S.D. Codified Laws § 34-20D-1
No retailer may sell, in a single transaction, more than two packages containing pseudoephedrine or ephedrine as an active ingredient. For purposes of this chapter, the term, retailer, means any person who sells merchandise at retail and from whom original packages of nonprescription drugs are sold or taken to be sold at retail and who is licensed by the Board of Pharmacy to sell nonprescription drugs. This restriction does not apply to any sale made pursuant to a valid prescription drug order prescribed by a practitioner as defined in § 36-11-2 with appropriate authority. Any retailer or any employee of a retailer who sells packages containing pseudoephedrine or ephedrine in violation of this section is guilty of a Class 1 misdemeanor.
SDCL 34-20D-1