Official Statement Regarding Casein, FEI & USEF Regulations, and StressLess®
It has come to our attention that misinformation is circulating regarding casein and its status on USEF and FEI prohibited substances lists. We believe it is important to clarify the facts so horse owners, riders, and industry professionals can make informed decisions.
Understanding USEF & FEI Substance Classifications
Both the USEF and FEI categorize prohibited substances into two distinct groups, and the distinction matters:
Banned Substances
These are substances considered to have no legitimate therapeutic use in equine medicine and/or a high potential for abuse. Examples include illegal drugs, certain human antidepressants, and powerful stimulants. These substances should never be present in a horse’s system.
Controlled Medications
These are therapeutic substances commonly used in veterinary care. While permitted in general use, they must be cleared from the horse’s system prior to competition.
Casein vs. Alpha-Casozepine
Casein is the primary protein found in bovine milk and dairy products. While horses are lactose intolerant and dairy is not a normal part of the equine diet, casein derivatives and extracts are used in some equine supplements.
Alpha-casozepine (sometimes referred to as “casozepine”) is a specific peptide derived from the hydrolysis of casein. Due to its anxiolytic (anti-anxiety) and calming effects, alpha-casozepine is classified by the FEI as a Controlled Medication, meaning it may be considered performance-affecting and should not be present at the time of competition.
Importantly, casein itself is not classified as a Banned Substance or Controlled Medication by the USEF or FEI, however, USEF rules broadly state that any substance that affects the central nervous system or alters behavior/performance is prohibited.
Inspire Equine made the proactive decision in 2019 to remove the term “show safe” from our packaging. This decision was made to properly align with evolving guidance from governing bodies, indicating that any calming product should not be used in competition settings.
StressLess® and Transparency
Casein has always been the active ingredient in StressLess®, and it has never been undisclosed or hidden under a proprietary ingredient name. Ingredient transparency has been a core value of Inspire Equine since the product’s inception. StressLess® is made in the US in an FDA-inspected cGMP facility, ensuring the product you are using meets strict quality, safety, and purity standards.
Product Availability Update
Beginning in 2026, StressLess® will no longer be distributed through Centerline Distribution. The product will remain available:
- On Amazon (with free shipping for Prime members)
- Directly through us at www.stresslesshorsesupplement.com/shop
Questions?
We encourage customers to always review competition rules applicable to their discipline and governing body. If you have questions or would like additional clarification, please contact us directly at info@stressless4horses.com.
We remain committed to accuracy, transparency, and equine well-being.
