Insulin-like Growth Factor 1 (IGF-1) is an anabolic molecule which appears to induce growth of the antlers themselves, although testosterone may be the primary growth factor. Currently, there is no evidence that serum IGF-1 is increased following Velvet Antler ingestion with one study using 1.5g of Velvet Antler for 11 weeks failing to increase serum IGF-1.
“I've been taking deer antler since 2012 so I've been taking it for years and I definitely believe in it. And for recovery after hard, intense workouts, deer antler is a must. Go to AntlerFarms.com, definitely get the [deer antler velvet extract tablets] and the [deer antler velvet capsules]. Take those two in combination and you will feel great.”*
Deer antler spray products are not cheap. Expect that buying a high-quality product will set you back about $60–$100 per bottle. When taken as directed, each bottle should last you about one month. You don’t need to refrigerate the spray. However, keep it away from very hot temperatures to preserve the chemical composition of the product. Manufacturers claim that you can start experiencing benefits within 3–4 days. However, results definitely differ from one person to the next.
It is recently gaining popularity in the USA as seen with the deer antler spray controversy a couple years ago concerning several professional athletes. Oh yeah, I heard its a performance enhancer. They were consuming it for its natural growth factors, extracted via cold water, which are known to promote growth and regeneration capacities. Natural? Yes, and healthy. Where does this stuff come from?
Mental Capacity and Alertness: If you’re tired of feeling like you’re experiencing life through a fog, Deer Antler Velvet can help fade the fog and give you the clarity of a good night’s sleep combined with a week’s vacation. You come at things sharp and focused. Instead of struggling to remember things words, decisions, insights and just your general alertness are sharpened.
Velvet antler in the form of deer antler spray has been at the center of multiple controversies with professional sports leagues and famous athletes allegedly using it for injury recovery and performance enhancement purposes. In mid-2011 a National Football League (NFL) player successfully sued a deer antler velvet spray manufacturer for testing positive for methyltestosterone in 2009 for a total amount of 5.4 million US dollars. In August 2011, Major League Baseball (MLB) added deer antler spray to their list of prohibited items because it contains "potentially contaminated nutritional supplements." 
A systemic review on human interventions makes note of a study conducted on patients of osteoarthritis (Edelman et al. 2000; cannot be located online) which found improvements in joint pain symptoms relative to baseline in the Velvet Antler group and not placebo, although a lack of information on blinding and randomization precludes results that can be drawn from this study.