Prohormones and SARMs both grew out of the supplement world’s search for something stronger than protein powder but easier to get than steroids. They work in completely different ways. Prohormones are steroids in waiting; SARMs are a separate class of drug. Knowing the difference helps make sense of their risks.
- A prohormone is a precursor that the body converts into an active steroid hormone.
- Many prohormones were reclassified as controlled anabolic steroids after liver injuries and doping cases.
- SARMs are non-steroidal and act on the androgen receptor directly without conversion.
- Both categories have been plagued by mislabelled products and unapproved ingredients.
What a prohormone is
The body makes testosterone through a chain of steps, each converting one molecule into the next. A prohormone is a compound partway along that chain, or a synthetic cousin of one, that enzymes turn into an active hormone after it is swallowed. Androstenedione, made famous by baseball in the late 1990s, was the best-known example. Later products used more potent designer molecules that converted into strong oral steroids.
Why prohormones fell out of the supplement aisle
Because they were sold as supplements, early prohormones were not tested like drugs. Reports of liver injury, gynecomastia, cholesterol changes and positive doping tests accumulated. In the United States, laws in 2004 and 2014 added many prohormones to the list of controlled anabolic steroids. Many products that remained on the market were found to contain undeclared steroids. In Canada, health products need authorisation to be sold, and unauthorised products of this kind are not legal to sell as supplements.
How their risks arise
Conversion is unpredictable
How much of a prohormone becomes active hormone varies between people and with dose. Some convert partly into estrogen, causing gynecomastia; others into DHT-like compounds affecting hair and prostate.
Liver strain
Many designer prohormones were 17-alpha-methylated, the same modification that makes oral steroids hard on the liver. Several were linked to serious liver injury.
Suppression
Once converted, they suppress natural testosterone like any androgen.
How SARMs differ
SARMs are not hormones and do not need conversion. They bind the androgen receptor directly and were designed to favour muscle and bone over other tissues. That design avoids estrogen and DHT conversion, but SARMs still suppress natural testosterone and lower HDL, and none is approved. See how SARMs work for the detail.
| Prohormones | SARMs | |
|---|---|---|
| Chemical class | Steroid precursors | Non-steroidal |
| Needs conversion | Yes | No |
| Can become estrogen or DHT | Often | No |
| Liver injury reports | Many, especially methylated types | Several case reports |
| Suppresses natural testosterone | Yes | Yes |
| Approved as medicine | No | No |
Testing of products sold as prohormones and SARMs has repeatedly found different ingredients, undeclared steroids or none of the stated compound. Unknown ingredients mean unknown risks.
Why “legal steroid” marketing persists
Every few years a new compound is sold online as a legal alternative to steroids. The pattern repeats: a molecule with little human research is marketed with bodybuilder testimonials, regulators catch up after reports of harm, and the market moves on to the next one. The products change faster than the science. A useful rule is that anything strong enough to build muscle like a steroid is strong enough to carry steroid-like risks, whatever it is called.
Natural options with real evidence
Creatine monohydrate, adequate protein, progressive resistance training and enough sleep have far better evidence for building muscle than any prohormone or SARM, with a fraction of the risk. Our guide to building muscle naturally covers them.
The shared lesson
Both categories were marketed as halfway houses between supplements and steroids. In practice, they carry many of the same risks as steroids, sometimes with less information about what is in the product. Anyone considering any of these compounds should treat them with the same seriousness: baseline bloodwork, honest monitoring and a doctor who knows what you are taking.
Bloodwork worth discussing
Testosterone, LH and FSH, estradiol, a lipid panel, liver enzymes, a complete blood count and blood pressure. Our article on what to have in place before you start lists them in more detail.
Zionova and Genetix PharmaSARMsBrowse
Frequently asked questions
Are prohormones the same as steroids?
They become steroids once the body converts them, which is why many are now controlled as anabolic steroids.
Are SARMs safer than prohormones?
They avoid estrogen and DHT conversion, but they still suppress testosterone and lower HDL, and both suffer from unreliable products.
Can prohormones cause gynecomastia?
Yes, when they convert partly into estrogen.
Educational information only. Nothing here is medical advice or a recommendation to use any product. Anabolic steroids are Schedule IV under the Controlled Drugs and Substances Act. Talk to a doctor and get bloodwork before and after using any compound.
