I pulled this directly from Wikipedia:
USA
Ephedrine distribution is controlled by the government, and pharmacists may refuse to sell it to customers without a prescription.
In 1997, the FDA proposed a regulation on ephedra (the herb from which ephedrine is obtained), which limited an ephedra dose to 8 mg (of active ephedrine) with no more than 24 mg per day.[22] This proposed rule was withdrawn in part in 2000 because of "concerns regarding the agency's basis for proposing a certain dietary ingredient level and a duration of use limit for these products."[23] In 2004, the FDA created a ban on ephedrine alkaloids that are marketed for reasons other than asthma, colds, allergies, other disease, or traditional Asian use.[24] On April 14, 2005, the U.S. District Court for the District of Utah ruled that the FDA did not have proper evidence that low dosages of ephedrine alkaloids are actually unsafe,[2] but on August 17, 2006, the U.S. Court of Appeals for the Tenth Circuit in Denver upheld the FDA's final rule declaring all dietary supplements containing ephedrine alkaloids adulterated, and therefore illegal for marketing in the United States. [3] Furthermore, ephedrine is banned by NCAA, MLB, NFL, and PGA TOUR [25] Ephedrine is, however, still legal in many applications outside of dietary supplements. However, purchasing is currently limited and monitored, with specifics varying from state to state.
The House passed the Combat Methamphetamine Epidemic Act of 2005 as an amendment to the renewal of the USA PATRIOT Act. Signed into law by president George W. Bush on March 6, 2006, the act amended the US Code (21 USC 830) concerning the sale of ephedrine-containing products. The federal statute included the following requirements for merchants who sell these products:
A retrievable record of all purchases identifying the name and address of each party to be kept for two years
Required verification of proof of identity of all purchasers
Required protection and disclosure methods in the collection of personal information
Reports to the Attorney General of any suspicious payments or disappearances of the regulated products
Non-liquid dose form of regulated product may only be sold in unit dose blister packs
Regulated products are to be sold behind the counter or in a locked cabinet in such a way as to restrict access
Daily sales of regulated products not to exceed 3.6 grams without regard to the number of transactions
Monthly sales not to exceed 9 grams of pseudoephedrine base in regulated products
The law gives similar regulations to mail-order purchases, except the monthly sales limit is only 7.5 grams.
As a pure herb or tea, má huáng, containing ephedrine, is still sold legally in the USA. The law restricts/prohibits its being sold as a dietary supplement(pill) or as an ingredient/additive to other products, like diet pills.
Hope that helps clear it up for you.