different for competitive athletes under the jurisdiction of anti-doping organizations like the World Anti-Doping Agency (WADA). In the context of sports, finasteride's interaction with the body's metabolic processes is a serious concern, which led to its ban in competitive sports for a period of time.

Finasteride as a Doping Masking Agent

Finasteride functions by inhibiting the enzyme 5-alpha reductase, which is responsible for converting testosterone into dihydrotestosterone (DHT). In a sporting context, finasteride was abused by athletes using anabolic steroids to mask their steroid use. By altering the body's natural steroid profile, finasteride could interfere with doping control tests. Investigations in the mid-2000s demonstrated how this mechanism worked.

Altered Steroid Profiles: By inhibiting 5-alpha reductase, finasteride reduces the excretion of 5-alpha steroids like androsterone in urine. This causes significant shifts in the ratios of various steroids, which are normally stable parameters monitored during doping control.
Suppressed Norandrosterone Excretion: Finasteride was particularly effective at masking the use of 19-norsteroids, a class of anabolic steroids. It could suppress the excretion of norandrosterone, a key metabolite of these steroids, by up to 84%. Since doping tests rely on detecting norandrosterone above a certain threshold, this manipulation could lead to a false-negative result for steroid abuse.

The End of Finasteride as a Masking Agent

Due to its effectiveness as a masking agent, WADA placed finasteride on its prohibited list in 2005. This ban led to suspensions for several high-profile athletes who were taking the medication for legitimate purposes, such as hair loss. However, advancements in drug testing technology eventually made the ban unnecessary. Starting in 2009, WADA removed finasteride from its prohibited list after modern testing methods, specifically liquid chromatography-tandem mass spectrometry (LC-MS/MS), became sophisticated enough to detect finasteride and its metabolites directly.

These improved testing procedures allow laboratories to identify the presence of finasteride in an athlete's urine sample. This means that while finasteride could still be used to alter an athlete's steroid profile, its presence would now be flagged and investigated immediately by anti-doping authorities.

Athlete Cases Involving Finasteride

Before the WADA ban was lifted, several athletes faced suspensions after testing positive for finasteride, despite often claiming the medication was for treating male pattern baldness. Notable examples include:

Zach Lund: A U.S. skeleton racer who was banned from the 2006 Winter Olympics after testing positive.
José Théodore: A Canadian professional ice hockey goaltender who failed a pre-Olympic screening in 2006.
Romário: A Brazilian football player who received a four-month suspension in 2007.

The PSA Test: A Different Kind of Interaction

It is important to differentiate between drug tests for illicit substances and other types of medical tests. Finasteride does affect the results of Prostate-Specific Antigen (PSA) tests, which are used to screen for prostate cancer. The medication can lower a person's PSA levels, which is why patients are advised to inform their doctor that they are taking finasteride before a PSA test is performed. This interaction has nothing to do with drug abuse but is a crucial piece of information for medical professionals interpreting a patient's results.

Comparison: Standard vs. Sports Doping Drug Tests


Feature	Standard Employment Drug Test	Sports Doping Control Test
Purpose	To detect illicit drug use for safety and policy compliance.	To detect performance-enhancing drugs and methods, ensuring fair play.
Finasteride Detection	Not tested for; not a controlled substance.	Actively monitored and detected using advanced methods (e.g., LC-MS/MS).
Masking Potential	None.	Historically significant, but now detectable and flagged.
False Positive Concern	Minimal concern with modern confirmatory testing.	Highly relevant historically, led to ban; now mitigated by advanced detection.
Consequences	Employment termination, disciplinary action.	Disqualification, suspension from competition, fines.

Conclusion

For the average person concerned about a workplace drug test, finasteride will not make you fail a drug test. The medication is not a controlled substance and is not screened for during standard employment screenings. The only context in which finasteride is a drug-testing concern is competitive sports, where it was historically banned as a masking agent for anabolic steroids. However, even in this domain, modern detection methods can now identify finasteride directly, rendering it ineffective as a masking agent and removing it from the prohibited list. Always inform healthcare providers and lab personnel about any medications you are taking before any medical or laboratory test.

For more information on the investigations that led to finasteride's initial inclusion on the WADA prohibited list, consult the studies conducted by institutions like the German Sport University Cologne, supported by WADA.

Frequently Asked Questions

No, it is highly unlikely that finasteride would cause a false positive on a standard drug test. These tests screen for specific classes of illicit drugs, and finasteride is not in any of these categories. Any initial false positive from a less specific immunoassay would be cleared up by confirmatory testing, which is standard procedure.

WADA banned finasteride from 2005 to 2009 because it was used as a masking agent for anabolic steroids. It inhibits the enzyme 5-alpha reductase, which can alter the steroid profile in an athlete's urine and make it difficult to detect steroid use.

No, finasteride was removed from WADA's banned substance list in 2009. This was because testing technology had advanced enough to allow for the direct detection of finasteride, rendering its masking properties ineffective.

For a standard workplace drug test, it is generally not necessary, as finasteride is not a controlled substance and is not screened for. However, it's always prudent to inform a medical professional about all medications you are taking before any medical lab test.

A standard drug test looks for common illicit drugs and does not screen for finasteride. A sports doping control test, however, specifically monitors steroid profiles and can directly detect finasteride due to its historical use as a masking agent.

Yes, finasteride is known to significantly affect Prostate-Specific Antigen (PSA) tests, which are used for prostate cancer screening, by lowering PSA levels. It is crucial to inform your doctor about your finasteride use before getting a PSA test.

Modern anti-doping laboratories use advanced techniques, such as liquid chromatography-tandem mass spectrometry (LC-MS/MS), to specifically identify and measure finasteride and its metabolites (like carboxy-finasteride) in urine samples.