Are Prohormones Safe to Use for Muscle Building?

Man with large muscles, seated, lifting a weight

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Performance-enhancing drugs (PEDs) are often used inside gym walls, during bodybuilding competitions, and by athletes on the field. A popular PED that can be purchased as a supplement is a prohormone, a chemical compound also known as an over-the-counter androgen. Manufacturers claim that prohormone supplements build muscle and burn fat. Like steroids, most prohormones are illegal in the US.

Many weightlifters, bodybuilders, and other athletes turn to steroids and hormone supplements like prohormone to enhance their athletic performance and/or muscle size. Some may be seeking a quick fix to increase muscle mass, while others could feel pressured to gain an edge over the competition.

What Are Prohormones?

In the body, prohormones are converted by an enzymatic process into anabolic hormones which help generate protein synthesis and stimulate muscle growth. These supplements can produce expeditious results, allowing bodybuilders to shift their body composition within a short time frame.

Bodybuilders can often build muscle and decrease body fat percentage much quicker when they use prohormones.

However, any gains or enhancements experienced from prohormone use are usually short-term and come with a price. Prohormone supplementation can accelerate testosterone levels, which leads to side effects similar to those of illegal anabolic steroids.

Legality of Prohormones

Some athletic associations, like the International Olympic Committee (IOC), have banned most, if not all, prohormone supplements. If you are a competing athlete and get drug tested, you should know what you can and cannot use. You should also be aware that some manufacturers add prohormone mixtures into supplements without disclosing them on the list of ingredients.

Keep in mind that the Food and Drug Administration (FDA) regulates dietary supplements with a different set of requirements than pharmaceutical drugs. Manufacturers are responsible for their own evaluation of the safety and labeling of their products before marketing, which explains why prohormone supplements are technically legal despite the health risks.

Prohormones Have a Checkered Past

When prohormones were first introduced in 1996, many athletes took advantage of their powerful abilities. For example, Major League Baseball legend Mark McGwire was known to take prohormones as he worked to break home run records. However, he soon became a central figure in a steroid scandal that shook the sports industry.

But nearly all prohormones on the market were banned when the Anabolic Steroid Control Act of 2004 was amended. The act stated that all prohormones for sale were considered illegal "controlled substances," and that using them was the same as taking androgenic-anabolic steroids (AAS).

Even still, prohormones didn't stay off the shelves for long. Manufacturers found ways to work around the 2004 law and started to sell them again in 2005. As these substances were discovered, they were added to the list of controlled substances. Prohormones are banned in the US, Canada, and Mexico, but since they are not illegal in many other countries, they may be smuggled into the US.

An anabolic steroid that slipped through the cracks when the 2004 law was amended was Dehydroepiandrosterone (DHEA). DHEA is technically legal in the US—in other countries, it's considered a controlled substance—and the Food and Drug Administration (FDA) permits it to be in dietary supplements. However, DHEA is prohibited in all sports by the World Anti-Doping Agency (WADA).

Although prohormones are now illegal, manufacturers try to add them to dietary supplements. They can still cause the same negative side effects as they did pre-2004.

Do Prohormones Actually Work?

A few clinical studies have investigated the effectiveness of prohormones. Here's what the research has to say.

Muscle Mass and Enhanced Performance

In a review of the effects of prohormone supplementation in humans published in the Canadian Journal of Applied Physiology, researchers found that prohormones might lead to anabolic and/or physical performance effects, but not enough to make taking them worth it.

The following side effects were observed:

  • Hormonal imbalances: Oral ingestion of greater or equal to 200 milligrams per day increased testosterone concentration and was also accompanied by increases in estrogen, which means that breasts can develop.
  • Decreased HDL cholesterol: Doses greater than 300 milligrams per day for as long as 12 weeks had no effect on body composition or physical performance and caused a decrease in high-density lipoprotein ("good") cholesterol.

The current evidence shows that over-the-counter oral prohormones are ineffective at increasing muscle mass and athletic performance. In addition, the risk-to-benefit ratio of usage is unfavorable, given the side effects.

Resistance Training

Research has examined the effects of serum testosterone and adaptations to resistance training in young adults using prohormones. An older study published in the Journal of the American Medical Association followed 30 healthy subjects aged 19 to 29 who were not taking any nutritional supplements or steroids and were not engaged in any resistance training.

The subjects were divided into two groups: 20 individuals performed eight weeks of whole-body resistance training and the remaining 10 were given a single 100-milligram prohormone dose. During weeks 1, 2, 4, 5, 7, and 8, the first group was randomly given either a 300-milligram dose of prohormone or a placebo.

Researchers measured subjects' testosterone changes, estrogen concentrations, muscle strength, muscle fiber, body composition, blood lipids, and liver activities. Results showed no significant increases in lean body mass or decreases in fat mass in both the prohormone and placebo groups. In the prohormone group, HDL cholesterol was reduced after two weeks and remained low.

Research suggests that prohormone supplementation during resistance training does not increase testosterone levels or boost muscle gain and may result in negative health consequences.

Medicinal Usage

A 2017 study published in the International Journal of Nephrology and Renovascular Disease examined whether medicinal use of vitamin D prohormones could treat patients with hyperparathyroidism, which is caused by a declining renal function in chronic kidney disease (CKD).

The researchers found that patients supplementing with prohormones during later stages of the disease received little benefit. Only the patients in early stages of the disease had some measurable level of success during their medical treatment with prohormone supplementation.

Supplementing medication with prohormones in some health conditions may benefit patients during particular phases of their treatment, and could be especially helpful for those with atrophied muscles or vitamin deficiencies.

Side Effects

Because prohormones are legal, many people assume they are safe for consumption. But it is important to understand that they do have the potential to cause substantial and damaging side effects.

These effects can vary based on the individual, as is the case with any dietary supplement. For some people, the effects can be severe and long-lasting, similar to the side effects of steroids.

The following side effects have been linked to prohormone use:

  • Headaches
  • Increased heart rate
  • Nausea
  • Stomach pain
  • Sleeplessness
  • Increased anxiety
  • Fatigue
  • Acne
  • Mood changes, which can range from slight moodiness to drastic swings in personality
  • Hair loss
  • Testicular shrinkage
  • Aggressive behavior
  • Increased or decreased libido
  • Enlarged female breast tissue (sometimes men will develop breasts)
  • Lack of motivation to do activities you used to do (similar to how you feel when you experience depression)

Long-lasting side effects of prohormone use can include cardiovascular risks, irreparable liver and kidney damage, and elevated cholesterol levels.

Who Should Avoid Using Prohormones?

Because of the side effects and the lack of sufficient evidence, over-the-counter prohormone supplements should be approached with caution. Anyone considering prohormones should consult with their healthcare provider before using them.

Prohormone use may be especially dangerous for the following groups:

  • People under 18 years of age
  • People who are breastfeeding
  • Those who are pregnant or actively trying to become pregnant
  • Individuals who want to lose weight

Should You Try Prohormones?

There is not enough research to make a distinguishable vote of confidence that you could benefit from supplementing your diet with prohormones. Peer-reviewed, placebo-controlled, randomized clinical trials should be conducted to demonstrate that oral prohormone supplementation can increase muscle mass. Until then, you should look to other, more substantive, scientifically backed ways to build more muscle.

The most effective way to stimulate muscle growth, according to the American Heart Association (AHA), is moderate- to high-intensity muscle-strengthening activities, such as lifting weights or using bodyweight training, for at least two days per week. You should also spend less time sitting and gradually increase the intensity of your exercise over time.

If decide to try prohormones, remember that they might not work. Not only would you waste your money, but you could experience negative side effects that can be detrimental to your health.

A Word From Verywell

Before beginning a muscle-building exercise routine, you might benefit from seeking the advice of a healthcare professional and a registered dietitian. This wellness team can help determine what is best for your body.

You should also consider any medications you may be taking and ask your doctor about potential drug interactions before taking prohormones. It's also possible that your medications may not be suitable for heavy workouts.

In addition, a healthcare professional can help you determine the right amount of protein and other nutrition you need so you can reach your body composition goals in a safe and effective manner.

12 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Jennifer Purdie, M.Ed, CPT
Jennifer Purdie, M.Ed, is a certified personal trainer, freelance writer, and author of "Growth Mindset for Athletes, Coaches and Trainers."