Whenever I take predator I get a tingling feeling.. It's a strange feeling what it actually seems pretty cool. I read that this is a natural side effect of Beta Alanine. Predator works really well To give you increased strength and endurance. It's a really great product.. I pretty much like everything the beast sports makes. Their products are a little pricey but you pay for quality. I'd rather pay the extra money and get a top quality product than pay less and get something subpar.