EXPLAINER: Clomiphene, the drug behind Conor Benn’s failed VADA test

What is clomiphene, the drug Conor Benn tested positive for, and what does it do? An expert helps us understand the medical facts.

Earlier this week, the controversial, highly anticipated Son vs Son showdown between Chris Eubank Jr and Conor Benn collapsed in a very public way.

On Wednesday, the day of Benn and Eubank’s media workout, news broke that Benn had failed a Voluntary Anti-Doping Agency (VADA) test due to a positive result for clomiphene, a drug occasionally spelled as “clomifene,” and commonly known by the brand name “Clomid.” A cloud of awkwardness hung over the day, as fighters and promoters made cautious statements acknowledging the British Boxing Board of Control’s prohibition of the fight, while still expressing hope that an appeal would allow things to proceed as scheduled.

Within 24 hours, the show was officially canceled, though Matchroom promoter Eddie Hearn specifically only referred to the Eubank-Benn matchup as “postponed.”

We can’t say for sure whether Benn and Eubank will ever face each other in the ring. But, we can help answer some questions about clomiphene, the drug behind Benn’s failed VADA test. And the man to help us do it is Dr. Kevin Chu, a Men’s Health and Male Fertility Specialist in the Los Angeles area.

Dr. Chu has no medical relationship with Conor Benn, and has no involvement with the drug testing involved in this canceled fight, but he has published and presented extensive work in the field of urology and reproductive endocrinology and infertility, including research on the applications and use of clomiphene by men.

He spoke with Bad Left Hook about the history and purpose of clomiphene, how it’s taken and how long it lasts in the system, how it impacts testosterone, and how some bodybuilders have used it in the past. Dr. Chu also gave an example of an NFL player suspended after testing positive for clomiphene, and shared his personal experiences on how a healthy podcast co-host relationship should work.

Our conversation, lightly edited for length and clarity, follows.

BAD LEFT HOOK: Before we start talking about clomiphene as a drug, I want to get a little info about your expertise. We’re talking today because one of your co-authors on a paper that covered certain medical applications for clomiphene in men told me you were the person I should talk to for this story.

So, briefly, and with the humility that all highly skilled doctors are known for, can you tell us a little about your background on this topic and what led you to research work on clomiphene?

DR. KEVIN CHU: [Laughs] Absolutely. And I’m glad that recommendation came from my fantastic mentor, Dr. Ranjith Ramasamy.

Basically, I’m a fellowship trained Urologist. We cover things like men’s health and urological cancer. And, one of the areas I specialized in and spent some extra time in - did a lot of research and specialized microsurgical training on - is male infertility.

When it comes to the ability to conceive, it takes two to tango. Both the female and the male. And for the longest time, females were thought to be the main reason why couples were unable to conceive. But, in recent years there is a push to get males evaluated earlier, and we’ve taken a closer look at the male side. A lot of it is tied into how much testosterone and sperm production your body has.

So, in short, I’ve done a lot of research in the male fertility area, and I have a pretty strong understanding of the medications we can use to help men optimize their chances for conception.

Well, what is clomiphene? How long has it been around, what is its primary purpose, and how did that usage start or evolve over time?

Clomiphene came out in the 1960s. The main reason it was authorized for use was to induce ovulation in females that were having issues — for women who were inconsistently or unable to ovulate. This medication would increase hormone levels to induce that ovulation.

Later on in the 1970s, it was evaluated for men to observe if certain male hormones necessary for optimal reproductive and sexual health could be increased. And it was seen that it can increase testosterone and help with sperm production in patients that need it.

Because it’s largely been reported as a “female fertility drug,” let’s just address it again directly: It isn’t necessarily unusual for a male patient to use clomiphene for a medically valid purpose, correct?

Absolutely. I prescribe Clomid when a male patient is having infertility problems and corresponding tests show low sperm count and less than optimal testosterone. This is definitely one of the medications I go to to address both issues.

I should clarify that use in males is an off-label use. For females, it’s FDA-approved.

You mentioned Clomid specifically, which people may be more familiar with today as fertility treatments are more common than they were even just 10 or 15 years ago.

But for anyone unfamiliar with the drug– What are the options for taking clomiphene? Is it injected, ingested orally, or both? How does someone take it?

Clomid is only available in oral form, a pill. On the male side, we generally have patients take it three times weekly, or every other day. There is no injected form.

There are different isomer forms, one of them being enclomiphene citrate. I won’t get into too much detail, but it was a formulation that was looked at for a while with similar mechanisms of action. But again, it’s all taken orally.

In a previous explainer with a Toxicologist, he talked about how different methods of ingestion and usage can impact how long certain drugs remain effective, and how long they linger in the body.

For clomiphene, being taken orally, how long does it normally stick around in someone’s system?

The half-life of Clomid is five to six days, but it has reportedly been detectable in feces for up to six weeks. However, the main test used for detection is the urine test. A paper in the Journal of Clinical Endocrinology and Metabolism showed it may be in urine up to four months after use. Different patients had different detectable levels in their urine at varying time frames. So, in short, there isn’t a clear answer on that.

How tightly controlled is clomiphene? When I’ve done similar explainers in the past, there have been occasions where an incidental contact isn’t out of the question. There have also been others where it seemed very unlikely the substance behind the failed test would be ingested without intent.

Whether someone is trying to use it illicitly or for a medically prescribed purpose, how strictly controlled is clomiphene?

Clomiphene citrate is fairly controlled in terms of a physician needing to write you a prescription for you to get the medication. It’s not over the counter. On the other hand, it is not on the FDA Controlled Substances schedule. The World Anti-Doping Agency has it on its prohibited list.

I don’t mean to imply every explanation is an excuse after the fact, but whenever an athlete fails a drug test, we do hear a lot of the same things come up to suggest unintentional exposures. We hear about food additives, tainted supplements, mistakes with things connected to therapeutic use exemptions, those sorts of things.

So, I’m wondering if, based on your knowledge of clomiphene, there are past examples or logical reasons that could offer a potentially innocent explanation for a failed drug test?

It’s a bit outside my scope to postulate on unintentional exposures. I mostly deal with patients that have come to me with low testosterone symptoms or male infertility issues. That’s the reason I prescribe them Clomid.

Can we talk in general, not necessarily for Benn specifically, about how clomiphene might function as a performance enhancer? Why might someone choose this particular drug as a testosterone booster, and what specific benefit might it give a combat sports athlete?

Just talking about testosterone in general, there are two ways to increase it. And to be clear, as a doctor, I only treat men that have clinical indications to increase testosterone.

But in general, there are injections of testosterone that have been shown to raise your serum testosterone much higher. The issue with that, specifically in relation to my area of expertise, male infertility, is that when you give that testosterone directly, it tells your body’s natural pathway of producing testosterone to shut down. Because if your body senses you have enough testosterone, it’s not going to make more itself.

As a result, you can have side effects. For me, we see patients where sperm production gets completely shut down, so they have no sperm in their ejaculate, and essentially they are unable to conceive. Additionally, you can get atrophy of the testicles, because the testicles no longer need to make sperm or testosterone. As a result, they start shrinking.

Clomiphene tells your body to make more testosterone. It doesn’t deliver it wholesale. It’s not giving the final product; it instructs the body to increase testosterone. So, it’s been shown that bodybuilders can and do utilize Clomid as part of their workout supplementation. They can use it as part of their cycling routine. They’ll do testosterone injectables for a few months, and they’ll come off of it and take Clomid to instruct their body to start making normal testosterone again.

Is there any intermediate or long term health impact that use of clomiphene might have on a person that uses it for an extended period of time?

There wasn’t much research on long term effects until 2019, when a group from multiple institutions studied Clomid usage for more than three years, and did not see any significant adverse effects. Their results were published in the Journal of Urology.

Still, just in case anyone’s wife or girlfriend is on fertility treatments and they’re reading about testosterone boosting here, we probably want to discourage them from raiding her medicines for illicit use, right?

Um, yes. [Laughs] I am a doctor, and I am obviously a big proponent of consulting with a doctor before anyone starts taking these medications.

Anything related to this topic and this particular drug that we ought to consider?

Once we scheduled this conversation, I actually did a little research into athletes in the past who tested positive for Clomid. And I came across the story of an NFL player [NOTE: Indianapolis Colts linebacker Robert Mathis] who was suspended back in 2014 over a positive test for clomiphene. In one of the articles I read about it, he said something about how whenever he looked at his newborn kid, he had no regrets for what happened.

I can’t speak to the specific background for him or any other professional athletes, but as a male fertility specialist, your reproductive years are generally from 20 to 45. And, that is when a lot of professional athletes are in the prime of their careers.

So this is a drug that does increase testosterone, but in our field, speaking strictly as a male fertility specialist, we use it to try and help people conceive. Sometimes the whole story isn’t known, but from my understanding, these medication uses are to be disclosed to professional sport competition oversight committees as therapeutic-use exemptions.

Photo by Yui Mok/PA Images via Getty Images

It seems like it would have been mentioned already if Benn were taking this drug under medical supervision for fertility reasons, because it is such an obvious and sympathetic explanation for why it could have wound up in his test sample.

But I will mention that Benn is 26 years old, he’s been married to his wife Victoria for four years, and they have a one and a half year old son. So while it strikes me as an odd omission not to explain the result immediately, it’s not impossible that this might be a result of them actively trying to conceive another child.

I don’t want to speculate or postulate on this specific situation. As a male fertility specialist, I’ve treated a lot of men between the ages of 20 and 45. And we recommend to many patients that they take [clomiphene] to assist them in trying to conceive when their workup suggests the medication may help.

Before we go, I want to mention that you just finished up your first 32 episode season of the Man Up Podcast. Any particular episode you’d recommend for people reading this that might want to check it out?

Absolutely. In Episode 7, we actually have a great chat with Dr. Ramasamy, and that episode is all about positives and negatives about steroids. So, clomiphene gets touched upon there. For guys wondering what the negative fertility effects of taking steroids can be, or what the concerns are, or what options there are - we go over it in that episode.

I’ll also point out that unlike my editor and I, who only do an audio podcast, and won’t even record in rooms that have mirrors or highly reflective surfaces… You guys are young, healthy, attractive-looking doctor types. You guys put your episodes out on YouTube and elsewhere as a video program as well.

Yeah! We see all sorts of different patients, and we wanted to get it out in any sort of medium that could get the information to every man on the planet. Interestingly enough, in our market research, we found more women get content from Instagram. But, males, and particularly young males, go to YouTube with their questions to try and find answers.

Out of curiosity, one podcaster to another: How often does your co-host bring up Bridgerweight as a way of trolling you and derailing the show?

Umm, I can’t say it’s ever happened. [Laughs]

Is that something that happens for you?

More than I’d like, Dr. Chu. Much more than I’d like. But it’s good to know that doesn’t happen to everybody.