Yep, here is something from Blackenall:
"Will Paprika Test Positive? Paprika (a member of the pepper... More family) may naturally contain a low level of Capsaicin, a substance that is banned by USEF for use in competition. Please be advised, and use discretion, when using Blackenall (or any product containing Paprika) in competition horses. While we have never had a report of a positive test as the result of or Blackenall, or any commercially available product containing paprika, we want to be certain that you are informed of the fact that paprika can be a source of naturally occurring capsaicin. To put the capsaicin potency of paprika into relative terms consider that pure capsaicin has a rating of 16,000,000 Scoville Units (a unit of measurement of capsaicin level in peppers). Our paprika typically has a Scoville Unit score of less than 150--quite a significant difference. We know of some USEF competitors that will, simply as a precaution, remove products containing paprika from the diet approximately 7-10 days prior to competition. If you have questions with regard to the use of our Blackenall, please feel free to give HorseTech a call at 1-800-831-3309. Note for Competitive Riders: Some competitive riding associations prohibit specific ingredients. If you are showing, please check with your association for rules and regulations."
I know for a fact that Black as Knight has paprika so you have to be careful with it. I know other coat enhancers have it too (I think all the ones for dark horses do)