Back when I was younger (~21 years old), I was a regular pot smoker.

Not the kind of stoner that would wake and bake, smoke throughout the day, etc.

But every night I would burn a small bowl or roll a real small joint and smoke about half of it.

For various reasons, I decided to quit around the age of 24, and up until this point barely even thought about the stuff.

Fast forward 15 years, and I recently started to dabble in the occasional joint or 2.

I’ve been doing this for the last few months, and have been noticing a trend.

A disturbing one…

Lately, I’ve noticing my libido and sex drive have been gradually deteriorating at a rapid rate.

Before, I would wake up first thing in the AM, every AM, with a pretty rigid boner.

Now, my morning woods have virtually disappeared.

I also noticed I barely think of sex anymore, and random boners throughout the day have simply stopped.

I’m even feeling the other typical symptoms of decreased testosterone, including a lack of energy, mood swings, difficulty concentrating, and even a decrease in sports performance.

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What could be wrong?  Am I just getting older?

I haven’t changed my diet, I still exercise / lift heavy nearly every single day, and don’t take any medications.

The one (and as far as I can tell, ONLY) difference was taking weed back up again.

So it got me thinking…

I know a reduction in testosterone levels can be cause for libido issues, but was marijuana actually lowering it?

I decided to take the scientific route, and got my blood tested just a couple of weeks ago just to see where my numbers were at.

Part of that test included a Free and Total testosterone checkup, here are the numbers below:

When I first looked at the results, I was a bit relieved.

I mean, it says “normal”, right?

If you look at the reference range in the lower right hand corners, you’ll see a range of 264 – 916 ng/dl for Total serum testosterone, and 8.7-25.1 pg/ml for Free (direct) testosterone.

I also created a chart which shows the normal ranges for men ages 25 – 60:

So, that’s technically normal.

But is it REALLY?

I decided to turn to an old blood test result I had done a bit shy of 4 years ago (I was 33 years old).

Unfortunately, at that time I didn’t have my total testosterone checked.

However, I DID have my Free Testosterone checked, which some say is actually the more important measure anyway.

Here were the results:

As you can see, the measurements done in the 2014 test were measured in ng/dl, and the latest measurements done just a couple weeks ago were measured in pg/ml.

Basically, this translates to the following:

March, 2014 – My free testosterone levels were 15.8 pg/ml.

November, 2017 – My free testosterone levels were 12.7 pg/ml.

That’s a 19.6% decrease in my FREE testosterone levels.

In just 4 short years.

This is WAY less than the 1 % reduction per year that is generally accepted as “normal”.

So, what went wrong?

My suspicion (and research) tells me, it’s the weed.

I know some of you pot heads are probably cursing at your screen or iphone right now, but hear me out…

What Do The Studies Have To Say?

If you search for Marijuana and testosterone studies, you’ll find a few of them.

I have a pretty good sense of how studies are conducted, and I’m well aware that many studies are a bit (ahem!) skewed in their findings.

Especially when it comes to a substance that’s been demonized as long as marijuana has.

For example, this study showed that long term exposure to marijuana has been described to affect the signals and functions of sexual organs, but even research results don’t always consistently agree on this point.

The study measured the effects of purified marijuana chemicals and marijuana condensate (ie smoke that turned into liquid) on many laboratory tests, and female rats.

It was found that the negative effects on the female sexual organs was related to other chemicals in the smoke liquid, not the purified chemicals as previously thought.

In this study regarding thc and testosterone, endocrine effects of marijuana in the male were analyzed.

It can be briefly summarized like this:  The body’s daily functions are ruled by the brain, through signals called hormones.

Marijuana affects several hormones’ signals from the brain, likely caused by the active ingredient in marijuana, referred to as THC.

This chemical negatively affects the function of normal hormones, including the cross-talk between the different parts of the brain.

Two of the important hormones responsible for the male’s sexual function, and the related signals from before and after were found to be lowered by THC. Research using THC on small animals have shown that male sexual organs are smaller, less active and less fertile, ie the sperms are less healthy as well.

These negative effects can be reversed with time. Other brain signals for growth, food breakdown and energy conversion, and blood pressure control were likely to be affected as well.

It should be noted that this is considered an old review, and there should have been more pre-clinical studies since.

In yet another study, the response to long-term use of marijuana in young men under 30 was measured through blood chemicals, especially those related to sexual function, the responsible signal testosterone and sperm counts.

The more marijuana use, the lower the testosterone and sperm counts but the effects can be reversed when use was stopped.

However, it was also noted that long-term use is likely to lead to irreversible change in the sexual organs.

Considering the age of this paper, study methods are still valid but the number of men looked at is too small for statistics. 

In this study, Four healthy men were randomly give cigarettes with and without marijuana chemical. After each smoking session blood tests, questionnaire, eyesight assessment and mind control of movement were negatively affected.

Considering the age of this study, and only 4 subjects, the statistic insignificance is pretty much meaningless.

Statistics are useful only when there are large number of subjects.

Otherwise, scientists tend to look for trends and direct effects.

Perhaps the most intriguing evidence was found in this study.  Cannabis extract was used on mice, and the result was smaller male sexual organs.   Even supplemental testosterone, or male hormone, given to the mice did not improve the developmental growth.

On the flip side, you have this study which measured the male hormone testosterone in blood from 27 young men during a 3-weeks period of marijuana use, smoking between 2-6 marijuana cigarettes a day. The results showed no changes during smoking or after.

But don’t think you’re out of the woods yet…

This is a very old paper, and the study consisted of only 27 subjects.

From a scientist’s point of view the whole study design is flawed to begin with. There are also many points that I’d criticize but 21-days cannot be considered as chronic in human (maybe for mice or rats).

Results from such old studies would be ignored in today’s science.

In a related study, measurements of sexual and stress hormones in both males and females of about 23-years of age found no difference in the levels, regardless of how often these men and women used marijuana.

This is also considered as old research, and doesn’t clarify how long these men and women have been using marijuana or only started using recently.

So, Does Any Of This Conclusively Prove That Marijuana Will Decrease Your Testosterone?

Not by a long shot.

However, in my anecdotal case, there seems to be some sort of an effect.

I’ve already purchased a home testosterone test kit which I’ll be using to check my testosterone levels in a few weeks, after I’ve had a chance to get all of the weed out of my system.

I plan on giving myself a full 30 days of abstaining from weed before I run the test.

In the meantime, click here to leave a comment below and be sure to click the “Notify me of follow up comments by email” box.

As soon as I get my test results back, I plan on posting an update here.

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Author: Rob Miller

Rob Miller founded SupplementCritique.com over 7 years ago, and has been the chief editor ever since. He has a diploma in Advanced Dietary Supplements Advisor, and worked at GNC for 3 years. He KNOWS supplements, both inside and out. Rob currently resides in Jupiter, FL, with his wife of 4 years.  Learn more about him in his Bio here. Follow him on Twitter , Facebook, LinkedIn, or find him on Google +. View all posts by Rob Miller