On March 31, 2016, FDA issued warning letters to seven companies over products containing methylsynephrine, which is also known as oxilofrine and p-hydroxyephedrine. The letters allege that methylsynephrine fails to meet the statutory definition of a dietary ingredient.  Section 321(ff)(1) defines a dietary ingredient as

  1. a vitamin;
  2. a mineral;
  3. an herb or other botanical;
  4. an amino acid;
  5. a dietary substance for use by man to supplement the diet by increasing the total dietary intake; or
  6. a concentrate, metabolite, constituent, extract, or combination of any ingredient described in clause (A), (B), (C), (D), or (E).

The letters did not discuss FDA’s perspective on the safety of the ingredient.  FDA officials have reported that the agency has received 47 adverse event reports associated with dietary supplements containing methylsynephrine.

In recent years, FDA has issued warning letters over other substances that the agency believes fail to meet standards for safety or dietary ingredient status.  Those substances include Acacia rigidula, BMPEA, DMAA, DMBA, Picamilon, and pure powdered caffeine.